在上一篇博客《mybatis源代码分析:深入了解mybatis延迟加载机制》讲诉了mybatis延迟加载的具体机制及实现原理。

可以看出,如果查询结果对象中有一个属性是需要延迟加载的,那整个结果对象就是一个代理对象,后面对这个对象的访问,都是通过代理对象去访问的,那是否有更好的方法呢?

答案是有的。

Student对象关联Teacher对象,需要对Teacher对象延迟加载。

一种方式就是mybatis当前的这种做法,对Student进行代理,当访问到getTeacher时就进行延迟加载,设置其teacher对象;

还有一种方式就是对teacher对象进行代理,当第一次加载之后,就将Student对象关联的teacher对象替换为真实的对象,而不再使用代理对象,这样后面对Student及Teacher的访问,就都是访问的实际对象,而不是代理对象了。

修改之后的代码:http://download.csdn.net/detail/u014569459/7372195

关键修改点说明:

1.修改org\apache\ibatis\executor\resultset\DefaultResultSetHandler.java类,注销掉里面生成代理对象的代码

  private Object createResultObject(ResultSetWrapper rsw, ResultMap resultMap, ResultLoaderMap lazyLoader, String columnPrefix) throws SQLException {
final List<Class<?>> constructorArgTypes = new ArrayList<Class<?>>();
final List<Object> constructorArgs = new ArrayList<Object>();
final Object resultObject = createResultObject(rsw, resultMap, constructorArgTypes, constructorArgs, columnPrefix);
//comment by jerry
// if (resultObject != null && !typeHandlerRegistry.hasTypeHandler(resultMap.getType())) {
// final List<ResultMapping> propertyMappings = resultMap.getPropertyResultMappings();
// for (ResultMapping propertyMapping : propertyMappings) {
// if (propertyMapping.getNestedQueryId() != null && propertyMapping.isLazy()) { // issue gcode #109 && issue #149
// return configuration.getProxyFactory().createProxy(resultObject, lazyLoader, configuration, objectFactory, constructorArgTypes, constructorArgs);
// }
// }
// }
return resultObject;
}

2.修改org\apache\ibatis\executor\loader\cglib\CglibProxyFactory.java类

1)在createProxy方法增加两个参数Object parentObj,String fieldNameInParent,用于访问父对象。

  public Object createProxy(Object parentObj,String fieldNameInParent,Object target, ResultLoaderMap lazyLoader, Configuration configuration, ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
return EnhancedResultObjectProxyImpl.createProxy(parentObj,fieldNameInParent,target, lazyLoader, configuration, objectFactory, constructorArgTypes, constructorArgs);
}

2)在EnhancedResultObjectProxyImpl类中,增加parentObj和属性,并修改默认构造函数。

    private Object parentObj;
private String fieldNameInParent; private EnhancedResultObjectProxyImpl(Object parentObj,String fieldNameInParent,Class<?> type, ResultLoaderMap lazyLoader, Configuration configuration, ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
this.type = type;
this.lazyLoader = lazyLoader;
this.aggressive = configuration.isAggressiveLazyLoading();
this.lazyLoadTriggerMethods = configuration.getLazyLoadTriggerMethods();
this.objectFactory = objectFactory;
this.constructorArgTypes = constructorArgTypes;
this.constructorArgs = constructorArgs;
this.parentObj = parentObj;
this.fieldNameInParent = fieldNameInParent;
}

3)修改intercept函数

        if(parentObj!=null)
{
Field field = parentObj.getClass().getDeclaredField(fieldNameInParent);
Object obj = field.get(parentObj);
return method.invoke(obj, args);
}
else
{
return methodProxy.invokeSuper(enhanced, args);
}

修改文件列表(共4个):

1.CglibProxyFactory.java

/*
* Copyright 2009-2013 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.ibatis.executor.loader.cglib; import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set; import net.sf.cglib.proxy.Callback;
import net.sf.cglib.proxy.Enhancer;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy; import org.apache.ibatis.executor.loader.AbstractEnhancedDeserializationProxy;
import org.apache.ibatis.executor.loader.AbstractSerialStateHolder;
import org.apache.ibatis.executor.loader.ProxyFactory;
import org.apache.ibatis.executor.loader.ResultLoaderMap;
import org.apache.ibatis.executor.loader.WriteReplaceInterface;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.logging.Log;
import org.apache.ibatis.logging.LogFactory;
import org.apache.ibatis.reflection.ExceptionUtil;
import org.apache.ibatis.reflection.factory.ObjectFactory;
import org.apache.ibatis.reflection.property.PropertyCopier;
import org.apache.ibatis.reflection.property.PropertyNamer;
import org.apache.ibatis.session.Configuration; /**
* @author Clinton Begin
*/
public class CglibProxyFactory implements ProxyFactory { private static final Log log = LogFactory.getLog(CglibProxyFactory.class);
private static final String FINALIZE_METHOD = "finalize";
private static final String WRITE_REPLACE_METHOD = "writeReplace"; public CglibProxyFactory() {
try {
Resources.classForName("net.sf.cglib.proxy.Enhancer");
} catch (Throwable e) {
throw new IllegalStateException("Cannot enable lazy loading because CGLIB is not available. Add CGLIB to your classpath.", e);
}
} public Object createProxy(Object parentObj,String fieldNameInParent,Object target, ResultLoaderMap lazyLoader, Configuration configuration, ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
return EnhancedResultObjectProxyImpl.createProxy(parentObj,fieldNameInParent,target, lazyLoader, configuration, objectFactory, constructorArgTypes, constructorArgs);
}
public Object createProxy(Object target, ResultLoaderMap lazyLoader, Configuration configuration, ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
return EnhancedResultObjectProxyImpl.createProxy(null,null,target, lazyLoader, configuration, objectFactory, constructorArgTypes, constructorArgs);
} public Object createDeserializationProxy(Object target, Map<String, ResultLoaderMap.LoadPair> unloadedProperties, ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
return EnhancedDeserializationProxyImpl.createProxy(null,null,target, unloadedProperties, objectFactory, constructorArgTypes, constructorArgs);
} public void setProperties(Properties properties) {
} private static Object crateProxy(Class<?> type, Callback callback, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
Enhancer enhancer = new Enhancer();
enhancer.setCallback(callback);
enhancer.setSuperclass(type);
try {
type.getDeclaredMethod(WRITE_REPLACE_METHOD);
// ObjectOutputStream will call writeReplace of objects returned by writeReplace
log.debug(WRITE_REPLACE_METHOD + " method was found on bean " + type + ", make sure it returns this");
} catch (NoSuchMethodException e) {
enhancer.setInterfaces(new Class[]{WriteReplaceInterface.class});
} catch (SecurityException e) {
// nothing to do here
}
Object enhanced = null;
if (constructorArgTypes.isEmpty()) {
enhanced = enhancer.create();
} else {
Class<?>[] typesArray = constructorArgTypes.toArray(new Class[constructorArgTypes.size()]);
Object[] valuesArray = constructorArgs.toArray(new Object[constructorArgs.size()]);
enhanced = enhancer.create(typesArray, valuesArray);
}
return enhanced;
} private static class EnhancedResultObjectProxyImpl implements MethodInterceptor { private Class<?> type;
private ResultLoaderMap lazyLoader;
private boolean aggressive;
private Set<String> lazyLoadTriggerMethods;
private ObjectFactory objectFactory;
private List<Class<?>> constructorArgTypes;
private List<Object> constructorArgs;
private Object parentObj;
private String fieldNameInParent; private EnhancedResultObjectProxyImpl(Object parentObj,String fieldNameInParent,Class<?> type, ResultLoaderMap lazyLoader, Configuration configuration, ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
this.type = type;
this.lazyLoader = lazyLoader;
this.aggressive = configuration.isAggressiveLazyLoading();
this.lazyLoadTriggerMethods = configuration.getLazyLoadTriggerMethods();
this.objectFactory = objectFactory;
this.constructorArgTypes = constructorArgTypes;
this.constructorArgs = constructorArgs;
this.parentObj = parentObj;
this.fieldNameInParent = fieldNameInParent;
} public static Object createProxy(Object parentObj,String fieldNameInParent,Object target, ResultLoaderMap lazyLoader, Configuration configuration, ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) { final Class<?> type = target.getClass();
EnhancedResultObjectProxyImpl callback = new EnhancedResultObjectProxyImpl(parentObj,fieldNameInParent,type, lazyLoader, configuration, objectFactory, constructorArgTypes, constructorArgs);
Object enhanced = crateProxy(type, callback, constructorArgTypes, constructorArgs);
PropertyCopier.copyBeanProperties(type, target, enhanced);
return enhanced;
} public Object intercept(Object enhanced, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {
final String methodName = method.getName();
try {
synchronized (lazyLoader) {
if (WRITE_REPLACE_METHOD.equals(methodName)) {
Object original = null;
if (constructorArgTypes.isEmpty()) {
original = objectFactory.create(type);
} else {
original = objectFactory.create(type, constructorArgTypes, constructorArgs);
}
PropertyCopier.copyBeanProperties(type, enhanced, original);
if (lazyLoader.size() > 0) {
return new CglibSerialStateHolder(original, lazyLoader.getProperties(), objectFactory, constructorArgTypes, constructorArgs);
} else {
return original;
}
} else {
if (lazyLoader.size() > 0 && !FINALIZE_METHOD.equals(methodName)) {
if (aggressive || lazyLoadTriggerMethods.contains(methodName)) {
lazyLoader.loadAll();
} else if (PropertyNamer.isProperty(methodName)) {
final String property = PropertyNamer.methodToProperty(methodName);
if (lazyLoader.hasLoader(property)) {
lazyLoader.load(property);
}
}
}
}
} if(parentObj!=null)
{
Field field = parentObj.getClass().getDeclaredField(fieldNameInParent);
Object obj = field.get(parentObj);
return method.invoke(obj, args);
}
else
{
return methodProxy.invokeSuper(enhanced, args);
}
} catch (Throwable t) {
throw ExceptionUtil.unwrapThrowable(t);
}
}
} private static class EnhancedDeserializationProxyImpl extends AbstractEnhancedDeserializationProxy implements MethodInterceptor { private EnhancedDeserializationProxyImpl(Object parentObj,String fieldNameInParent,Class<?> type, Map<String, ResultLoaderMap.LoadPair> unloadedProperties, ObjectFactory objectFactory,
List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
super(type, unloadedProperties, objectFactory, constructorArgTypes, constructorArgs);
} public static Object createProxy(Object parentObj,String fieldNameInParent,Object target, Map<String, ResultLoaderMap.LoadPair> unloadedProperties, ObjectFactory objectFactory,
List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
final Class<?> type = target.getClass();
EnhancedDeserializationProxyImpl callback = new EnhancedDeserializationProxyImpl(parentObj,fieldNameInParent,type, unloadedProperties, objectFactory, constructorArgTypes, constructorArgs);
Object enhanced = crateProxy(type, callback, constructorArgTypes, constructorArgs);
PropertyCopier.copyBeanProperties(type, target, enhanced);
return enhanced;
} @Override
public Object intercept(Object enhanced, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {
final Object o = super.invoke(enhanced, method, args);
return (o instanceof AbstractSerialStateHolder) ? o : methodProxy.invokeSuper(o, args);
} @Override
protected AbstractSerialStateHolder newSerialStateHolder(Object userBean, Map<String, ResultLoaderMap.LoadPair> unloadedProperties, ObjectFactory objectFactory,
List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
return new CglibSerialStateHolder(userBean, unloadedProperties, objectFactory, constructorArgTypes, constructorArgs);
}
}
}

2.JavassistProxyFactory.java

/*
* Copyright 2009-2012 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.ibatis.executor.loader.javassist; import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set; import javassist.util.proxy.MethodHandler;
import javassist.util.proxy.Proxy;
import javassist.util.proxy.ProxyFactory; import org.apache.ibatis.executor.ExecutorException;
import org.apache.ibatis.executor.loader.AbstractEnhancedDeserializationProxy;
import org.apache.ibatis.executor.loader.AbstractSerialStateHolder;
import org.apache.ibatis.executor.loader.ResultLoaderMap;
import org.apache.ibatis.executor.loader.WriteReplaceInterface;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.logging.Log;
import org.apache.ibatis.logging.LogFactory;
import org.apache.ibatis.reflection.ExceptionUtil;
import org.apache.ibatis.reflection.factory.ObjectFactory;
import org.apache.ibatis.reflection.property.PropertyCopier;
import org.apache.ibatis.reflection.property.PropertyNamer;
import org.apache.ibatis.session.Configuration; /**
* @author Eduardo Macarron
*/
public class JavassistProxyFactory implements org.apache.ibatis.executor.loader.ProxyFactory { private static final Log log = LogFactory.getLog(JavassistProxyFactory.class);
private static final String FINALIZE_METHOD = "finalize";
private static final String WRITE_REPLACE_METHOD = "writeReplace"; public JavassistProxyFactory() {
try {
Resources.classForName("javassist.util.proxy.ProxyFactory");
} catch (Throwable e) {
throw new IllegalStateException("Cannot enable lazy loading because Javassist is not available. Add Javassist to your classpath.", e);
}
} public Object createProxy(Object target, ResultLoaderMap lazyLoader, Configuration configuration, ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
return EnhancedResultObjectProxyImpl.createProxy(null,null,target, lazyLoader, configuration, objectFactory, constructorArgTypes, constructorArgs);
}
public Object createProxy(Object parentObj, String fieldNameInParent,Object target, ResultLoaderMap lazyLoader, Configuration configuration, ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
return EnhancedResultObjectProxyImpl.createProxy(parentObj,fieldNameInParent,target, lazyLoader, configuration, objectFactory, constructorArgTypes, constructorArgs);
} public Object createDeserializationProxy(Object target, Map<String, ResultLoaderMap.LoadPair> unloadedProperties, ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
return EnhancedDeserializationProxyImpl.createProxy(target, unloadedProperties, objectFactory, constructorArgTypes, constructorArgs);
} public void setProperties(Properties properties) {
} private static Object crateProxy(Class<?> type, MethodHandler callback, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) { ProxyFactory enhancer = new ProxyFactory();
enhancer.setSuperclass(type); try {
type.getDeclaredMethod(WRITE_REPLACE_METHOD);
// ObjectOutputStream will call writeReplace of objects returned by writeReplace
log.debug(WRITE_REPLACE_METHOD + " method was found on bean " + type + ", make sure it returns this");
} catch (NoSuchMethodException e) {
enhancer.setInterfaces(new Class[]{WriteReplaceInterface.class});
} catch (SecurityException e) {
// nothing to do here
} Object enhanced = null;
Class<?>[] typesArray = constructorArgTypes.toArray(new Class[constructorArgTypes.size()]);
Object[] valuesArray = constructorArgs.toArray(new Object[constructorArgs.size()]);
try {
enhanced = enhancer.create(typesArray, valuesArray);
} catch (Exception e) {
throw new ExecutorException("Error creating lazy proxy. Cause: " + e, e);
}
((Proxy) enhanced).setHandler(callback);
return enhanced;
} private static class EnhancedResultObjectProxyImpl implements MethodHandler { private Class<?> type;
private ResultLoaderMap lazyLoader;
private boolean aggressive;
private Set<String> lazyLoadTriggerMethods;
private ObjectFactory objectFactory;
private List<Class<?>> constructorArgTypes;
private List<Object> constructorArgs;
private Object parentObj;
private String fieldNameInParent; private EnhancedResultObjectProxyImpl(Object parentObj, String fieldNameInParent,Class<?> type, ResultLoaderMap lazyLoader, Configuration configuration, ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
this.type = type;
this.lazyLoader = lazyLoader;
this.aggressive = configuration.isAggressiveLazyLoading();
this.lazyLoadTriggerMethods = configuration.getLazyLoadTriggerMethods();
this.objectFactory = objectFactory;
this.constructorArgTypes = constructorArgTypes;
this.constructorArgs = constructorArgs;
this.parentObj = parentObj;
this.fieldNameInParent = fieldNameInParent;
} public static Object createProxy(Object parentObj, String fieldNameInParent,Object target, ResultLoaderMap lazyLoader, Configuration configuration, ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
final Class<?> type = target.getClass();
EnhancedResultObjectProxyImpl callback = new EnhancedResultObjectProxyImpl(parentObj, fieldNameInParent,type, lazyLoader, configuration, objectFactory, constructorArgTypes, constructorArgs);
Object enhanced = crateProxy(type, callback, constructorArgTypes, constructorArgs);
PropertyCopier.copyBeanProperties(type, target, enhanced);
return enhanced;
} public Object invoke(Object enhanced, Method method, Method methodProxy, Object[] args) throws Throwable {
final String methodName = method.getName();
try {
synchronized (lazyLoader) {
if (WRITE_REPLACE_METHOD.equals(methodName)) {
Object original = null;
if (constructorArgTypes.isEmpty()) {
original = objectFactory.create(type);
} else {
original = objectFactory.create(type, constructorArgTypes, constructorArgs);
}
PropertyCopier.copyBeanProperties(type, enhanced, original);
if (lazyLoader.size() > 0) {
return new JavassistSerialStateHolder(original, lazyLoader.getProperties(), objectFactory, constructorArgTypes, constructorArgs);
} else {
return original;
}
} else {
if (lazyLoader.size() > 0 && !FINALIZE_METHOD.equals(methodName)) {
if (aggressive || lazyLoadTriggerMethods.contains(methodName)) {
lazyLoader.loadAll();
} else if (PropertyNamer.isProperty(methodName)) {
final String property = PropertyNamer.methodToProperty(methodName);
if (lazyLoader.hasLoader(property)) {
lazyLoader.load(property);
}
}
}
}
}
if(parentObj!=null)
{
Field field = parentObj.getClass().getDeclaredField(fieldNameInParent);
Object obj = field.get(parentObj);
return method.invoke(obj, args);
}
else
{
return methodProxy.invoke(enhanced, args);
}
} catch (Throwable t) {
throw ExceptionUtil.unwrapThrowable(t);
}
}
} private static class EnhancedDeserializationProxyImpl extends AbstractEnhancedDeserializationProxy implements MethodHandler { private EnhancedDeserializationProxyImpl(Class<?> type, Map<String, ResultLoaderMap.LoadPair> unloadedProperties, ObjectFactory objectFactory,
List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
super(type, unloadedProperties, objectFactory, constructorArgTypes, constructorArgs);
} public static Object createProxy(Object target, Map<String, ResultLoaderMap.LoadPair> unloadedProperties, ObjectFactory objectFactory,
List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
final Class<?> type = target.getClass();
EnhancedDeserializationProxyImpl callback = new EnhancedDeserializationProxyImpl(type, unloadedProperties, objectFactory, constructorArgTypes, constructorArgs);
Object enhanced = crateProxy(type, callback, constructorArgTypes, constructorArgs);
PropertyCopier.copyBeanProperties(type, target, enhanced);
return enhanced;
} @Override
public Object invoke(Object enhanced, Method method, Method methodProxy, Object[] args) throws Throwable {
final Object o = super.invoke(enhanced, method, args);
return (o instanceof AbstractSerialStateHolder) ? o : methodProxy.invoke(o, args);
} @Override
protected AbstractSerialStateHolder newSerialStateHolder(Object userBean, Map<String, ResultLoaderMap.LoadPair> unloadedProperties, ObjectFactory objectFactory,
List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
return new JavassistSerialStateHolder(userBean, unloadedProperties, objectFactory, constructorArgTypes, constructorArgs);
}
} }

3.ProxyFactory.java

/*
* Copyright 2012 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.ibatis.executor.loader; import java.util.List;
import java.util.Properties; import org.apache.ibatis.reflection.factory.ObjectFactory;
import org.apache.ibatis.session.Configuration; /**
* @author Eduardo Macarron
*/
public interface ProxyFactory { void setProperties(Properties properties); Object createProxy(Object target, ResultLoaderMap lazyLoader, Configuration configuration, ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs);
Object createProxy(Object parentObj,String fieldNameInParent,Object target, ResultLoaderMap lazyLoader, Configuration configuration, ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs); }

4.DefaultResultSetHandler.java

/*
* Copyright 2009-2014 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.ibatis.executor.resultset; import java.sql.CallableStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Set; import org.apache.ibatis.cache.CacheKey;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.executor.ExecutorException;
import org.apache.ibatis.executor.loader.ResultLoader;
import org.apache.ibatis.executor.loader.ResultLoaderMap;
import org.apache.ibatis.executor.parameter.ParameterHandler;
import org.apache.ibatis.executor.result.DefaultResultContext;
import org.apache.ibatis.executor.result.DefaultResultHandler;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.Discriminator;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.ParameterMapping;
import org.apache.ibatis.mapping.ParameterMode;
import org.apache.ibatis.mapping.ResultMap;
import org.apache.ibatis.mapping.ResultMapping;
import org.apache.ibatis.reflection.MetaClass;
import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.reflection.factory.ObjectFactory;
import org.apache.ibatis.session.AutoMappingBehavior;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.session.ResultContext;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;
import org.apache.ibatis.type.TypeHandler;
import org.apache.ibatis.type.TypeHandlerRegistry; /**
* @author Clinton Begin
* @author Eduardo Macarron
*/
public class DefaultResultSetHandler implements ResultSetHandler { private static final Object NO_VALUE = new Object(); private final Executor executor;
private final Configuration configuration;
private final MappedStatement mappedStatement;
private final RowBounds rowBounds;
private final ParameterHandler parameterHandler;
private final ResultHandler resultHandler;
private final BoundSql boundSql;
private final TypeHandlerRegistry typeHandlerRegistry;
private final ObjectFactory objectFactory; // nested resultmaps
private final Map<CacheKey, Object> nestedResultObjects = new HashMap<CacheKey, Object>();
private final Map<CacheKey, Object> ancestorObjects = new HashMap<CacheKey, Object>();
private final Map<String, String> ancestorColumnPrefix = new HashMap<String, String>(); // multiple resultsets
private final Map<String, ResultMapping> nextResultMaps = new HashMap<String, ResultMapping>();
private final Map<CacheKey, PendingRelation> pendingRelations = new HashMap<CacheKey, PendingRelation>(); private static class PendingRelation {
public MetaObject metaObject;
public ResultMapping propertyMapping;
} public DefaultResultSetHandler(Executor executor, MappedStatement mappedStatement, ParameterHandler parameterHandler, ResultHandler resultHandler, BoundSql boundSql,
RowBounds rowBounds) {
this.executor = executor;
this.configuration = mappedStatement.getConfiguration();
this.mappedStatement = mappedStatement;
this.rowBounds = rowBounds;
this.parameterHandler = parameterHandler;
this.boundSql = boundSql;
this.typeHandlerRegistry = configuration.getTypeHandlerRegistry();
this.objectFactory = configuration.getObjectFactory();
this.resultHandler = resultHandler;
} //
// HANDLE OUTPUT PARAMETER
// public void handleOutputParameters(CallableStatement cs) throws SQLException {
final Object parameterObject = parameterHandler.getParameterObject();
final MetaObject metaParam = configuration.newMetaObject(parameterObject);
final List<ParameterMapping> parameterMappings = boundSql.getParameterMappings();
for (int i = 0; i < parameterMappings.size(); i++) {
final ParameterMapping parameterMapping = parameterMappings.get(i);
if (parameterMapping.getMode() == ParameterMode.OUT || parameterMapping.getMode() == ParameterMode.INOUT) {
if (ResultSet.class.equals(parameterMapping.getJavaType())) {
handleRefCursorOutputParameter((ResultSet) cs.getObject(i + 1), parameterMapping, metaParam);
} else {
final TypeHandler<?> typeHandler = parameterMapping.getTypeHandler();
metaParam.setValue(parameterMapping.getProperty(), typeHandler.getResult(cs, i + 1));
}
}
}
} private void handleRefCursorOutputParameter(ResultSet rs, ParameterMapping parameterMapping, MetaObject metaParam) throws SQLException {
try {
final String resultMapId = parameterMapping.getResultMapId();
final ResultMap resultMap = configuration.getResultMap(resultMapId);
final DefaultResultHandler resultHandler = new DefaultResultHandler(objectFactory);
final ResultSetWrapper rsw = new ResultSetWrapper(rs, configuration);
handleRowValues(rsw, resultMap, resultHandler, new RowBounds(), null);
metaParam.setValue(parameterMapping.getProperty(), resultHandler.getResultList());
} finally {
closeResultSet(rs); // issue #228 (close resultsets)
}
} //
// HANDLE RESULT SETS
// public List<Object> handleResultSets(Statement stmt) throws SQLException {
final List<Object> multipleResults = new ArrayList<Object>(); int resultSetCount = 0;
ResultSetWrapper rsw = getFirstResultSet(stmt); List<ResultMap> resultMaps = mappedStatement.getResultMaps();
int resultMapCount = resultMaps.size();
validateResultMapsCount(rsw, resultMapCount);
while (rsw != null && resultMapCount > resultSetCount) {
ResultMap resultMap = resultMaps.get(resultSetCount);
handleResultSet(rsw, resultMap, multipleResults, null);
rsw = getNextResultSet(stmt);
cleanUpAfterHandlingResultSet();
resultSetCount++;
} String[] resultSets = mappedStatement.getResulSets();
if (resultSets != null) {
while (rsw != null && resultSetCount < resultSets.length) {
ResultMapping parentMapping = nextResultMaps.get(resultSets[resultSetCount]);
if (parentMapping != null) {
String nestedResultMapId = parentMapping.getNestedResultMapId();
ResultMap resultMap = configuration.getResultMap(nestedResultMapId);
handleResultSet(rsw, resultMap, null, parentMapping);
}
rsw = getNextResultSet(stmt);
cleanUpAfterHandlingResultSet();
resultSetCount++;
}
} return collapseSingleResultList(multipleResults);
} private ResultSetWrapper getFirstResultSet(Statement stmt) throws SQLException {
ResultSet rs = stmt.getResultSet();
while (rs == null) {
// move forward to get the first resultset in case the driver
// doesn't return the resultset as the first result (HSQLDB 2.1)
if (stmt.getMoreResults()) {
rs = stmt.getResultSet();
} else {
if (stmt.getUpdateCount() == -1) {
// no more results. Must be no resultset
break;
}
}
}
return rs != null ? new ResultSetWrapper(rs, configuration) : null;
} private ResultSetWrapper getNextResultSet(Statement stmt) throws SQLException {
// Making this method tolerant of bad JDBC drivers
try {
if (stmt.getConnection().getMetaData().supportsMultipleResultSets()) {
// Crazy Standard JDBC way of determining if there are more results
if (!((!stmt.getMoreResults()) && (stmt.getUpdateCount() == -1))) {
ResultSet rs = stmt.getResultSet();
return rs != null ? new ResultSetWrapper(rs, configuration) : null;
}
}
} catch (Exception e) {
// Intentionally ignored.
}
return null;
} private void closeResultSet(ResultSet rs) {
try {
if (rs != null) {
rs.close();
}
} catch (SQLException e) {
// ignore
}
} private void cleanUpAfterHandlingResultSet() {
nestedResultObjects.clear();
ancestorColumnPrefix.clear();
} private void validateResultMapsCount(ResultSetWrapper rsw, int resultMapCount) {
if (rsw != null && resultMapCount < 1) {
throw new ExecutorException("A query was run and no Result Maps were found for the Mapped Statement '" + mappedStatement.getId()
+ "'. It's likely that neither a Result Type nor a Result Map was specified.");
}
} private void handleResultSet(ResultSetWrapper rsw, ResultMap resultMap, List<Object> multipleResults, ResultMapping parentMapping) throws SQLException {
try {
if (parentMapping != null) {
handleRowValues(rsw, resultMap, null, RowBounds.DEFAULT, parentMapping);
} else {
if (resultHandler == null) {
DefaultResultHandler defaultResultHandler = new DefaultResultHandler(objectFactory);
handleRowValues(rsw, resultMap, defaultResultHandler, rowBounds, null);
multipleResults.add(defaultResultHandler.getResultList());
} else {
handleRowValues(rsw, resultMap, resultHandler, rowBounds, null);
}
}
} finally {
closeResultSet(rsw.getResultSet()); // issue #228 (close resultsets)
}
} private List<Object> collapseSingleResultList(List<Object> multipleResults) {
if (multipleResults.size() == 1) {
@SuppressWarnings("unchecked")
List<Object> returned = (List<Object>) multipleResults.get(0);
return returned;
}
return multipleResults;
} //
// HANDLE ROWS FOR SIMPLE RESULTMAP
// private void handleRowValues(ResultSetWrapper rsw, ResultMap resultMap, ResultHandler resultHandler, RowBounds rowBounds, ResultMapping parentMapping) throws SQLException {
if (resultMap.hasNestedResultMaps()) {
ensureNoRowBounds();
checkResultHandler();
handleRowValuesForNestedResultMap(rsw, resultMap, resultHandler, rowBounds, parentMapping);
} else {
handleRowValuesForSimpleResultMap(rsw, resultMap, resultHandler, rowBounds, parentMapping);
}
} private void ensureNoRowBounds() {
if (configuration.isSafeRowBoundsEnabled() && rowBounds != null && (rowBounds.getLimit() < RowBounds.NO_ROW_LIMIT || rowBounds.getOffset() > RowBounds.NO_ROW_OFFSET)) {
throw new ExecutorException("Mapped Statements with nested result mappings cannot be safely constrained by RowBounds. "
+ "Use safeRowBoundsEnabled=false setting to bypass this check.");
}
} protected void checkResultHandler() {
if (resultHandler != null && configuration.isSafeResultHandlerEnabled() && !mappedStatement.isResultOrdered()) {
throw new ExecutorException("Mapped Statements with nested result mappings cannot be safely used with a custom ResultHandler. "
+ "Use safeResultHandlerEnabled=false setting to bypass this check "
+ "or ensure your statement returns ordered data and set resultOrdered=true on it.");
}
} private void handleRowValuesForSimpleResultMap(ResultSetWrapper rsw, ResultMap resultMap, ResultHandler resultHandler, RowBounds rowBounds, ResultMapping parentMapping)
throws SQLException {
DefaultResultContext resultContext = new DefaultResultContext();
skipRows(rsw.getResultSet(), rowBounds);
while (shouldProcessMoreRows(rsw.getResultSet(), resultContext, rowBounds)) {
ResultMap discriminatedResultMap = resolveDiscriminatedResultMap(rsw.getResultSet(), resultMap, null);
Object rowValue = getRowValue(rsw, discriminatedResultMap);
storeObject(resultHandler, resultContext, rowValue, parentMapping, rsw.getResultSet());
}
} private void storeObject(ResultHandler resultHandler, DefaultResultContext resultContext, Object rowValue, ResultMapping parentMapping, ResultSet rs) throws SQLException {
if (parentMapping != null) {
linkToParent(rs, parentMapping, rowValue);
} else {
callResultHandler(resultHandler, resultContext, rowValue);
}
} private void callResultHandler(ResultHandler resultHandler, DefaultResultContext resultContext, Object rowValue) {
resultContext.nextResultObject(rowValue);
resultHandler.handleResult(resultContext);
} private boolean shouldProcessMoreRows(ResultSet rs, ResultContext context, RowBounds rowBounds) throws SQLException {
return !context.isStopped() && rs.next() && context.getResultCount() < rowBounds.getLimit();
} private void skipRows(ResultSet rs, RowBounds rowBounds) throws SQLException {
if (rs.getType() != ResultSet.TYPE_FORWARD_ONLY) {
if (rowBounds.getOffset() != RowBounds.NO_ROW_OFFSET) {
rs.absolute(rowBounds.getOffset());
}
} else {
for (int i = 0; i < rowBounds.getOffset(); i++) {
rs.next();
}
}
} //
// GET VALUE FROM ROW FOR SIMPLE RESULT MAP
// private Object getRowValue(ResultSetWrapper rsw, ResultMap resultMap) throws SQLException {
final ResultLoaderMap lazyLoader = new ResultLoaderMap();
Object resultObject = createResultObject(rsw, resultMap, lazyLoader, null);
if (resultObject != null && !typeHandlerRegistry.hasTypeHandler(resultMap.getType())) {
final MetaObject metaObject = configuration.newMetaObject(resultObject);
boolean foundValues = resultMap.getConstructorResultMappings().size() > 0;
if (shouldApplyAutomaticMappings(resultMap, !AutoMappingBehavior.NONE.equals(configuration.getAutoMappingBehavior()))) {
foundValues = applyAutomaticMappings(rsw, resultMap, metaObject, null) || foundValues;
}
foundValues = applyPropertyMappings(resultObject,rsw, resultMap, metaObject, lazyLoader, null) || foundValues;
foundValues = lazyLoader.size() > 0 || foundValues;
resultObject = foundValues ? resultObject : null;
return resultObject;
}
return resultObject;
} private boolean shouldApplyAutomaticMappings(ResultMap resultMap, boolean def) {
return resultMap.getAutoMapping() != null ? resultMap.getAutoMapping() : def;
} //
// PROPERTY MAPPINGS
// private boolean applyPropertyMappings(Object resultObject,ResultSetWrapper rsw, ResultMap resultMap, MetaObject metaObject, ResultLoaderMap lazyLoader, String columnPrefix)
throws SQLException {
final List<String> mappedColumnNames = rsw.getMappedColumnNames(resultMap, columnPrefix);
boolean foundValues = false;
final List<ResultMapping> propertyMappings = resultMap.getPropertyResultMappings();
for (ResultMapping propertyMapping : propertyMappings) {
final String column = prependPrefix(propertyMapping.getColumn(), columnPrefix);
if (propertyMapping.isCompositeResult()
|| (column != null && mappedColumnNames.contains(column.toUpperCase(Locale.ENGLISH)))
|| propertyMapping.getResultSet() != null) {
Object value = getPropertyMappingValue(rsw.getResultSet(), metaObject, propertyMapping, lazyLoader, columnPrefix);
//added by jerry
if (propertyMapping.getNestedQueryId() != null && propertyMapping.isLazy()) {
value = new dao.domain.Teacher();
try {
value = propertyMapping.getJavaType().newInstance();
value = configuration.getProxyFactory().createProxy(resultObject,propertyMapping.getProperty(),value, lazyLoader, configuration, objectFactory, new ArrayList(), new ArrayList());
} catch (Exception e) {
e.printStackTrace();
}
} final String property = propertyMapping.getProperty(); // issue #541 make property optional
if (value != NO_VALUE && property != null && (value != null || configuration.isCallSettersOnNulls())) { // issue #377, call setter on nulls
if (value != null || !metaObject.getSetterType(property).isPrimitive()) {
metaObject.setValue(property, value);
}
foundValues = true;
}
}
} return foundValues;
} private Object getPropertyMappingValue(ResultSet rs, MetaObject metaResultObject, ResultMapping propertyMapping, ResultLoaderMap lazyLoader, String columnPrefix)
throws SQLException {
if (propertyMapping.getNestedQueryId() != null) {
return getNestedQueryMappingValue(rs, metaResultObject, propertyMapping, lazyLoader, columnPrefix);
} else if (propertyMapping.getResultSet() != null) {
addPendingChildRelation(rs, metaResultObject, propertyMapping);
return NO_VALUE;
} else if (propertyMapping.getNestedResultMapId() != null) {
// the user added a column attribute to a nested result map, ignore it
return NO_VALUE;
} else {
final TypeHandler<?> typeHandler = propertyMapping.getTypeHandler();
final String column = prependPrefix(propertyMapping.getColumn(), columnPrefix);
return typeHandler.getResult(rs, column);
}
} private boolean applyAutomaticMappings(ResultSetWrapper rsw, ResultMap resultMap, MetaObject metaObject, String columnPrefix) throws SQLException {
final List<String> unmappedColumnNames = rsw.getUnmappedColumnNames(resultMap, columnPrefix);
boolean foundValues = false;
for (String columnName : unmappedColumnNames) {
String propertyName = columnName;
if (columnPrefix != null && columnPrefix.length() > 0) {
// When columnPrefix is specified,
// ignore columns without the prefix.
if (columnName.toUpperCase(Locale.ENGLISH).startsWith(columnPrefix)) {
propertyName = columnName.substring(columnPrefix.length());
} else {
continue;
}
}
final String property = metaObject.findProperty(propertyName, configuration.isMapUnderscoreToCamelCase());
if (property != null && metaObject.hasSetter(property)) {
final Class<?> propertyType = metaObject.getSetterType(property);
if (typeHandlerRegistry.hasTypeHandler(propertyType)) {
final TypeHandler<?> typeHandler = rsw.getTypeHandler(propertyType, columnName);
final Object value = typeHandler.getResult(rsw.getResultSet(), columnName);
if (value != null || configuration.isCallSettersOnNulls()) { // issue #377, call setter on nulls
if (value != null || !propertyType.isPrimitive()) {
metaObject.setValue(property, value);
}
foundValues = true;
}
}
}
}
return foundValues;
} // MULTIPLE RESULT SETS private void linkToParent(ResultSet rs, ResultMapping parentMapping, Object rowValue) throws SQLException {
CacheKey parentKey = createKeyForMultipleResults(rs, parentMapping, parentMapping.getColumn(), parentMapping.getForeignColumn());
PendingRelation parent = pendingRelations.get(parentKey);
if (parent != null) {
final Object collectionProperty = instantiateCollectionPropertyIfAppropriate(parent.propertyMapping, parent.metaObject);
if (rowValue != null) {
if (collectionProperty != null) {
final MetaObject targetMetaObject = configuration.newMetaObject(collectionProperty);
targetMetaObject.add(rowValue);
} else {
parent.metaObject.setValue(parent.propertyMapping.getProperty(), rowValue);
}
}
}
} private Object instantiateCollectionPropertyIfAppropriate(ResultMapping resultMapping, MetaObject metaObject) {
final String propertyName = resultMapping.getProperty();
Object propertyValue = metaObject.getValue(propertyName);
if (propertyValue == null) {
Class<?> type = resultMapping.getJavaType();
if (type == null) {
type = metaObject.getSetterType(propertyName);
}
try {
if (objectFactory.isCollection(type)) {
propertyValue = objectFactory.create(type);
metaObject.setValue(propertyName, propertyValue);
return propertyValue;
}
} catch (Exception e) {
throw new ExecutorException("Error instantiating collection property for result '" + resultMapping.getProperty() + "'. Cause: " + e, e);
}
} else if (objectFactory.isCollection(propertyValue.getClass())) {
return propertyValue;
}
return null;
} private void addPendingChildRelation(ResultSet rs, MetaObject metaResultObject, ResultMapping parentMapping) throws SQLException {
CacheKey cacheKey = createKeyForMultipleResults(rs, parentMapping, parentMapping.getColumn(), parentMapping.getColumn());
PendingRelation deferLoad = new PendingRelation();
deferLoad.metaObject = metaResultObject;
deferLoad.propertyMapping = parentMapping;
pendingRelations.put(cacheKey, deferLoad);
ResultMapping previous = nextResultMaps.get(parentMapping.getResultSet());
if (previous == null) {
nextResultMaps.put(parentMapping.getResultSet(), parentMapping);
} else {
if (!previous.equals(parentMapping)) {
throw new ExecutorException("Two different properties are mapped to the same resultSet");
}
}
} private CacheKey createKeyForMultipleResults(ResultSet rs, ResultMapping resultMapping, String names, String columns) throws SQLException {
CacheKey cacheKey = new CacheKey();
cacheKey.update(resultMapping);
if (columns != null && names != null) {
String[] columnsArray = columns.split(",");
String[] namesArray = names.split(",");
for (int i = 0 ; i < columnsArray.length ; i++) {
Object value = rs.getString(columnsArray[i]);
if (value != null) {
cacheKey.update(namesArray[i]);
cacheKey.update(value);
}
}
}
return cacheKey;
} //
// INSTANTIATION & CONSTRUCTOR MAPPING
// private Object createResultObject(ResultSetWrapper rsw, ResultMap resultMap, ResultLoaderMap lazyLoader, String columnPrefix) throws SQLException {
final List<Class<?>> constructorArgTypes = new ArrayList<Class<?>>();
final List<Object> constructorArgs = new ArrayList<Object>();
final Object resultObject = createResultObject(rsw, resultMap, constructorArgTypes, constructorArgs, columnPrefix);
//comment by jerry
// if (resultObject != null && !typeHandlerRegistry.hasTypeHandler(resultMap.getType())) {
// final List<ResultMapping> propertyMappings = resultMap.getPropertyResultMappings();
// for (ResultMapping propertyMapping : propertyMappings) {
// if (propertyMapping.getNestedQueryId() != null && propertyMapping.isLazy()) { // issue gcode #109 && issue #149
// return configuration.getProxyFactory().createProxy(resultObject, lazyLoader, configuration, objectFactory, constructorArgTypes, constructorArgs);
// }
// }
// }
return resultObject;
} private Object createResultObject(ResultSetWrapper rsw, ResultMap resultMap, List<Class<?>> constructorArgTypes, List<Object> constructorArgs, String columnPrefix)
throws SQLException {
final Class<?> resultType = resultMap.getType();
final List<ResultMapping> constructorMappings = resultMap.getConstructorResultMappings();
if (typeHandlerRegistry.hasTypeHandler(resultType)) {
return createPrimitiveResultObject(rsw, resultMap, columnPrefix);
} else if (constructorMappings.size() > 0) {
return createParameterizedResultObject(rsw, resultType, constructorMappings, constructorArgTypes, constructorArgs, columnPrefix);
} else {
return objectFactory.create(resultType);
}
} private Object createParameterizedResultObject(ResultSetWrapper rsw, Class<?> resultType, List<ResultMapping> constructorMappings, List<Class<?>> constructorArgTypes,
List<Object> constructorArgs, String columnPrefix) throws SQLException {
boolean foundValues = false;
for (ResultMapping constructorMapping : constructorMappings) {
final Class<?> parameterType = constructorMapping.getJavaType();
final String column = constructorMapping.getColumn();
final Object value;
if (constructorMapping.getNestedQueryId() != null) {
value = getNestedQueryConstructorValue(rsw.getResultSet(), constructorMapping, columnPrefix);
} else if (constructorMapping.getNestedResultMapId() != null) {
final ResultMap resultMap = configuration.getResultMap(constructorMapping.getNestedResultMapId());
value = getRowValue(rsw, resultMap);
} else {
final TypeHandler<?> typeHandler = constructorMapping.getTypeHandler();
value = typeHandler.getResult(rsw.getResultSet(), prependPrefix(column, columnPrefix));
}
constructorArgTypes.add(parameterType);
constructorArgs.add(value);
foundValues = value != null || foundValues;
}
return foundValues ? objectFactory.create(resultType, constructorArgTypes, constructorArgs) : null;
} private Object createPrimitiveResultObject(ResultSetWrapper rsw, ResultMap resultMap, String columnPrefix) throws SQLException {
final Class<?> resultType = resultMap.getType();
final String columnName;
if (resultMap.getResultMappings().size() > 0) {
final List<ResultMapping> resultMappingList = resultMap.getResultMappings();
final ResultMapping mapping = resultMappingList.get(0);
columnName = prependPrefix(mapping.getColumn(), columnPrefix);
} else {
columnName = rsw.getColumnNames().get(0);
}
final TypeHandler<?> typeHandler = rsw.getTypeHandler(resultType, columnName);
return typeHandler.getResult(rsw.getResultSet(), columnName);
} //
// NESTED QUERY
// private Object getNestedQueryConstructorValue(ResultSet rs, ResultMapping constructorMapping, String columnPrefix) throws SQLException {
final String nestedQueryId = constructorMapping.getNestedQueryId();
final MappedStatement nestedQuery = configuration.getMappedStatement(nestedQueryId);
final Class<?> nestedQueryParameterType = nestedQuery.getParameterMap().getType();
final Object nestedQueryParameterObject = prepareParameterForNestedQuery(rs, constructorMapping, nestedQueryParameterType, columnPrefix);
Object value = null;
if (nestedQueryParameterObject != null) {
final BoundSql nestedBoundSql = nestedQuery.getBoundSql(nestedQueryParameterObject);
final CacheKey key = executor.createCacheKey(nestedQuery, nestedQueryParameterObject, RowBounds.DEFAULT, nestedBoundSql);
final Class<?> targetType = constructorMapping.getJavaType();
final ResultLoader resultLoader = new ResultLoader(configuration, executor, nestedQuery, nestedQueryParameterObject, targetType, key, nestedBoundSql);
value = resultLoader.loadResult();
}
return value;
} private Object getNestedQueryMappingValue(ResultSet rs, MetaObject metaResultObject, ResultMapping propertyMapping, ResultLoaderMap lazyLoader, String columnPrefix)
throws SQLException {
final String nestedQueryId = propertyMapping.getNestedQueryId();
final String property = propertyMapping.getProperty();
final MappedStatement nestedQuery = configuration.getMappedStatement(nestedQueryId);
final Class<?> nestedQueryParameterType = nestedQuery.getParameterMap().getType();
final Object nestedQueryParameterObject = prepareParameterForNestedQuery(rs, propertyMapping, nestedQueryParameterType, columnPrefix);
Object value = NO_VALUE;
if (nestedQueryParameterObject != null) {
final BoundSql nestedBoundSql = nestedQuery.getBoundSql(nestedQueryParameterObject);
final CacheKey key = executor.createCacheKey(nestedQuery, nestedQueryParameterObject, RowBounds.DEFAULT, nestedBoundSql);
final Class<?> targetType = propertyMapping.getJavaType();
if (executor.isCached(nestedQuery, key)) {
executor.deferLoad(nestedQuery, metaResultObject, property, key, targetType);
} else {
final ResultLoader resultLoader = new ResultLoader(configuration, executor, nestedQuery, nestedQueryParameterObject, targetType, key, nestedBoundSql);
if (propertyMapping.isLazy()) {
lazyLoader.addLoader(property, metaResultObject, resultLoader);
} else {
value = resultLoader.loadResult();
}
}
}
return value;
} private Object prepareParameterForNestedQuery(ResultSet rs, ResultMapping resultMapping, Class<?> parameterType, String columnPrefix) throws SQLException {
if (resultMapping.isCompositeResult()) {
return prepareCompositeKeyParameter(rs, resultMapping, parameterType, columnPrefix);
} else {
return prepareSimpleKeyParameter(rs, resultMapping, parameterType, columnPrefix);
}
} private Object prepareSimpleKeyParameter(ResultSet rs, ResultMapping resultMapping, Class<?> parameterType, String columnPrefix) throws SQLException {
final TypeHandler<?> typeHandler;
if (typeHandlerRegistry.hasTypeHandler(parameterType)) {
typeHandler = typeHandlerRegistry.getTypeHandler(parameterType);
} else {
typeHandler = typeHandlerRegistry.getUnknownTypeHandler();
}
return typeHandler.getResult(rs, prependPrefix(resultMapping.getColumn(), columnPrefix));
} private Object prepareCompositeKeyParameter(ResultSet rs, ResultMapping resultMapping, Class<?> parameterType, String columnPrefix) throws SQLException {
final Object parameterObject = instantiateParameterObject(parameterType);
final MetaObject metaObject = configuration.newMetaObject(parameterObject);
boolean foundValues = false;
for (ResultMapping innerResultMapping : resultMapping.getComposites()) {
final Class<?> propType = metaObject.getSetterType(innerResultMapping.getProperty());
final TypeHandler<?> typeHandler = typeHandlerRegistry.getTypeHandler(propType);
final Object propValue = typeHandler.getResult(rs, prependPrefix(innerResultMapping.getColumn(), columnPrefix));
if (propValue != null) { // issue #353 & #560 do not execute nested query if key is null
metaObject.setValue(innerResultMapping.getProperty(), propValue);
foundValues = true;
}
}
return foundValues ? parameterObject : null;
} private Object instantiateParameterObject(Class<?> parameterType) {
if (parameterType == null) {
return new HashMap<Object, Object>();
} else {
return objectFactory.create(parameterType);
}
} //
// DISCRIMINATOR
// public ResultMap resolveDiscriminatedResultMap(ResultSet rs, ResultMap resultMap, String columnPrefix) throws SQLException {
Set<String> pastDiscriminators = new HashSet<String>();
Discriminator discriminator = resultMap.getDiscriminator();
while (discriminator != null) {
final Object value = getDiscriminatorValue(rs, discriminator, columnPrefix);
final String discriminatedMapId = discriminator.getMapIdFor(String.valueOf(value));
if (configuration.hasResultMap(discriminatedMapId)) {
resultMap = configuration.getResultMap(discriminatedMapId);
Discriminator lastDiscriminator = discriminator;
discriminator = resultMap.getDiscriminator();
if (discriminator == lastDiscriminator || !pastDiscriminators.add(discriminatedMapId)) {
break;
}
} else {
break;
}
}
return resultMap;
} private Object getDiscriminatorValue(ResultSet rs, Discriminator discriminator, String columnPrefix) throws SQLException {
final ResultMapping resultMapping = discriminator.getResultMapping();
final TypeHandler<?> typeHandler = resultMapping.getTypeHandler();
return typeHandler.getResult(rs, prependPrefix(resultMapping.getColumn(), columnPrefix));
} private String prependPrefix(String columnName, String prefix) {
if (columnName == null || columnName.length() == 0 || prefix == null || prefix.length() == 0) {
return columnName;
}
return prefix + columnName;
} //
// HANDLE NESTED RESULT MAPS
// private void handleRowValuesForNestedResultMap(ResultSetWrapper rsw, ResultMap resultMap, ResultHandler resultHandler, RowBounds rowBounds, ResultMapping parentMapping) throws SQLException {
final DefaultResultContext resultContext = new DefaultResultContext();
skipRows(rsw.getResultSet(), rowBounds);
Object rowValue = null;
while (shouldProcessMoreRows(rsw.getResultSet(), resultContext, rowBounds)) {
final ResultMap discriminatedResultMap = resolveDiscriminatedResultMap(rsw.getResultSet(), resultMap, null);
final CacheKey rowKey = createRowKey(discriminatedResultMap, rsw, null);
Object partialObject = nestedResultObjects.get(rowKey);
if (mappedStatement.isResultOrdered()) { // issue #577 && #542
if (partialObject == null && rowValue != null) {
nestedResultObjects.clear();
storeObject(resultHandler, resultContext, rowValue, parentMapping, rsw.getResultSet());
}
rowValue = getRowValue(rsw, discriminatedResultMap, rowKey, rowKey, null, partialObject);
} else {
rowValue = getRowValue(rsw, discriminatedResultMap, rowKey, rowKey, null, partialObject);
if (partialObject == null) {
storeObject(resultHandler, resultContext, rowValue, parentMapping, rsw.getResultSet());
}
}
}
if (rowValue != null && mappedStatement.isResultOrdered()) {
storeObject(resultHandler, resultContext, rowValue, parentMapping, rsw.getResultSet());
}
} //
// GET VALUE FROM ROW FOR NESTED RESULT MAP
// private Object getRowValue(ResultSetWrapper rsw, ResultMap resultMap, CacheKey combinedKey, CacheKey absoluteKey, String columnPrefix, Object partialObject) throws SQLException {
final String resultMapId = resultMap.getId();
Object resultObject = partialObject;
if (resultObject != null) {
final MetaObject metaObject = configuration.newMetaObject(resultObject);
putAncestor(absoluteKey, resultObject, resultMapId, columnPrefix);
applyNestedResultMappings(rsw, resultMap, metaObject, columnPrefix, combinedKey, false);
ancestorObjects.remove(absoluteKey);
} else {
final ResultLoaderMap lazyLoader = new ResultLoaderMap();
resultObject = createResultObject(rsw, resultMap, lazyLoader, columnPrefix);
if (resultObject != null && !typeHandlerRegistry.hasTypeHandler(resultMap.getType())) {
final MetaObject metaObject = configuration.newMetaObject(resultObject);
boolean foundValues = resultMap.getConstructorResultMappings().size() > 0;
if (shouldApplyAutomaticMappings(resultMap, AutoMappingBehavior.FULL.equals(configuration.getAutoMappingBehavior()))) {
foundValues = applyAutomaticMappings(rsw, resultMap, metaObject, columnPrefix) || foundValues;
}
foundValues = applyPropertyMappings(resultObject,rsw, resultMap, metaObject, lazyLoader, columnPrefix) || foundValues;
putAncestor(absoluteKey, resultObject, resultMapId, columnPrefix);
foundValues = applyNestedResultMappings(rsw, resultMap, metaObject, columnPrefix, combinedKey, true) || foundValues;
ancestorObjects.remove(absoluteKey);
foundValues = lazyLoader.size() > 0 || foundValues;
resultObject = foundValues ? resultObject : null;
}
if (combinedKey != CacheKey.NULL_CACHE_KEY) nestedResultObjects.put(combinedKey, resultObject);
}
return resultObject;
} private void putAncestor(CacheKey rowKey, Object resultObject, String resultMapId, String columnPrefix) {
if (!ancestorColumnPrefix.containsKey(resultMapId)) {
ancestorColumnPrefix.put(resultMapId, columnPrefix);
}
ancestorObjects.put(rowKey, resultObject);
} //
// NESTED RESULT MAP (JOIN MAPPING)
// private boolean applyNestedResultMappings(ResultSetWrapper rsw, ResultMap resultMap, MetaObject metaObject, String parentPrefix, CacheKey parentRowKey, boolean newObject) {
boolean foundValues = false;
for (ResultMapping resultMapping : resultMap.getPropertyResultMappings()) {
final String nestedResultMapId = resultMapping.getNestedResultMapId();
if (nestedResultMapId != null && resultMapping.getResultSet() == null) {
try {
final String columnPrefix = getColumnPrefix(parentPrefix, resultMapping);
final ResultMap nestedResultMap = getNestedResultMap(rsw.getResultSet(), nestedResultMapId, columnPrefix);
CacheKey rowKey = null;
Object ancestorObject = null;
if (ancestorColumnPrefix.containsKey(nestedResultMapId)) {
rowKey = createRowKey(nestedResultMap, rsw, ancestorColumnPrefix.get(nestedResultMapId));
ancestorObject = ancestorObjects.get(rowKey);
}
if (ancestorObject != null) {
if (newObject) metaObject.setValue(resultMapping.getProperty(), ancestorObject);
} else {
rowKey = createRowKey(nestedResultMap, rsw, columnPrefix);
final CacheKey combinedKey = combineKeys(rowKey, parentRowKey);
Object rowValue = nestedResultObjects.get(combinedKey);
boolean knownValue = (rowValue != null);
final Object collectionProperty = instantiateCollectionPropertyIfAppropriate(resultMapping, metaObject);
if (anyNotNullColumnHasValue(resultMapping, columnPrefix, rsw.getResultSet())) {
rowValue = getRowValue(rsw, nestedResultMap, combinedKey, rowKey, columnPrefix, rowValue);
if (rowValue != null && !knownValue) {
if (collectionProperty != null) {
final MetaObject targetMetaObject = configuration.newMetaObject(collectionProperty);
targetMetaObject.add(rowValue);
} else {
metaObject.setValue(resultMapping.getProperty(), rowValue);
}
foundValues = true;
}
}
}
} catch (SQLException e) {
throw new ExecutorException("Error getting nested result map values for '" + resultMapping.getProperty() + "'. Cause: " + e, e);
}
}
}
return foundValues;
} private String getColumnPrefix(String parentPrefix, ResultMapping resultMapping) {
final StringBuilder columnPrefixBuilder = new StringBuilder();
if (parentPrefix != null) columnPrefixBuilder.append(parentPrefix);
if (resultMapping.getColumnPrefix() != null) columnPrefixBuilder.append(resultMapping.getColumnPrefix());
final String columnPrefix = columnPrefixBuilder.length() == 0 ? null : columnPrefixBuilder.toString().toUpperCase(Locale.ENGLISH);
return columnPrefix;
} private boolean anyNotNullColumnHasValue(ResultMapping resultMapping, String columnPrefix, ResultSet rs) throws SQLException {
Set<String> notNullColumns = resultMapping.getNotNullColumns();
boolean anyNotNullColumnHasValue = true;
if (notNullColumns != null && !notNullColumns.isEmpty()) {
anyNotNullColumnHasValue = false;
for (String column: notNullColumns) {
rs.getObject(prependPrefix(column, columnPrefix));
if (!rs.wasNull()) {
anyNotNullColumnHasValue = true;
break;
}
}
}
return anyNotNullColumnHasValue;
} private ResultMap getNestedResultMap(ResultSet rs, String nestedResultMapId, String columnPrefix) throws SQLException {
ResultMap nestedResultMap = configuration.getResultMap(nestedResultMapId);
nestedResultMap = resolveDiscriminatedResultMap(rs, nestedResultMap, columnPrefix);
return nestedResultMap;
} //
// UNIQUE RESULT KEY
// private CacheKey createRowKey(ResultMap resultMap, ResultSetWrapper rsw, String columnPrefix) throws SQLException {
final CacheKey cacheKey = new CacheKey();
cacheKey.update(resultMap.getId());
List<ResultMapping> resultMappings = getResultMappingsForRowKey(resultMap);
if (resultMappings.size() == 0) {
if (Map.class.isAssignableFrom(resultMap.getType())) {
createRowKeyForMap(rsw, cacheKey);
} else {
createRowKeyForUnmappedProperties(resultMap, rsw, cacheKey, columnPrefix);
}
} else {
createRowKeyForMappedProperties(resultMap, rsw, cacheKey, resultMappings, columnPrefix);
}
return cacheKey;
} private CacheKey combineKeys(CacheKey rowKey, CacheKey parentRowKey) {
if (rowKey.getUpdateCount() > 1 && parentRowKey.getUpdateCount() > 1) {
CacheKey combinedKey;
try {
combinedKey = rowKey.clone();
} catch (CloneNotSupportedException e) {
throw new ExecutorException("Error cloning cache key. Cause: " + e, e);
}
combinedKey.update(parentRowKey);
return combinedKey;
}
return CacheKey.NULL_CACHE_KEY;
} private List<ResultMapping> getResultMappingsForRowKey(ResultMap resultMap) {
List<ResultMapping> resultMappings = resultMap.getIdResultMappings();
if (resultMappings.size() == 0) {
resultMappings = resultMap.getPropertyResultMappings();
}
return resultMappings;
} private void createRowKeyForMappedProperties(ResultMap resultMap, ResultSetWrapper rsw, CacheKey cacheKey, List<ResultMapping> resultMappings, String columnPrefix) throws SQLException {
for (ResultMapping resultMapping : resultMappings) {
if (resultMapping.getNestedResultMapId() != null && resultMapping.getResultSet() == null) { // Issue #392
final ResultMap nestedResultMap = configuration.getResultMap(resultMapping.getNestedResultMapId());
createRowKeyForMappedProperties(nestedResultMap, rsw, cacheKey, nestedResultMap.getConstructorResultMappings(),
prependPrefix(resultMapping.getColumnPrefix(), columnPrefix));
} else if (resultMapping.getNestedQueryId() == null) {
final String column = prependPrefix(resultMapping.getColumn(), columnPrefix);
final TypeHandler<?> th = resultMapping.getTypeHandler();
List<String> mappedColumnNames = rsw.getMappedColumnNames(resultMap, columnPrefix);
if (column != null && mappedColumnNames.contains(column.toUpperCase(Locale.ENGLISH))) { // Issue #114
final Object value = th.getResult(rsw.getResultSet(), column);
if (value != null) {
cacheKey.update(column);
cacheKey.update(value);
}
}
}
}
} private void createRowKeyForUnmappedProperties(ResultMap resultMap, ResultSetWrapper rsw, CacheKey cacheKey, String columnPrefix) throws SQLException {
final MetaClass metaType = MetaClass.forClass(resultMap.getType());
List<String> unmappedColumnNames = rsw.getUnmappedColumnNames(resultMap, columnPrefix);
for (String column : unmappedColumnNames) {
String property = column;
if (columnPrefix != null && columnPrefix.length() > 0) {
// When columnPrefix is specified,
// ignore columns without the prefix.
if (column.toUpperCase(Locale.ENGLISH).startsWith(columnPrefix)) {
property = column.substring(columnPrefix.length());
} else {
continue;
}
}
if (metaType.findProperty(property, configuration.isMapUnderscoreToCamelCase()) != null) {
String value = rsw.getResultSet().getString(column);
if (value != null) {
cacheKey.update(column);
cacheKey.update(value);
}
}
}
} private void createRowKeyForMap(ResultSetWrapper rsw, CacheKey cacheKey) throws SQLException {
List<String> columnNames = rsw.getColumnNames();
for (String columnName : columnNames) {
final String value = rsw.getResultSet().getString(columnName);
if (value != null) {
cacheKey.update(columnName);
cacheKey.update(value);
}
}
} }





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