MyBatis热部署

代码

import java.io.IOException;
import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.Timer;
import java.util.TimerTask;

import org.apache.ibatis.builder.xml.XMLMapperBuilder;
import org.apache.ibatis.executor.ErrorContext;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.session.SqlSessionFactory;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.core.io.Resource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;
import org.springframework.stereotype.Repository;

/**
 * 定时扫描并动态加载mybatis的SQL配置文件,刷新sql mapper cache,可以在修改xml后不用重启tomcat也能生效
 *
 * 扫描参数:<br/>
 * 1.RELOAD_INTERVAL:扫描时间间隔=3s<br/>
 * 2.XML_RESOURCE_PATTERN:当前CLASSPATH下xml通配符<br/>
 * 3.SESSION_FACTORY_BEAN_NAME:数据源session factory名称<br/>
 * 备注:本类在开发环境下使用,正式发布后注释掉applicationContext.xml中id=MyBatisDynamicLoader的bean
 *
 * @author MF
 * @version 1.0
 */
@Repository("XMLMapperLoader")
public class XMLMapperLoader implements InitializingBean, ApplicationContextAware {
	// 扫描时间间隔
	private static final long RELOAD_INTERVAL = 3000;

	private final HashMap<String, String> mappers = new HashMap<String, String>();
	private volatile ConfigurableApplicationContext context = null;
	private volatile Scanner scanner = null;

	@Override
	public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
		this.context = (ConfigurableApplicationContext) applicationContext;
	}

	@Override
	public void afterPropertiesSet() throws Exception {
		try {
			scanner = new Scanner();
			new Timer(true).schedule(new TimerTask() {
				public void run() {
					try {
						if (scanner.isChanged()) {
							scanner.reloadXML();
						}
					} catch (Exception e) {
						e.printStackTrace();
					}
				}
			}, 5 * 1000, RELOAD_INTERVAL);
		} catch (Exception e1) {
			e1.printStackTrace();
		}
	}

	class Scanner {
		private static final String XML_RESOURCE_PATTERN =
				ResourcePatternResolver.CLASSPATH_URL_PREFIX + "mapper/*/*.xml";
		private static final String SESSION_FACTORY_BEAN_NAME = "sqlSessionFactory";

		private final ResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();

		public Scanner() throws IOException {
			Resource[] resources = findResource();
			if (resources != null) {
				for (Resource resource : resources) {
					String key = resource.getURI().toString();
					String value = getMd(resource);
					mappers.put(key, value);
				}
			}
		}

		public void reloadXML() throws Exception {
			// 如果是单数据源用这个
			// SqlSessionFactory factory = context.getBean(SqlSessionFactory.class);
			/* 这里指定数据源,多数据源环境使用 */
			System.out.println("========== Reload SQL Cache on [" + SESSION_FACTORY_BEAN_NAME + "] ==========");
			SqlSessionFactory factory = (SqlSessionFactory) context.getBean(SESSION_FACTORY_BEAN_NAME);
			Configuration configuration = factory.getConfiguration();
			removeConfig(configuration);
			for (Resource resource : findResource()) {
				System.out.println(resource.getFilename());
				try {
					XMLMapperBuilder xmlMapperBuilder = new XMLMapperBuilder(resource.getInputStream(), configuration,
							resource.toString(), configuration.getSqlFragments());
					xmlMapperBuilder.parse();
				} finally {
					ErrorContext.instance().reset();
				}
			}
			System.out.println("========== Reload end ==========");
		}

		private void removeConfig(Configuration configuration) throws Exception {
			Class<?> classConfig = configuration.getClass();
			clearMap(classConfig, configuration, "mappedStatements");
			clearMap(classConfig, configuration, "caches");
			clearMap(classConfig, configuration, "resultMaps");
			clearMap(classConfig, configuration, "parameterMaps");
			clearMap(classConfig, configuration, "keyGenerators");
			clearMap(classConfig, configuration, "sqlFragments");
			clearSet(classConfig, configuration, "loadedResources");
		}

		@SuppressWarnings("rawtypes")
		private void clearMap(Class<?> classConfig, Configuration configuration, String fieldName) throws Exception {
			Field field = classConfig.getDeclaredField(fieldName);
			field.setAccessible(true);
			((Map) field.get(configuration)).clear();
		}

		@SuppressWarnings("rawtypes")
		private void clearSet(Class<?> classConfig, Configuration configuration, String fieldName) throws Exception {
			Field field = classConfig.getDeclaredField(fieldName);
			field.setAccessible(true);
			((Set) field.get(configuration)).clear();
		}

		public boolean isChanged() throws IOException {
			boolean isChanged = false;
			for (Resource resource : findResource()) {
				String key = resource.getURI().toString();
				String value = getMd(resource);
				if (!value.equals(mappers.get(key))) {
					isChanged = true;
					mappers.put(key, value);
				}
			}
			return isChanged;
		}

		private Resource[] findResource() throws IOException {
			return resourcePatternResolver.getResources(XML_RESOURCE_PATTERN);
		}

		private String getMd(Resource resource) throws IOException {
			return new StringBuilder()
					.append(resource.contentLength())
					.append("-")
					.append(resource.lastModified())
					.toString();
		}
	}
}

Spring加载方式

加载方式：在Spring XML文件中加入：（发布生产时要注释掉，不启动）
<!-- MyBatis 热加载，修改无需重新部署web容器的bean -->
<bean id ="MyBatisDynamicLoader" class= "com.xxx.XMLMapperLoader"/>