SpringBoot（十一）-- 动态数据源

SpringBoot中使用动态数据源可以实现分布式中的分库技术，比如查询用户 就在用户库中查询，查询订单 就在订单库中查询。

一、配置文件application.properties

# 默认数据源
spring.datasource.url=jdbc:mysql://localhost:3306/consult
spring.datasource.username=myConsult
spring.datasource.password=123456
spring.datasource.driver-class-name=org.gjt.mm.mysql.Driver
# 更多数据源
custom.datasource.names=ds1,ds2
custom.datasource.ds1.driver-class-name=com.mysql.jdbc.Driver
custom.datasource.ds1.url=jdbc:mysql://localhost:3306/test1
custom.datasource.ds1.username=root
custom.datasource.ds1.password=123456
custom.datasource.ds2.driver-class-name=com.mysql.jdbc.Driver
custom.datasource.ds2.url=jdbc:mysql://localhost:3306/test2
custom.datasource.ds2.username=root
custom.datasource.ds2.password=123456

二、pox.xml

 <!-- aspectj -->
 <dependency>
     <groupId>org.aspectj</groupId>
     <artifactId>aspectjrt</artifactId>
 </dependency>
 <dependency>
     <groupId>org.aspectj</groupId>
     <artifactId>aspectjtools</artifactId>
 </dependency>
 <dependency>
      <groupId>org.aspectj</groupId>
      <artifactId>aspectjweaver</artifactId>
 </dependency>

三、使用aop自定义注解，实现动态切换数据源

1.动态数据源注册器

 package com.xsjt.dynamicDataSource;
 import java.util.HashMap;
 import java.util.Map;
 import javax.sql.DataSource;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.beans.MutablePropertyValues;
 import org.springframework.beans.PropertyValues;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
 import org.springframework.beans.factory.support.GenericBeanDefinition;
 import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
 import org.springframework.boot.bind.RelaxedDataBinder;
 import org.springframework.boot.bind.RelaxedPropertyResolver;
 import org.springframework.context.EnvironmentAware;
 import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.support.DefaultConversionService;
 import org.springframework.core.env.Environment;
 import org.springframework.core.type.AnnotationMetadata;
 /**
  * ClassName:DynamicDataSourceRegister
  * Date:     2017年11月13日 下午7:40:42
  * @author   Joe
  * @version
  * @since    JDK 1.8
  */
 public class DynamicDataSourceRegister implements ImportBeanDefinitionRegistrar, EnvironmentAware {
     private static final Logger logger = LoggerFactory.getLogger(DynamicDataSourceRegister.class);

     private ConversionService conversionService = new DefaultConversionService();
     private PropertyValues dataSourcePropertyValues;

     // 如配置文件中未指定数据源类型，使用该默认值
     private static final Object DATASOURCE_TYPE_DEFAULT = "org.apache.tomcat.jdbc.pool.DataSource";

 //     private static final Object DATASOURCE_TYPE_DEFAULT = "com.zaxxer.hikari.HikariDataSource";

     // 数据源
     private DataSource defaultDataSource;

     private Map<String, DataSource> customDataSources = new HashMap<String, DataSource>();

     public void registerBeanDefinitions( AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
         Map<Object, Object> targetDataSources = new HashMap<Object, Object>();
         // 将主数据源添加到更多数据源中
         targetDataSources.put("dataSource", defaultDataSource);
         DynamicDataSourceContextHolder.dataSourceIds.add("dataSource");
         // 添加更多数据源
         targetDataSources.putAll(customDataSources);
         for (String key : customDataSources.keySet()) {
             DynamicDataSourceContextHolder.dataSourceIds.add(key);
         }

         // 创建DynamicDataSource
         GenericBeanDefinition beanDefinition = new GenericBeanDefinition();
         beanDefinition.setBeanClass(DynamicDataSource.class);
         beanDefinition.setSynthetic(true);
         MutablePropertyValues mpv = beanDefinition.getPropertyValues();
         mpv.addPropertyValue("defaultTargetDataSource", defaultDataSource);
         mpv.addPropertyValue("targetDataSources", targetDataSources);
         registry.registerBeanDefinition("dataSource", beanDefinition); // 注册到Spring容器中

         logger.info("Dynamic DataSource Registry");
     }

     /**
      * 创建DataSource
      * @param type
      * @param driverClassName
      * @param url
      * @param username
      * @param password
      * @return
      */
     @SuppressWarnings("unchecked")
     public DataSource buildDataSource(Map<String, Object> dsMap) {
         try {
             Object type = dsMap.get("type");
             if (type == null)
                 type = DATASOURCE_TYPE_DEFAULT;// 默认DataSource

             Class<? extends DataSource> dataSourceType;
             dataSourceType = (Class<? extends DataSource>)Class.forName((String)type);

             String driverClassName = dsMap.get("driver-class-name").toString();
             String url = dsMap.get("url").toString();
             String username = dsMap.get("username").toString();
             String password = dsMap.get("password").toString();

             DataSourceBuilder factory = DataSourceBuilder.create()
                     .driverClassName(driverClassName)
                     .url(url)
                     .username(username)
                     .password(password)
                     .type(dataSourceType);
             return factory.build();
         }
         catch (ClassNotFoundException e) {
             e.printStackTrace();
         }
         return null;
     }

     /**
      * 加载多数据源配置
      */
     public void setEnvironment(Environment env) {
         initDefaultDataSource(env);
         initCustomDataSources(env);
     }

     /**
      * 初始化主数据源
      */
     private void initDefaultDataSource(Environment env) {
         // 读取主数据源
         RelaxedPropertyResolver propertyResolver = new RelaxedPropertyResolver(env, "spring.datasource.");
         Map<String, Object> dsMap = new HashMap<String, Object>();
         dsMap.put("type", propertyResolver.getProperty("type"));
         dsMap.put("driver-class-name",propertyResolver.getProperty("driver-class-name"));
         dsMap.put("url", propertyResolver.getProperty("url"));
         dsMap.put("username", propertyResolver.getProperty("username"));
         dsMap.put("password", propertyResolver.getProperty("password"));
         defaultDataSource = buildDataSource(dsMap);
         dataBinder(defaultDataSource, env);
     }

     /**
      * 为DataSource绑定更多数据
      * @param dataSource
      * @param env
      */
     private void dataBinder(DataSource dataSource, Environment env) {
         RelaxedDataBinder dataBinder = new RelaxedDataBinder(dataSource);
         //dataBinder.setValidator(new LocalValidatorFactory().run(this.applicationContext));
         dataBinder.setConversionService(conversionService);
         dataBinder.setIgnoreNestedProperties(false);//false
         dataBinder.setIgnoreInvalidFields(false);//false
         dataBinder.setIgnoreUnknownFields(true);//true
         if (dataSourcePropertyValues == null) {
             Map<String, Object> rpr = new RelaxedPropertyResolver(env, "spring.datasource").getSubProperties(".");
             Map<String, Object> values = new HashMap<String, Object>(rpr);
             // 排除已经设置的属性
             values.remove("type");
             values.remove("driver-class-name");
             values.remove("url");
             values.remove("username");
             values.remove("password");
             dataSourcePropertyValues = new MutablePropertyValues(values);
         }
         dataBinder.bind(dataSourcePropertyValues);
     }

     /**
      * 初始化更多数据源
      *
      */
     private void initCustomDataSources(Environment env) {
         // 读取配置文件获取更多数据源，也可以通过defaultDataSource读取数据库获取更多数据源
         RelaxedPropertyResolver propertyResolver = new RelaxedPropertyResolver( env, "custom.datasource.");
         String dsPrefixs = propertyResolver.getProperty("names");
         for (String dsPrefix : dsPrefixs.split(",")) {// 多个数据源
             Map<String, Object> dsMap = propertyResolver.getSubProperties(dsPrefix + ".");
             DataSource ds = buildDataSource(dsMap);
             customDataSources.put(dsPrefix, ds);
             dataBinder(ds, env);
         }
     }
 }

2.动态数据源适配器

package com.xsjt.dynamicDataSource;
import java.util.ArrayList;
import java.util.List;
/**
 * ClassName:DynamicDataSourceContextHolder
 * Date:     2017年11月13日 下午7:41:49
 * @author   Joe
 * @version
 * @since    JDK 1.8
 */
public class DynamicDataSourceContextHolder {
    private static final ThreadLocal<String> contextHolder = new ThreadLocal<String>();
    public static List<String> dataSourceIds = new ArrayList<String>();

    public static void setDataSourceType(String dataSourceType) {
        contextHolder.set(dataSourceType);
    }

    public static String getDataSourceType() {
        return contextHolder.get();
    }

    public static void clearDataSourceType() {
        contextHolder.remove();
    }

    /**
     * 判断指定DataSrouce当前是否存在
     *
     * @param dataSourceId
     * @return
     */
    public static boolean containsDataSource(String dataSourceId){
        return dataSourceIds.contains(dataSourceId);
    }
}

3.自定义注解

/**
 * ClassName:TargetDataSource
 * Date:     2017年11月13日 下午7:42:15
 * @author   Joe
 * @version
 * @since    JDK 1.8
 */
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface TargetDataSource {
    String name();
}

4.动态数据源切面

package com.xsjt.dynamicDataSource;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;
/**
 * ClassName:DynamicDataSourceAspect
 * Date:     2017年11月13日 下午7:44:09
 * @author   Joe
 * @version
 * @since    JDK 1.8
 */
@Aspect
//保证该AOP在@Transactional之前执行
@Order(-1)
@Component
public class DynamicDataSourceAspect {
    private static final Logger logger = LoggerFactory.getLogger(DynamicDataSourceAspect.class);

    /**
     * @Description 在方法执行之前执行  @annotation(ds) 会拦截有ds这个注解的方法即有 TargetDataSource这个注解的
     * @param @param point
     * @param @param ds
     * @param @throws Throwable 参数
     * @return void 返回类型
     * @throws
     */
    @Before("@annotation(ds)")
    public void changeDataSource(JoinPoint point, TargetDataSource ds)
            throws Throwable {
        String dsId = ds.name();
        if (!DynamicDataSourceContextHolder.containsDataSource(dsId)) {
            logger.error("数据源[{}]不存在，使用默认数据源 > {}", ds.name(), point.getSignature());
        }
        else {
            logger.debug("Use DataSource : {} > {}", ds.name(),point.getSignature());
            DynamicDataSourceContextHolder.setDataSourceType(ds.name());
        }
    }

    /**
     * @Description 在方法执行之后执行  @annotation(ds) 会拦截有ds这个注解的方法即有 TargetDataSource这个注解的
     * @param @param point
     * @param @param ds 参数
     * @return void 返回类型
     * @throws
     */
    @After("@annotation(ds)")
    public void restoreDataSource(JoinPoint point, TargetDataSource ds) {
        logger.debug("Revert DataSource : {} > {}", ds.name(), point.getSignature());
        DynamicDataSourceContextHolder.clearDataSourceType();
    }
}

5.继承Spring AbstractRoutingDataSource实现路由切换

package com.xsjt.dynamicDataSource;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
/**
 * ClassName:DynamicDataSource
 * 继承Spring AbstractRoutingDataSource实现路由切换
 * Date:     2017年11月13日 下午7:49:49
 * @author   Joe
 * @version
 * @since    JDK 1.8
 */
public class DynamicDataSource extends AbstractRoutingDataSource {

    @Override
    protected Object determineCurrentLookupKey() {
        return DynamicDataSourceContextHolder.getDataSourceType();
    }
}

四、怎么使用自定义的注解动态的切换数据源

只需要在service实现类中 对需要切换数据源的方法上 加上 自定义的注解即可，如：@TargetDataSource(name = "ds2")

五、启动类上添加@Import注解

　　//注册动态多数据源
　　@Import({DynamicDataSourceRegister.class})

六.源码下载

　　https://gitee.com/xbq168/spring-boot-learn