Spring动态数据源实现读写分离详解

package com.bounter.mybatis.extension;

/**
 * 基于ThreadLocal实现的动态数据源容器，保证DynamicDataSource的线程安全性
 * @author simon
 *
 */
public class DynamicDataSourceHolder {

 private static final ThreadLocal<String> dataSourceHolder = new ThreadLocal<>();

 public static void setDataSource(String dataSourceKey) {
 dataSourceHolder.set(dataSourceKey);
 }

 public static String getDataSource() {
 return dataSourceHolder.get();
 }

 public static void clearDataSource() {
 dataSourceHolder.remove();
 }
}

package com.bounter.mybatis.extension;

import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;

/**
 * 自定义的Spring 动态数据源扩展类,用来实现Master、Slave数据源动态切换
 * @author simon
 *
 */
public class DynamicDataSource extends AbstractRoutingDataSource {

 @Override
 protected Object determineCurrentLookupKey() {
 //使用DynamicDataSourceHolder保证线程安全
 return DynamicDataSourceHolder.getDataSource();
 }

}

# Master DB
db.master.url=jdbc:mysql://192.168.168.110:3306/bounter?useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&allowMultiQueries=true&serverTimezone=PRC&useSSL=false
db.master.username=bounter
# AES encrypt,Base64 encode
db.master.password=ZNhnEjauk3pecZxxS84ofA==

# Slave DB
db.slave.url=jdbc:mysql://192.168.168.111:3306/database?useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&allowMultiQueries=true&serverTimezone=PRC&useSSL=false
db.slave.username=bounter
# AES encrypt,Base64 encode
db.slave.password=jFYmt2f57RHhzItYDhWiSA==

<!-- Master数据源 -->
<bean id="masterDataSource" class="com.alibaba.druid.pool.DruidDataSource"
 init-method="init" destroy-method="close">
 <!-- 基本属性 url、user、password -->
 <property name="url" value="${db.master.url}" />
 <property name="username" value="${db.master.username}" />
 <property name="password" value="${db.master.password}" />
 <!-- 配置初始化大小、最小、最大 -->
 <property name="initialSize" value="20" />
 <property name="minIdle" value="1" />
 <property name="maxActive" value="40" />
 <!-- 配置获取连接等待超时的时间 -->
 <property name="maxWait" value="60000" />
 <!-- 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒 -->
 <property name="timeBetweenEvictionRunsMillis" value="60000" />
 <!-- 配置一个连接在池中最小生存的时间，单位是毫秒 -->
 <property name="minEvictableIdleTimeMillis" value="300000" />
 <property name="validationQuery" value="SELECT 'x'" />
 <property name="testWhileIdle" value="true" />
 <property name="testOnBorrow" value="false" />
 <property name="testOnReturn" value="false" />
 <!-- 配置监控统计拦截的filters -->
 <property name="filters" value="stat" />
</bean>

<!-- Slave数据源 -->
<bean id="slaveDataSource" class="com.alibaba.druid.pool.DruidDataSource"
 init-method="init" destroy-method="close">
 <!-- 基本属性 url、user、password -->
 <property name="url" value="${db.slave.url}" />
 <property name="username" value="${db.slave.username}" />
 <property name="password" value="${db.slave.password}" />
 <!-- 配置初始化大小、最小、最大 -->
 <property name="initialSize" value="20" />
 <property name="minIdle" value="1" />
 <property name="maxActive" value="40" />
 <!-- 配置获取连接等待超时的时间 -->
 <property name="maxWait" value="60000" />
 <!-- 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒 -->
 <property name="timeBetweenEvictionRunsMillis" value="60000" />
 <!-- 配置一个连接在池中最小生存的时间，单位是毫秒 -->
 <property name="minEvictableIdleTimeMillis" value="300000" />
 <property name="validationQuery" value="SELECT 'x'" />
 <property name="testWhileIdle" value="true" />
 <property name="testOnBorrow" value="false" />
 <property name="testOnReturn" value="false" />
 <!-- 配置监控统计拦截的filters -->
 <property name="filters" value="stat" />
</bean>

<!-- 自定义动态数据源 -->
 <bean id="dataSource" class="com.bounter.mybatis.extension.DynamicDataSource">
 <property name="targetDataSources">
  <map key-type="java.lang.String">
  <!-- 配置读写数据源 -->
  <entry value-ref="masterDataSource" key="write"></entry>
  <entry value-ref="slaveDataSource" key="read"></entry>
  </map>
 </property>
 <property name="defaultTargetDataSource" ref="masterDataSource"></property>
 </bean>

package com.bounter.mybatis.aop;

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.springframework.context.annotation.EnableAspectJAutoProxy;
import org.springframework.stereotype.Component;

import com.bounter.mybatis.extension.DynamicDataSourceHolder;

/**
 * 数据源切面，通过dao方法前缀决定访问读、写数据源
 * @author simon
 *
 */
@Component
@Aspect
@EnableAspectJAutoProxy(proxyTargetClass = true)
public class DataSourceAspect {

 //读库数据源key
 private static final String DATASOURCE_KEY_READ = "read";
 //查询方法清单
 String[] queryMethods = {"find","get","query","count","select"};

 /**
 * dao层方法执行前选择数据源
 * @param point
 */
 @Before("execution(* com.bounter.mybatis.dao..*.*(..))")
 public void before(JoinPoint point) {
 // 获取到当前执行的方法名
 String methodName = point.getSignature().getName();
 //匹配查询方法
 for(String queryMethod : queryMethods) {
  if(methodName.startsWith(queryMethod)) {
  //查询方法设置数据源为读库
  DynamicDataSourceHolder.setDataSource(DATASOURCE_KEY_READ);
  break;
  }
 }
 }

 /**
 * dao层方法执行完后清空数据源选择
 * @param point
 */
 @After("execution(* com.bounter.mybatis.dao..*.*(..))")
 public void after(JoinPoint point) {
 DynamicDataSourceHolder.clearDataSource();
 }
}