Spring動態數據源實現讀寫分離

一、創建基於ThreadLocal的動態數據源容器，保證數據源的線程安全性

package com.bounter.mybatis.extension;

/**
 * 基於ThreadLocal實現的動態數據源容器，保證DynamicDataSource的線程安全性
 * @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();
   }
}

二、定義Spring動態數據源擴展類,用來實現Master、Slave數據源動態切換

package com.bounter.mybatis.extension;

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

/**
 * 自定義的Spring 動態數據源擴展類,用來實現Master、Slave數據源動態切換
 * @author simon
 *
 */
public class DynamicDataSource extends AbstractRoutingDataSource {

   @Override
   protected Object determineCurrentLookupKey() {
      //使用DynamicDataSourceHolder保證線程安全
      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==

2. Spring 配置文件配置Master、Slave連接池，動態數據源

<!-- Master數據源 -->
<bean id="masterDataSource" class="com.alibaba.druid.pool.DruidDataSource"
   init-method="init" destroy-method="close">
   <!-- 基本屬性 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" />
   <!-- 配置獲取連接等待超時的時間 -->
   <property name="maxWait" value="60000" />
   <!-- 配置間隔多久才進行一次檢測，檢測需要關閉的空閑連接，單位是毫秒 -->
   <property name="timeBetweenEvictionRunsMillis" value="60000" />
   <!-- 配置一個連接在池中最小生存的時間，單位是毫秒 -->
   <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" />
   <!-- 配置監控統計攔截的filters -->
   <property name="filters" value="stat" />
</bean>

<!-- Slave數據源 -->
<bean id="slaveDataSource" class="com.alibaba.druid.pool.DruidDataSource"
   init-method="init" destroy-method="close">
   <!-- 基本屬性 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" />
   <!-- 配置獲取連接等待超時的時間 -->
   <property name="maxWait" value="60000" />
   <!-- 配置間隔多久才進行一次檢測，檢測需要關閉的空閑連接，單位是毫秒 -->
   <property name="timeBetweenEvictionRunsMillis" value="60000" />
   <!-- 配置一個連接在池中最小生存的時間，單位是毫秒 -->
   <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" />
   <!-- 配置監控統計攔截的filters -->
   <property name="filters" value="stat" />
</bean>

<!-- 自定義動態數據源 -->
   <bean id="dataSource" class="com.bounter.mybatis.extension.DynamicDataSource">
       <property name="targetDataSources">
           <map key-type="java.lang.String">
               <!-- 配置讀寫數據源 -->
               <entry value-ref="masterDataSource" key="write"></entry>
               <entry value-ref="slaveDataSource" key="read"></entry>
           </map>
       </property>
       <property name="defaultTargetDataSource" ref="masterDataSource"></property>
   </bean>

四、創建數據源切麵，通過AOP實現根據Dao層方法首碼動態選取讀、寫數據源

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;

/**
 * 數據源切麵，通過dao方法首碼決定訪問讀、寫數據源
 * @author simon
 *
 */
@Component
@Aspect
@EnableAspectJAutoProxy(proxyTargetClass = true)
public class DataSourceAspect {

   //讀庫數據源key
   private static final String DATASOURCE_KEY_READ = "read";
   //查詢方法清單
   String[] queryMethods = {"find","get","query","count","select"};

   /**
    * dao層方法執行前選擇數據源
    * @param point
    */
   @Before("execution(* com.bounter.mybatis.dao..*.*(..))")
   public void before(JoinPoint point) {
      // 獲取到當前執行的方法名
        String methodName = point.getSignature().getName();
        //匹配查詢方法
        for(String queryMethod : queryMethods) {
           if(methodName.startsWith(queryMethod)) {
              //查詢方法設置數據源為讀庫
              DynamicDataSourceHolder.setDataSource(DATASOURCE_KEY_READ);
              break;
           }
        }
   }

   /**
    * dao層方法執行完後清空數據源選擇
    * @param point
    */
   @After("execution(* com.bounter.mybatis.dao..*.*(..))")
   public void after(JoinPoint point) {
      DynamicDataSourceHolder.clearDataSource();
   }
}

github源碼地址：https://github.com/13babybear/bounter-mybatis