[Spring]配置数据库读写分离

我们在上篇文章提到了Spring4+Hibernate4整合详解

下面我们开始配置数据库读写分离

第一步：首先在spring-hibernate.xml配置多个datasource,注意datasource的ID不同

    
    <bean name="masterDataSource" class="com.alibaba.druid.pool.DruidDataSource" 
            init-method="init" destroy-method="close">
        <property name="url" value="${jdbc_url}" />
        <property name="username" value="${jdbc_user}" />
        <property name="password" value="${jdbc_password}" />

        
        
        <property name="initialSize" value="0" />
        
        <property name="maxActive" value="20" />
        
        <property name="maxIdle" value="20" />
        
        <property name="minIdle" value="0" />
        
        <property name="maxWait" value="60000" />

        <property name="validationQuery" value="${validationQuery}" />
        <property name="testOnBorrow" value="false" />
        <property name="testOnReturn" value="false" />
        <property name="testWhileIdle" value="true" />

        
        <property name="timeBetweenEvictionRunsMillis" value="60000" />
        
        <property name="minEvictableIdleTimeMillis" value="25200000" />

        
        <property name="removeAbandoned" value="true" />
        
        <property name="removeAbandonedTimeout" value="1800" />
        
        <property name="logAbandoned" value="true" />

        
        
        

        
        <property name="filters" value="stat" />

    bean>


    
    <bean name="slaveDataSource" class="com.alibaba.druid.pool.DruidDataSource" 
            init-method="init" destroy-method="close">
        <property name="url" value="${jdbc_url1}" />
        <property name="username" value="${jdbc_user1}" />
        <property name="password" value="${jdbc_password1}" />

        
        
        <property name="initialSize" value="0" />
        
        <property name="maxActive" value="20" />
        
        <property name="maxIdle" value="20" />
        
        <property name="minIdle" value="0" />
        
        <property name="maxWait" value="60000" />

        <property name="validationQuery" value="${validationQuery}" />
        <property name="testOnBorrow" value="false" />
        <property name="testOnReturn" value="false" />
        <property name="testWhileIdle" value="true" />

        
        <property name="timeBetweenEvictionRunsMillis" value="60000" />
        
        <property name="minEvictableIdleTimeMillis" value="25200000" />

        
        <property name="removeAbandoned" value="true" />
        
        <property name="removeAbandonedTimeout" value="1800" />
        
        <property name="logAbandoned" value="true" />

        
        
        

        
        <property name="filters" value="stat" />

    bean>

第二步:写一个DynamicDataSource类继承AbstractRoutingDataSource，并实现determineCurrentLookupKey方法

public class DynamicDataSource extends AbstractRoutingDataSource{

    @Override
    protected Object determineCurrentLookupKey() {
        return DbContextHolder.getDbType();
    }
}

public class DbContextHolder {

    private static final ThreadLocal contextHolder = new ThreadLocal();

    @SuppressWarnings("unchecked")
    public static void setDbType(String dbType) {
        contextHolder.set(dbType);
    }

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

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

}

第三步:在spring-hibernate.xml配置动态数据源

    id="dataSource" class="test.jia.com.datasource.DynamicDataSource">
        <property name="targetDataSources">
            
        property>
        <property name="defaultTargetDataSource" ref="masterDataSource"/>
    

第四步:在spring-hibernate.xml配置sessionFactory(与上文一致即可)

第五步:在spring-hibernate.xml配置事务管理(与上文一致即可)

第六步:动态数据源的管理控制,可以采用AOP的控制方式

@Aspect
@Component
public class DynamicDataSourceAspect {


    /**
     * 注：Aspect不属于Spring开发的,需要导入相关Jar包
     *      
     *      aspectjrt.jar
     *      aspectjweaver-1.6.10.jar
     */

    @Pointcut("execution (* test.jia.com.service..*.*(..))")  
    public void serviceExecution(){}  

    @Before("serviceExecution()")  
    public void setDynamicDataSource(JoinPoint jp) {  

        String methodName = jp.getSignature().getName();

        if (methodName.contains("save")) {
            System.out.println("写入数据库,数据库名称：write_mysql");
            DbContextHolder.setDbType("slaveDataSource");
        }else if (methodName.contains("get")) {
            System.out.println("读取数据库,数据库名称:read_mysql");
            DbContextHolder.setDbType("masterDataSource");
        }

        for(Object o : jp.getArgs()) {  
            //处理具体的逻辑 ，根据具体的境况
            //DbContextHolder.setDbType("slaveDataSource");
        }  
    }  

}

在spring-hibernate.xml添加切面注解扫描

    
    <aop:aspectj-autoproxy/>

到此配置完毕,下面开始进行测试

    @RequestMapping("login")
    public String login(HttpServletRequest request , HttpServletResponse response){
        System.out.println("  welcome !  ");
        try {
            baseService.save(new LoginUser("李四"));

            /**
             * baseService.getObject()错误:
             * org.hibernate.HibernateException: 
             *  Could not obtain transaction-synchronized Session for current thread
             * 解决方案：
             *  Dao中之前使用的是
             *  sessionFactory.getCurrentSession()获取Session
             *  改为使用
             *  sessionFactory.openSession()获取Session
             *  
             *  但是getCurrentSession是受Spring管理的。
             *  openSession是不受Spring管理，需要手动开启事务，和释放session
             */
            baseService.getObject(LoginUser.class, 1);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "login";
    }

文章参考:http://www.cnblogs.com/xiaoblog/p/4720160.html