转 spring jpa 读写分离

pring jpa 读写分离

博客分类：

 
• spring

 

本文主要解决基于spring data jpa读写分离。

思想：在dataSource做路由，根据事务判断使用主从数据源。

背景：spring+spring data jpa（hibernate jpa）

首先是jpa配置，时间有限在原基础上该的，既有java配置也有xml配置，见谅。

先声明EntityManager

 

 

<!-- Jpa Entity Manager 配置 -->
    <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
                <property name="showSql" value="false" />
                <property name="generateDdl" value="true" />
                <property name="database" value="MYSQL" />
            </bean>
        </property>
        <property name="packagesToScan" value="com.lee"/>
        <property name="jpaProperties">
            <props>
                <!-- 命名规则 My_NAME->MyName -->
                <prop key="hibernate.ejb.naming_strategy">org.hibernate.cfg.ImprovedNamingStrategy</prop>
            </props>
        </property>
    </bean>

    <!-- 动态dataSource -->
    <bean id="dataSource" class="com.lee.spring.core.jpa.rws.RwDataSource">
        <property name="targetDataSources">
              <map key-type="java.lang.String">
                  <!-- write -->
                 <entry key="master" value-ref="masterDataSource"/>
                 <!-- read -->
                 <entry key="slave" value-ref="slaveDataSource"/>
              </map>
        </property>
        <property name="defaultTargetDataSource" ref="masterDataSource"/>
    </bean>

    <!-- 主（写）数据源 -->
    <bean id="masterDataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">
        <property name="driverClass" value="${jdbc.master.driver}" />
        <property name="jdbcUrl" value="${jdbc.master.url}" />
        <property name="user" value="${jdbc.master.username}" />
        <property name="password" value="${jdbc.master.password}" />
        <property name="maxPoolSize" value="30" />
        <property name="minPoolSize" value="10" />
        <property name="initialPoolSize" value="1" />
        <property name="maxIdleTime" value="0" />
        <property name="acquireIncrement" value="3" />
        <property name="acquireRetryAttempts" value="30" />
        <property name="checkoutTimeout" value="0" />
        <property name="idleConnectionTestPeriod" value="60" />
    </bean>

    <!-- 从（读）数据源 -->
    <bean id="slaveDataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">
        <property name="driverClass" value="${jdbc.slave.driver}" />
        <property name="jdbcUrl" value="${jdbc.slave.url}" />
        <property name="user" value="${jdbc.slave.username}" />
        <property name="password" value="${jdbc.slave.password}" />
        <property name="maxPoolSize" value="30" />
        <property name="minPoolSize" value="10" />
        <property name="initialPoolSize" value="1" />
        <property name="maxIdleTime" value="0" />
        <property name="acquireIncrement" value="3" />
        <property name="acquireRetryAttempts" value="30" />
        <property name="checkoutTimeout" value="0" />
        <property name="idleConnectionTestPeriod" value="60" />
    </bean>

 用java声明的jpa设置

 

 

import javax.annotation.Resource;
import javax.persistence.EntityManagerFactory;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.transaction.annotation.EnableTransactionManagement;

import com.lee.spring.core.jpa.rws.MyJpaTransactionManager;

/**
 * spring-jpa设置
 * @author lee
 *
 */
@Configuration
@PropertySource("classpath:/application.properties")
@EnableTransactionManagement
@EnableJpaRepositories(basePackages = {"com.lee.**.dao"})
public class SpringDaoConfig {
    private static final Logger logger = LoggerFactory.getLogger(SpringDaoConfig.class);
    @Resource(name="entityManagerFactory")
    private EntityManagerFactory entityManagerFactory;

    /**
     * 描述 : 负责解析资源文件
     * 这个类必须有，而且必须声明为static，否则不能正常解析
     * @return
     */
    @Bean
    public static PropertySourcesPlaceholderConfigurer placehodlerConfigurer() {
        logger.info("PropertySourcesPlaceholderConfigurer");
        return new PropertySourcesPlaceholderConfigurer();
    }

    @Bean(name="entityManagerFactory")
    public EntityManagerFactory entityManagerFactory() {
        return entityManagerFactory;
    }

    @Bean(name="transactionManager")
    public MyJpaTransactionManager transactionManager() {
        MyJpaTransactionManager transactionManager = new MyJpaTransactionManager();
        transactionManager.setEntityManagerFactory(entityManagerFactory);
        return transactionManager;
    }

}

 

 

由上可以看出跟平常不同的有两点

1. 自定义动态连接池RwDataSource
2. 自定义事务管理器MyJpaTransactionManager

其中MyJpaTransactionManager主要作用在于判断事务类别。因为我是使用注解@Transactional来声明事务，所以该类做了如下调整

 

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.transaction.TransactionDefinition;
import org.springframework.transaction.support.DefaultTransactionStatus;

@SuppressWarnings("serial")
public class MyJpaTransactionManager extends JpaTransactionManager{
    private static final Logger logger = LoggerFactory.getLogger(MyJpaTransactionManager.class);
    @Override
    protected void doBegin(Object transaction, TransactionDefinition definition) {
        if(definition.isReadOnly()){
            RwDataSourceHolder.localSlave();
        }else{
            RwDataSourceHolder.localMaster();
        }
        logger.info("jpa-transaction:begin-----now dataSource is ["+RwDataSourceHolder.getDataSouce()+"]");
        super.doBegin(transaction, definition);
    }
    @Override
    protected void doCommit(DefaultTransactionStatus status) {
        logger.info("jpa-transaction:commit-----now dataSource is ["+RwDataSourceHolder.getDataSouce()+"]");
        super.doCommit(status);
    }
}

 

 

上面涉及到definition.isReadOnly()来判断我的注解声明，依此来决定使用哪个dataSource。

public class RwDataSourceHolder {
    public static final String MASTER = "master";   //主(写)连接池
    public static final String SLAVE = "slave";     //从(读)连接池

    public static final ThreadLocal<String> holder = new ThreadLocal<String>();

    public static void localMaster() {
        holder.set(MASTER);
    }

    public static void localSlave() {
        holder.set(SLAVE);
    }

    public static String getDataSouce() {
        return holder.get();
    }
}

 最后是RwDataSource,这个完全基于spring提供的AbstractRoutingDataSource

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

public class RwDataSource extends AbstractRoutingDataSource {

    @Override
    protected Object determineCurrentLookupKey() {
        return RwDataSourceHolder.getDataSouce();
    }

}