基于mybatis+spring的读写分离

最新推荐文章于 2025-08-22 16:25:05 发布

xujieyang4j

最新推荐文章于 2025-08-22 16:25:05 发布

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分类专栏： mybatis 文章标签： spring mybatis

本文链接：https://blog.youkuaiyun.com/xujieyang4j/article/details/50816617

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本文介绍了一个针对MyBatis的自定义封装——RWSqlSessionTemplate，该类实现了根据不同的操作类型（如查询或更新）动态切换数据源（主从），但此方案不支持事务管理。

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在SqlSessionTemplate上层进行了封装，根据调用的方法，切换master/slave，但是无法支持事务

package com.xjy.study.spring.mybatis;

import java.util.List;
import java.util.concurrent.ThreadLocalRandom;

import javax.sql.DataSource;

import org.apache.ibatis.mapping.Environment;
import org.apache.ibatis.session.Configuration;
import org.mybatis.spring.SqlSessionTemplate;

// 不支持事务
public class RWSqlSessionTemplate {
    private SqlSessionTemplate sqlSessionTemplate;
    private DataSource masterDataSource;
    private List<DataSource> slaveDataSources;
    private volatile boolean isMaster = true;

    public void setSqlSessionTemplate(SqlSessionTemplate sqlSessionTemplate) {
        this.sqlSessionTemplate = sqlSessionTemplate;
    }

    public void setMasterDataSource(DataSource masterDataSource) {
        this.masterDataSource = masterDataSource;
    }

    public void setSlaveDataSources(List<DataSource> slaveDataSources) {
        this.slaveDataSources = slaveDataSources;
    }

    public <T> T selectOne(String statement, Object parameter) {
        switchToSlave();
        return sqlSessionTemplate.selectOne(statement, parameter);
    }

    public int update(String statement, Object parameter) {
        switchToMaster();
        return this.sqlSessionTemplate.update(statement, parameter);
      }

    private void switchToSlave() {
        if(isMaster) {
            switchToSlaveDataSource();
            isMaster = false;
        }
    }

    private void switchToMaster() {
        if(!isMaster) {
            switchToMasterDataSource();
            isMaster = true;
        }
    }

    private void switchToSlaveDataSource() {
        Configuration configuration = this.sqlSessionTemplate.getSqlSessionFactory().getConfiguration();
        Environment oldEnvironment = this.sqlSessionTemplate.getSqlSessionFactory().getConfiguration().getEnvironment();
        int index = ThreadLocalRandom.current().nextInt(slaveDataSources.size());
        Environment newEnvironment = new Environment(oldEnvironment.getId(), oldEnvironment.getTransactionFactory(), slaveDataSources.get(index));
        configuration.setEnvironment(newEnvironment);
    }

    private void switchToMasterDataSource() {
        Configuration configuration = this.sqlSessionTemplate.getSqlSessionFactory().getConfiguration();
        Environment oldEnvironment = this.sqlSessionTemplate.getSqlSessionFactory().getConfiguration().getEnvironment();
        Environment newEnvironment = new Environment(oldEnvironment.getId(), oldEnvironment.getTransactionFactory(), this.masterDataSource);
        configuration.setEnvironment(newEnvironment);
    }

}