MySQL分布式集群-3.SpringBoot，Mybatis，

1.概要

• 读写分离分为master、slave两台MySQL服务器
• 在appcation.yml配置多数据源
• 为多数据源配置读写路由
• 在AOP中根据方法名或者@Master、@Slave来选择连接不同的数据库

2.代码

• application.yml

datasource:
    matser:
      driver-class-name: com.mysql.jdbc.Driver
      url: jdbc:mysql://localhost:3306/spring_boot_mybatis?useUnicode=true&characterEncoding=utf8&useSSL=false
      username: root
      password: **********
    slave:
      driver-class-name: com.mysql.jdbc.Driver
      url: jdbc:mysql://localhost:3306/spring_boot_mybatis?useUnicode=true&characterEncoding=utf8&useSSL=false
      username: root
      password: **********

• DBTypeEnum.java

package com.ctgu.springstart.db;

public enum DBTypeEnum {

    MASTER, SLAVE;

}

• DBContextHolder.java

package com.ctgu.springstart.db;

import java.util.concurrent.atomic.AtomicInteger;

public class DBContextHolder {

    private static final ThreadLocal<DBTypeEnum> contextHolder = new ThreadLocal<>();

    private static final AtomicInteger counter = new AtomicInteger(-1);

    public static void set(DBTypeEnum dbType){
        contextHolder.set(dbType);
    }

    public static DBTypeEnum get() {
        return contextHolder.get();
    }

    public static void master() {
        set(DBTypeEnum.MASTER);
        System.out.println("切换到master");
    }

    public static void slave() {
//        轮询
//        int index = counter.getAndIncrement() % 2;
//        if (counter.get() > 9999) {
//            counter.set(-1);
//        }
//        if (index == 0) {
//            set(DBTypeEnum.SLAVE);
//            System.out.println("切换到slave1");
//        }else {
//            set(DBTypeEnum.SLAVE2);
//            System.out.println("切换到slave2");
//        }
        set(DBTypeEnum.SLAVE);
        System.out.println("切换到slave");
    }

}

• MyRoutingDataSource.java

package com.ctgu.springstart.db;

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

public class MyRoutingDataSource extends AbstractRoutingDataSource {
    @Nullable
    @Override
    protected Object determineCurrentLookupKey() {
        return DBContextHolder.get();
    }

}

• MyBatisConfig.java

package com.ctgu.springstart.config;

import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;

import javax.annotation.Resource;
import javax.sql.DataSource;

@EnableTransactionManagement
@Configuration
public class MyBatisConfig {

    @Resource(name = "myRoutingDataSource")
    private DataSource myRoutingDataSource;

    @Bean
    public SqlSessionFactory sqlSessionFactory() throws Exception {
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(myRoutingDataSource);
        sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:mapper/*.xml"));
        return sqlSessionFactoryBean.getObject();
    }

    @Bean
    public PlatformTransactionManager platformTransactionManager() {
        return new DataSourceTransactionManager(myRoutingDataSource);
    }
}

未完，这不是注解方式，有空会改进、改进