带你了解mybatis如何实现读写分离

spring:
  datasource:
    master:
      jdbc-url: jdbc:Mysql://master域名:3306/test
      username: root
      passWord: 123456
      driver-class-name: com.mysql.jdbc.Driver
    slave1:
      jdbc-url: jdbc:mysql://slave域名:3306/test
      username: root   # 只读账户
      password: 123456
      driver-class-name: com.mysql.jdbc.Driver
    slave2:
      jdbc-url: jdbc:mysql://slave域名:3306/test
      username: root   # 只读账户
      password: 123456
      driver-class-name: com.mysql.jdbc.Driver

package com.cjs.example.enums;
public enum DBTypeEnum {
    MASTER, SLAVE1, SLAVE2;
}

public class DBContextHolder {
    private static  volatile ThreadLocal<DBTypeEnum> contextHolder = new ThreadLocal<>();
    public static synchronized void set(DBTypeEnum dbType) {
        contextHolder.set(dbType);
    }
    public static synchronized DBTypeEnum get() {
        return contextHolder.get();
    }
    public static void master() {
        set(DBTypeEnum.MASTER);
    }
    public static void slave() {
        set(DBTypeEnum.SLAVE1);
    }
    public static void slave2(){ set(DBTypeEnum.SLAVE2); }
    // 清除数据源名
    public static void clearDB() {
        contextHolder.remove();
    }
}

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

@Configuration
public class DataSourceConfig {
    @Bean
    @ConfigurationProperties("spring.datasource.master")
    public DataSource masterDataSource() {
        return DataSourceBuilder.create().build();
    }
    @Bean
    @ConfigurationProperties("spring.datasource.slave1")
    public DataSource slave1DataSource() {
        return DataSourceBuilder.create().build();
    }

    @Bean
    public DataSource myRoutingDataSource(@Qualifier("masterDataSource") DataSource masterDataSource,
                                          @Qualifier("slave1DataSource") DataSource slave1DataSource) {
        Map<Object, Object> targetDataSources = new HashMap<>();
        targetDataSources.put(DBTypeEnum.MASTER, masterDataSource);
        targetDataSources.put(DBTypeEnum.SLAVE1, slave1DataSource);
        MyRoutingDataSource myRoutingDataSource = new MyRoutingDataSource();
        myRoutingDataSource.setDefaultTargetDataSource(masterDataSource);
        myRoutingDataSource.setTargetDataSources(targetDataSources);
        return myRoutingDataSource;
    }
}

@EnableTransactionManagement
@Configuration
@Import({TableSegInterceptor.class})
public class MyBatisConfig {
    @Resource(name = "myRoutingDataSource")
    private DataSource myRoutingDataSource;
    @Autowired
    private MybatisConfigProperty mybatisConfigProperty;
    @Autowired
    private TableSegInterceptor tableSegInterceptor;
    @Bean
    public SqlSessionFactory sqlSessionFactory() throws Exception {
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(myRoutingDataSource);
        // SpringBoot项目集成mybatis打包为jar运行时setTypeAliasesPackage无效解决
        VFS.addImplClass(SpringBootVFS.class);
        sqlSessionFactoryBean.setMapperLocations(
                new PathMatchingResourcePatternResolver().getResources(mybatisConfigProperty.getMapperLocations()));
        sqlSessionFactoryBean.setTypeAliasesPackage(mybatisConfigProperty.getTypeAliasesPackage());
        sqlSessionFactoryBean.setConfigLocation(
                new PathMatchingResourcePatternResolver().getResource(mybatisConfigProperty.getConfigLocation()));
        sqlSessionFactoryBean.setPlugins(new Interceptor[]{tableSegInterceptor});
        return sqlSessionFactoryBean.getObject();
    }
    @Bean
    public PlatfORMTransactionManager platformTransactionManager() {
        return new DataSourceTransactionManager(myRoutingDataSource);
    }
}

@Aspect
@Component
public class DataSourceAop {
    @Pointcut("!@annotation(com.ask.student.interceptor.annotation.Master) " +
            "&& (execution(* com.ask.student.service..*.select*(..)) " +
            "|| execution(* com.ask.student.service..*.get*(..))" +
            "|| execution(* com.ask.student.service..*.find*(..))" +
            ")")
    public void readPointcut() {
    }
    @Pointcut("@annotation(com.ask.student.interceptor.annotation.Master) " +
            "|| execution(* com.ask.student.service..*.insert*(..)) " +
            "|| execution(* com.ask.student.service..*.clean*(..)) " +
            "|| execution(* com.ask.student.service..*.reset*(..)) " +
            "|| execution(* com.ask.student.service..*.add*(..)) " +
            "|| execution(* com.ask.student.service..*.update*(..)) " +
            "|| execution(* com.ask.student.service..*.edit*(..)) " +
            "|| execution(* com.ask.student.service..*.delete*(..)) " +
            "|| execution(* com.ask.student.service..*.remove*(..))")
    public void writePointcut() {
    }
    @Before("readPointcut()")
    public void read() {
        DBContextHolder.slave();
    }
    @Before("writePointcut()")
    public void write() {
        DBContextHolder.master();
    }
    @After("readPointcut()||writePointcut()")
    public void afterSwitchDS(){
        DBContextHolder.clearDB();
    }
}

  datasource:
    dynamic:
      primary: master  #设置默认的数据源或者数据源组,默认值即为master
      strict: false #设置严格模式,默认false不启动. 启动后在未匹配到指定数据源时候会抛出异常,不启动则使用默认数据源.
      datasource:
        master:
          url: jdbc:mysql://xxx:3306/db0?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&useSSL=false&zeroDateTimeBehavior=convertToNull&serverTimezone=Asia/Shanghai
          username: admin
          password: 123456
          driver-class-name: com.mysql.cj.jdbc.Driver
          type: com.zaxxer.hikari.HikariDataSource
          hikari:
            minimum-idle: 5
            maximum-pool-size: 15
            auto-commit: true
            idle-timeout: 30000
            pool-name: springHikariCP
            max-lifetime: 1800000
            connection-timeout: 30000
            connection-test-query: SELECT 1
        slave1:
          url: jdbc:mysql://xxx:3306/db2?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&useSSL=false&zeroDateTimeBehavior=convertToNull&serverTimezone=Asia/Shanghai
          username: admin
          password: 123456
          driver-class-name: com.mysql.cj.jdbc.Driver
          type: com.zaxxer.hikari.HikariDataSource
          hikari:
            minimum-idle: 5
            maximum-pool-size: 15
            auto-commit: true
            idle-timeout: 30000
            pool-name: springHikariCP
            max-lifetime: 1800000
            connection-timeout: 30000
            connection-test-query: SELECT 1
        slave2:
          url: jdbc:mysql://xxx:3306/db3?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&useSSL=false&zeroDateTimeBehavior=convertToNull&serverTimezone=Asia/Shanghai
          username: admin
          password: 123456
          driver-class-name: com.mysql.cj.jdbc.Driver
          type: com.zaxxer.hikari.HikariDataSource
          hikari:
            minimum-idle: 5
            maximum-pool-size: 15
            auto-commit: true
            idle-timeout: 30000
            pool-name: springHikariCP
            max-lifetime: 1800000
            connection-timeout: 30000
            connection-test-query: SELECT 1

    @Override
    @DS("master")
    public DestMedia getOneByCodeFromEpg(String code) {
        QueryWrapper queryWrapper = new QueryWrapper();
        queryWrapper.eq("code", code);
        return super.getOne(queryWrapper);
    }