springboot+mybatis实现动态切换数据源

前几天有个需求，需要使用不同的数据源，例如某业务要用A数据源，另一个业务要用B数据源。我上网收集了一些资料整合了一下，虽然最后这个需求不了了之了，但是多数据源动态切换还是蛮好用的，所以记录一下，或许以后有用呢？或者自己感兴趣又想玩呢！

1.加个依赖

        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
　　　　　　　<version>1.3.1</version>
        </dependency>

2.application.properties配置文件

#主从数据库
master.db.driverClassName=com.mysql.jdbc.Driver
master.db.url=jdbc:mysql://localhost:3306/cbd?characterEncoding=UTF-8&useUnicode=true&useSSL=false
master.db.username=root
master.db.password=admin
slave.db.driverClassName=com.mysql.jdbc.Driver
slave.db.url=jdbc:mysql://localhost:3306/cbd_test?characterEncoding=UTF-8&useUnicode=true&useSSL=false
slave.db.username=root
slave.db.password=admin

mybatis.config-location= classpath:config/mybatis-config.xml
mybatis.mapper-locations=classpath:mapper/**/*.xml

3.禁用springboot默认加载数据源配置

@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})
public class Application {
    
    public static void main(String[] args) throws Exception {
        SpringApplication.run(Application.class, args);
    }
}

4.数据源配置类

/**
 * 主数据源
 */
@Configuration
@ConfigurationProperties(prefix = "master.db")
public class MasterDataSourceConfig {
    private String url;
    private String username;
    private String password;
    private String driverClassName;
}

/**
 * 从数据源配置
 */
@Configuration
@ConfigurationProperties(prefix = "slave.db")
public class SlaveDataSourceConfig {
    private String url;
    private String username;
    private String password;
    private String driverClassName;
}

/**
 * 数据源配置类
 */
@Configuration
public class DataSourceComponent {

    @Resource
    private MasterDataSourceConfig masterDataSourceConfig;

    @Resource
    private SlaveDataSourceConfig slaveDataSourceConfig;


     @Bean(name = "master")
    public DataSource masterDataSource() {
        DataSource dataSource = new DataSource();
        dataSource.setUrl(masterDataSourceConfig.getUrl());
        dataSource.setUsername(masterDataSourceConfig.getUsername());
        dataSource.setPassword(masterDataSourceConfig.getPassword());
        dataSource.setDriverClassName(masterDataSourceConfig.getDriverClassName());
        return dataSource;
    }

    @Bean(name = "slave")
    public DataSource slaveDataSource() {
        DataSource dataSource = new DataSource();
        dataSource.setUrl(slaveDataSourceConfig.getUrl());
        dataSource.setUsername(slaveDataSourceConfig.getUsername());
        dataSource.setPassword(slaveDataSourceConfig.getPassword());
        dataSource.setDriverClassName(slaveDataSourceConfig.getDriverClassName());
        return dataSource;
    }

    @Primary//不加这个会报错。
    @Bean(name = "multiDataSource")
    public MultiRouteDataSource exampleRouteDataSource() {
        MultiRouteDataSource multiDataSource = new MultiRouteDataSource();
        Map<Object, Object> targetDataSources = new HashMap<>();
        targetDataSources.put("master", masterDataSource());
        targetDataSources.put("slave", slaveDataSource());
        multiDataSource.setTargetDataSources(targetDataSources);
        multiDataSource.setDefaultTargetDataSource(masterDataSource());
        return multiDataSource;
    }
}

5.数据源上下文

/**
 * 数据源上下文
 */
public class DataSourceContext {
    private static final ThreadLocal<String> contextHolder = new ThreadLocal<>();

    public static void setDataSource(String value) {
        contextHolder.set(value);
    }

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

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

6.DataSource路由类

/*
*    重写的函数决定了最后选择的DataSource
*/
public class MultiRouteDataSource extends AbstractRoutingDataSource {

    @Override
    protected Object determineCurrentLookupKey() {
        //通过绑定线程的数据源上下文实现多数据源的动态切换,有兴趣的可以去查阅资料或源码
        return DataSourceContext.getDataSource();
    }

}

7.使用，修改上下文中的数据源就可以切换自己想要使用的数据源了。

    public UserVO findUser(String username) {
        DataSourceContext.setDataSource("slave");
        UserVO userVO = userMapper.findByVO(username);
        System.out.println(userVO.getName()+"=====================");
        return null;
    }

这种是在业务中使用代码设置数据源的方式，也可以使用AOP+注解的方式实现控制，方法多多！