springboot mybatis plus 多数据源

以下是使用Spring Boot和MyBatis Plus实现多数据源的最简解决方案：

1.在pom.xml文件中添加MyBatis Plus和Druid的依赖：

<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.4.3.1</version>
</dependency>
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid-spring-boot-starter</artifactId>
    <version>1.2.6</version>
</dependency>

2.在application.yml文件中配置数据源：

spring:
  datasource:
    master:
      url: jdbc:mysql://localhost:3306/db1?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=GMT%2B8
      username: root
      password: root
      driver-class-name: com.mysql.cj.jdbc.Driver
    slave:
      url: jdbc:mysql://localhost:3306/db2?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=GMT%2B8
      username: root
      password: root
      driver-class-name: com.mysql.cj.jdbc.Driver

3.创建数据源配置类：

@Configuration
@MapperScan(basePackages = "com.example.demo.mapper")
public class DataSourceConfig {

    @Bean
    @ConfigurationProperties(prefix = "spring.datasource.master")
    public DataSource masterDataSource() {
        return DruidDataSourceBuilder.create().build();
    }

    @Bean
    @ConfigurationProperties(prefix = "spring.datasource.slave")
    public DataSource slaveDataSource() {
        return DruidDataSourceBuilder.create().build();
    }

    @Bean
    public DynamicDataSource dynamicDataSource(@Qualifier("masterDataSource") DataSource masterDataSource,
                                               @Qualifier("slaveDataSource") DataSource slaveDataSource) {
        Map<Object, Object> targetDataSources = new HashMap<>();
        targetDataSources.put(DataSourceType.MASTER, masterDataSource);
        targetDataSources.put(DataSourceType.SLAVE, slaveDataSource);
        return new DynamicDataSource(masterDataSource, targetDataSources);
    }

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

    @Bean
    public SqlSessionTemplate sqlSessionTemplate(SqlSessionFactory sqlSessionFactory) {
        return new SqlSessionTemplate(sqlSessionFactory);
    }
}

4.创建数据源类型枚举类：

public enum DataSourceType {
    MASTER,
    SLAVE
}

5.创建动态数据源类：

public class DynamicDataSource extends AbstractRoutingDataSource {

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

    public DynamicDataSource(DataSource defaultTargetDataSource, Map<Object, Object> targetDataSources) {
        super.setDefaultTargetDataSource(defaultTargetDataSource);
        super.setTargetDataSources(targetDataSources);
        super.afterPropertiesSet();
    }

    @Override
    protected Object determineCurrentLookupKey() {
        return contextHolder.get();
    }

    public static void setDataSourceType(DataSourceType dataSourceType) {
        contextHolder.set(dataSourceType);
    }

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

6.创建数据源切换注解：

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD})
public @interface DataSource {
    DataSourceType value() default DataSourceType.MASTER;
}

7.创建数据源切换切面：

@Aspect
@Component
public class DataSourceAspect {

    @Pointcut("@annotation(com.example.demo.annotation.DataSource)")
    public void dataSourcePointCut() {
    }

    @Before("dataSourcePointCut()")
    public void before(JoinPoint joinPoint) {
        MethodSignature signature = (MethodSignature) joinPoint.getSignature();
        DataSource dataSource = signature.getMethod().getAnnotation(DataSource.class);
        if (dataSource != null) {
            DynamicDataSource.setDataSourceType(dataSource.value());
        }
    }

    @After("dataSourcePointCut()")
    public void after(JoinPoint joinPoint) {
        DynamicDataSource.clearDataSourceType();
    }
}

8.在Mapper接口中使用@DataSource注解指定数据源：

@DataSource(DataSourceType.MASTER)
List<User> selectAllUsers();

@DataSource(DataSourceType.SLAVE)
List<User> selectAllUsersFromSlave();

9.最后，启动Spring Boot应用程序并测试多数据源是否正常工作。

--相关问题--:
1. Spring Boot如何集成MyBatis Plus？
2. 如何在Spring Boot中配置