druid 多数据源_Springboot+mybatis(plus)+druid多数据源

在Spring Boot项目中使用MyBatis Plus和Druid多数据源的步骤如下：

1. 添加依赖

在`pom.xml`文件中添加以下依赖：

<!-- MyBatis Plus -->
<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.4.3.1</version>
</dependency>

<!-- Druid -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid-spring-boot-starter</artifactId>
    <version>1.2.6</version>
</dependency>

2. 配置Druid数据源

在`application.yml`中添加Druid数据源的配置：

spring:
  datasource:
    # 主数据源
    druid:
      url: jdbc:mysql://localhost:3306/main_db?useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8
      username: root
      password: root
      driver-class-name: com.mysql.cj.jdbc.Driver
      # Druid配置
      initialSize: 5
      minIdle: 5
      maxActive: 20
      testOnBorrow: false
      testOnReturn: false
      testWhileIdle: true
      timeBetweenEvictionRunsMillis: 60000
      validationQuery: SELECT 1 FROM DUAL
    # 从数据源
    druid2:
      url: jdbc:mysql://localhost:3306/sub_db?useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8
      username: root
      password: root
      driver-class-name: com.mysql.cj.jdbc.Driver
      # Druid配置
      initialSize: 5
      minIdle: 5
      maxActive: 20
      testOnBorrow: false
      testOnReturn: false
      testWhileIdle: true
      timeBetweenEvictionRunsMillis: 60000
      validationQuery: SELECT 1 FROM DUAL

3. 配置MyBatis Plus

在`application.yml`中添加MyBatis Plus的配置：

mybatis-plus:
  # 主数据源配置
  mapper-locations: classpath:mapper/main/*.xml
  type-aliases-package: com.example.main.entity
  global-config:
    db-config:
      id-type: auto
      field-strategy: not_empty
      logic-delete-value: 1
      logic-not-delete-value: 0
  configuration:
    map-underscore-to-camel-case: true
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  # 从数据源配置
  multi-datasource:
    main:
      mapper-locations: classpath:mapper/main/*.xml
      type-aliases-package: com.example.main.entity
    sub:
      mapper-locations: classpath:mapper/sub/*.xml
      type-aliases-package: com.example.sub.entity

4. 配置数据源路由

在`com.example.config`包下创建`DynamicDataSourceConfig`类，用于配置数据源路由：

@Configuration
public class DynamicDataSourceConfig {

    @Bean
    @ConfigurationProperties("spring.datasource.druid")
    public DataSource mainDataSource() {
        return DruidDataSourceBuilder.create().build();
    }

    @Bean
    @ConfigurationProperties("spring.datasource.druid2")
    public DataSource subDataSource() {
        return DruidDataSourceBuilder.create().build();
    }

    @Bean
    public DataSource dynamicDataSource() {
        DynamicDataSource dynamicDataSource = new DynamicDataSource();
        Map<Object, Object> dataSourceMap = new HashMap<>(2);
        dataSourceMap.put("main", mainDataSource());
        dataSourceMap.put("sub", subDataSource());
        // 将主数据源作为默认数据源
        dynamicDataSource.setDefaultTargetDataSource(mainDataSource());
        dynamicDataSource.setTargetDataSources(dataSourceMap);
        return dynamicDataSource;
    }

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

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

}

5. 配置数据源切换

在`com.example.config`包下创建`DynamicDataSource`类，用于实现数据源切换：

public class DynamicDataSource extends AbstractRoutingDataSource {

    @Override
    protected Object determineCurrentLookupKey() {
        return DataSourceContextHolder.getDataSource();
    }

}

在`com.example.config`包下创建`DataSourceContextHolder`类，用于存储当前数据源：

public class DataSourceContextHolder {

    private static final ThreadLocal<String> DATASOURCE_CONTEXT_HOLDER = new ThreadLocal<>();

    public static void setDataSource(String dataSource) {
        DATASOURCE_CONTEXT_HOLDER.set(dataSource);
    }

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

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

}

在`com.example.aop`包下创建`DataSourceAspect`类，用于切换数据源：

@Aspect
@Component
public class DataSourceAspect {

    @Pointcut("@annotation(com.example.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) {
            String value = dataSource.value();
            DataSourceContextHolder.setDataSource(value);
        }
    }

    @After("dataSourcePointCut()")
    public void after(JoinPoint joinPoint) {
        DataSourceContextHolder.clearDataSource();
    }

}

6. 使用多数据源

在需要使用从数据源的方法上加上`@DataSource("sub")`注解，如：

@Service
public class UserServiceImpl implements UserService {

    @Autowired
    private UserMapper userMapper;

    @Override
    public List<User> listUsers() {
        DataSourceContextHolder.setDataSource("sub");
        List<User> users = userMapper.selectList(null);
        DataSourceContextHolder.clearDataSource();
        return users;
    }

}

这样就完成了Spring Boot项目中使用MyBatis Plus和Druid多数据源的配置。