[Java知识库]springboot2+mybatis 注解方式2配置多数据源

?一、项目目录描述

java

- Application.java // 启动类

-config

? ? ? ? --各种配置文件

-mapper

? ? ? ? --master

? ? ? ? --slave

resources

-mapper

? ? ? ? --master

? ? ? ? --slave

二、相关依赖添加pom

?添加对应的依赖，因为要使用注解的方式，所以需要添加aop依赖。

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-aop</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.0.1</version>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <scope>runtime</scope>
</dependency>
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <optional>true</optional>
</dependency>

三、配置yml文件

0、配置yml文件?

spring:
  datasource:
    master:
      driver-class-name: com.mysql.jdbc.Driver
      jdbc-url: jdbc:mysql://localhost:3306/cache?useSSL=FALSE&serverTimezone=UTC
      username: root
      password: root
    slave:
      driver-class-name: com.mysql.jdbc.Driver
      jdbc-url: jdbc:mysql://localhost:3306/test?useSSL=FALSE&serverTimezone=UTC
      username: root
      password: root
# 这里不用配置mybatis的xml位置，在mybatis多数据源配置类中进行配置
#mybatis:
#  mapper-locations:
#    - classpath:mapper/db1/*.xml     
#    - classpath:mapper/db2/*.xml

?1、创建枚举类DataSourceType

public enum DataSourceType {
    master,
    slave
}

?2、动态数据源

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 getDataSource();
    }

    public static void setDataSource(DataSourceType dataSource) {
        contextHolder.set(dataSource);
    }

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

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

?3、Mybatis多数据源配置

@Configuration
@MapperScan(basePackages = "*********.mapper")
public class DynamicDataSourceConfig {

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


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

    @Bean
    public DynamicDataSource dataSource(@Qualifier("masterDataSource") DataSource masterDataSource,
                                        @Qualifier("slaveDataSource") DataSource slaveDataSource) {
        Map<Object, Object> map = new HashMap<>();
        map.put(DataSourceType.master, masterDataSource);
        map.put(DataSourceType.slave, slaveDataSource);
        DynamicDataSource dynamicDataSource = new DynamicDataSource();
        dynamicDataSource.setTargetDataSources(map);
        dynamicDataSource.setDefaultTargetDataSource(masterDataSource);
        return dynamicDataSource;
    }

    @Bean
    public SqlSessionFactory sqlSessionFactory(DynamicDataSource dynamicDataSource) throws Exception {
        SqlSessionFactoryBean factoryBean = new SqlSessionFactoryBean();
        factoryBean.setDataSource(dynamicDataSource);
        factoryBean.setMapperLocations(
                // 設置mybatisde xml所在的位置
                new PathMatchingResourcePatternResolver().getResources("classpath*:mapper/*/*.xml"));
        return factoryBean.getObject();
    }

    @Bean
    public PlatformTransactionManager transactionManager(DynamicDataSource dynamicDataSource) {
        return new DataSourceTransactionManager(dynamicDataSource);
    }
}

4、自定义注解

/**
 * @Description 自定义注解， 用于方法上
 * @Date 2022年10月18日 10:56:00
 */
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface DataSource {
    DataSourceType value() default DataSourceType.master;
}

?5、AOP切面设置数据源

@Order(-10) // 加上后会先切换数据源在切换事物
@Slf4j
@Aspect
@Component
public class DataSourceAspect {

    @Pointcut(value = "@annotation(******.config.DataSource)")
    public void logPointCut() {}

    @Around("logPointCut()")
    public Object beforeDataSource (ProceedingJoinPoint point) {
        MethodSignature methodSignature = (MethodSignature)point.getSignature();
        Method method = methodSignature.getMethod();
        DataSource dataSource;
        Object proceed;
        try {
            dataSource = method.getAnnotation(DataSource.class);
            if(dataSource == null) {
                DynamicDataSource.setDataSource(DataSourceType.master);
            } else  {
                DynamicDataSource.setDataSource(dataSource.value());
            }
            proceed = point.proceed();
            log.info("执行后的返回值： {}", proceed);
        } catch (Throwable throwable) {
            log.error("切换失败");
            proceed = throwable.toString();
        } finally {
            DynamicDataSource.clearDataSource();
        }
        return proceed;
    }
}

四、添加注解

在service层或者mapper层方法上添加注解即可

@Repository
public interface GroupMapper {
    @DataSource(value = DataSourceType.slave)
    Map<String, Object> selectGroup();
}

@Service
@RequiredArgsConstructor
public class UserService {
    private final UserMapper userMapper;
    private final GroupMapper groupMapper;

    public Map<String, Object> getUser(int id) {
        return userMapper.selectUser(id);
    }

    @DataSource(value = DataSourceType.slave)
    //@Transactional(rollbackFor = Exception.class)  // 如果需要事务，可添加
    public Map<String, Object> getUser2() {
        return groupMapper.selectGroup();
    }
}