【spring boot】mybatis基于注解方式实现双数据源配置

川长思鸟来 2024-04-19 12:28 65阅读 0赞

当我们的项目需要同时连接2个数据库时，这时就要用来双数据源的配置了

网上有很多实现方法，相比较来说基于注解方式是最优雅的一种方式了，

这次我就讲下**mybatis基于注解方式实现双数据源配置**

### 第一步：在配置文件中增加如下配置项 ###

spring:
      jmx:
        default-domain: mybatis
      datasource:
        db1:
          jdbc-url: jdbc:mysql://localhost:3306/mybatis-demo?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai
          username: root
          password: root
          driver-class-name: com.mysql.cj.jdbc.Driver
          max-idle: 10
          max-wait: 10000
          min-idle: 5
          initial-size: 5
          dialect: mysql
        db2:
          jdbc-url: jdbc:mysql://localhost:3306/mybatis-demo?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai
          username: root
          password: root
          driver-class-name: com.mysql.cj.jdbc.Driver
          max-idle: 10
          max-wait: 10000
          min-idle: 5
          initial-size: 5
          dialect: mysql
    mybatis:
      typeAliasesPackage: com.wg.demo.po
      mapper-locations: classpath*:mapper/*.xml
      configuration:
        cache-enabled: true

配置了2个数据源，db1和db2

### 第二步：实现基于注解数据源动态切换 ###

DataSourceConfig负责加载配置文件中数据源的配置信息

/** * @Author: wanggang.io * @Date: 2018/12/28 9:50 * @todo */
    @Configuration
    public class DataSourceConfig { 
        //数据源1
        @Bean(name = "db1")
        @ConfigurationProperties(prefix = "spring.datasource.db1") // application.properteis中对应属性的前缀
        public DataSource dataSource1() { 
            return DataSourceBuilder.create().build();
        }
    
        //数据源2
        @Bean(name = "db2")
        @ConfigurationProperties(prefix = "spring.datasource.db2") // application.properteis中对应属性的前缀
        public DataSource dataSource2() { 
            return DataSourceBuilder.create().build();
        }
    
        /** * 动态数据源: 通过AOP在不同数据源之间动态切换 * @return */
        @Primary
        @Bean(name = "dynamicDataSource")
        public DataSource dynamicDataSource() { 
            DynamicDataSource dynamicDataSource = new DynamicDataSource();
            // 默认数据源
            dynamicDataSource.setDefaultTargetDataSource(dataSource1());
            // 配置多数据源
            Map<Object, Object> dsMap = new HashMap();
            dsMap.put("db1", dataSource1());
            dsMap.put("db2", dataSource2());
    
            dynamicDataSource.setTargetDataSources(dsMap);
            return dynamicDataSource;
        }
    
        /** * 配置@Transactional注解事物 * @return */
        @Bean
        public PlatformTransactionManager transactionManager() { 
            return new DataSourceTransactionManager(dynamicDataSource());
        }
    }

DataSourceContextHolder用来获取及设置当前数据源

/** * @Author: wanggang.io * @Date: 2018/12/28 9:50 * @todo */
    public class DataSourceContextHolder { 
        static  Logger  logger = LoggerFactory.getLogger("DataSourceContextHolder");
        /** * 默认数据源 */
        public static final String DEFAULT_DS = DataSourceEnum.DB1.getValue();
    
        private static final ThreadLocal<String> contextHolder = new ThreadLocal<>();
    
        // 设置数据源名
        public static void setDB(String dbType) { 
            contextHolder.set(dbType);
        }
    
        // 获取数据源名
        public static String getDB() { 
            String dbsource = contextHolder.get();
            if(dbsource == null ){ 
                dbsource = "db1";
                logger.info("数据源为NULL 返回默认数据源"+ dbsource);
            }
            return  dbsource;
        }
    
        // 清除数据源名
        public static void clearDB() { 
            contextHolder.remove();
        }
    }

枚举类

public enum DataSourceEnum { 
    
        DB1("db1"),DB2("db2");
    
        private String value;
    
        DataSourceEnum(String value){ this.value=value;}
    
        public String getValue() { 
            return value;
        }
    }

自定义DS注解

/** * @Author: wanggang.io * @Date: 2018/12/28 9:50 * @todo 自定义注解 */
    @Retention(RetentionPolicy.RUNTIME)
    @Target({ ElementType.METHOD})
    public @interface DS { 
        String value() default "db1";
    }

注解切面类，根据接口上的注解动态切换数据源

/** * @Author: wanggang.io * @Date: 2018/12/28 15:50 * @todo自定义注解 + AOP的方式实现数据源动态切换。 */
    
    @Aspect
    @Component
    public class DynamicDataSourceAspect { 
        private Logger logger = LoggerFactory.getLogger(getClass().getName());
    
        public DynamicDataSourceAspect() { }
    
        @Before("@annotation(DS)")
        public void beforeSwitchDS(JoinPoint point) { 
            try { 
                Object methodInvocation = FunUtil.getPrivateField(point, "methodInvocation", point.getClass());
                Method method = (Method) FunUtil.getPrivateField(methodInvocation, "method", methodInvocation.getClass());
                DS annotation = method.getAnnotation(DS.class);
                DataSourceContextHolder.setDB(annotation.value());
            } catch (Exception e) { 
                e.printStackTrace();
            }
            logger.info("当前数据源为" + DataSourceContextHolder.getDB());
        }
    
        @After("@annotation(DS)")
        public void afterSwitchDS(JoinPoint point) { 
            DataSourceContextHolder.clearDB();
        }
    }

动态数据源，重载函数用于返回当前数据源

public class DynamicDataSource extends AbstractRoutingDataSource { 
        private Logger logger = LoggerFactory.getLogger(getClass().getName());
        @Override
        protected Object determineCurrentLookupKey() { 
            String dbsource = DataSourceContextHolder.getDB();
            if(dbsource == null ){ 
                dbsource = "db1";
                logger.info("数据源为NULL 返回数据源"+DataSourceContextHolder.getDB());
            }
            return dbsource;
        }
    }

其他工具类：

public class FunUtil { 
        public static Object getPrivateField(Object obj, String fieldName, Class classs) { 
            try { 
                Field field = classs.getDeclaredField(fieldName);
                field.setAccessible(true);
                return field.get(obj);
            } catch (Exception e) { 
                try { 
                    classs = classs.getSuperclass();
                    Field field = classs.getDeclaredField(fieldName);
                    field.setAccessible(true);
                    return field.get(obj);
                } catch (Exception ex) { 
                    return null;
                }
            }
        }
    }

### 第三步：禁止springboot自动注入数据源配置 ###

@SpringBootApplication(exclude = { DataSourceAutoConfiguration.class}/*禁止springboot自动注入数据源配置*/)
    @MapperScan({ "com.wg.demo.dao"})
    @EnableTransactionManagement
    @EnableCaching
    public class MybatisApplication { 
    
        public static void main(String[] args) { 
            SpringApplication.run(MybatisApplication.class, args);
        }
    
    }

### 使用方法： ###

Mapper接口文件定义2个接口,分别对应2个数据源的查询操作

@DS(“db1”) 表示该查询使用的是数据源1

@DS(“db2”) 表示该查询使用的是数据源2

@DS("db1")
        Employee selectFromDb1(Long id);
    
        @DS("db2")
        Employee selectFromDb2(Long id);

XML定义如下：

<select id="selectFromDb2" parameterType="java.lang.Long" resultMap="BaseResultMap">
        select
        <include refid="Base_Column_List" />
        from employee
        where id = #{id,jdbcType=BIGINT}
      </select>
      <select id="selectFromDb1" parameterType="java.lang.Long" resultMap="BaseResultMap">
        select
        <include refid="Base_Column_List" />
        from employee
        where id = #{id,jdbcType=BIGINT}
      </select>

controller层定义如下：

@ApiOperation(value = "从数据源1查询")
        @GetMapping("getfromdb1")
        public ResultMsg getEmployeeFromDb1(Long id){ 
            return ResultMsg.getMsg(employeeMapper.selectFromDb1(id));
        }
    
        @ApiOperation(value = "从数据源2查询")
        @GetMapping("getfromdb2")
        public ResultMsg getEmployeeFromDb2(Long id){ 
            return ResultMsg.getMsg(employeeMapper.selectFromDb2(id));
        }

运行项目，打开swagger开始测试  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2JkcXhfMDA3_size_16_color_FFFFFF_t_70]

console打印信息如下：

2019-09-18 11:26:43.645  INFO 1952 --- [nio-9393-exec-7] com.wg.demo.common.aop.LogAspect         : Request : {url='http://localhost:9393/mybatis/employee/getfromdb1', ip='0:0:0:0:0:0:0:1', classMethod='com.wg.demo.controller.EmployeeController.getEmployeeFromDb1', args=[1]}
    2019-09-18 11:26:43.646  INFO 1952 --- [nio-9393-exec-7] com.wg.demo.common.aop.LogAspect         : request Param: [1]
    2019-09-18 11:26:43.653  INFO 1952 --- [nio-9393-exec-7] c.w.d.c.d.DynamicDataSourceAspect        : 当前数据源为db1
    
    2019-09-18 11:26:44.207 DEBUG 1952 --- [nio-9393-exec-7] c.w.d.dao.EmployeeMapper.selectFromDb1   : ==>  Preparing: select id, name, age, gender, dept_id, address, create_time from employee where id = ? 
    2019-09-18 11:26:44.228 DEBUG 1952 --- [nio-9393-exec-7] c.w.d.dao.EmployeeMapper.selectFromDb1   : ==> Parameters: 1(Long)
    2019-09-18 11:26:44.268 DEBUG 1952 --- [nio-9393-exec-7] c.w.d.dao.EmployeeMapper.selectFromDb1   : <==      Total: 1
                                                                                                       2019-09-18 11:31:33.066  INFO 1952 --- [nio-9393-exec-9] com.wg.demo.common.aop.LogAspect         : Request : {url='http://localhost:9393/mybatis/employee/getfromdb2', ip='0:0:0:0:0:0:0:1', classMethod='com.wg.demo.controller.EmployeeController.getEmployeeFromDb2', args=[2]}
    2019-09-18 11:31:33.082  INFO 1952 --- [nio-9393-exec-9] com.wg.demo.common.aop.LogAspect         : request Param: [2]
    2019-09-18 11:31:33.082  INFO 1952 --- [nio-9393-exec-9] c.w.d.c.d.DynamicDataSourceAspect        : 当前数据源为db2
    2019-09-18 11:31:33.082  INFO 1952 --- [nio-9393-exec-9] com.zaxxer.hikari.HikariDataSource       : HikariPool-2 - Starting...
    2019-09-18 11:31:33.088  INFO 1952 --- [nio-9393-exec-9] com.zaxxer.hikari.HikariDataSource       : HikariPool-2 - Start completed.
    2019-09-18 11:31:33.088 DEBUG 1952 --- [nio-9393-exec-9] c.w.d.dao.EmployeeMapper.selectFromDb2   : ==>  Preparing: select id, name, age, gender, dept_id, address, create_time from employee where id = ?

通过日志可以看到数据源切换正常

至此完毕，喜欢的朋友记得点赞哦

项目地址：  
https://github.com/wanggang-git/Mybatis\_demo/tree/master/mybatis-demo%E5%8F%8C%E6%95%B0%E6%8D%AE%E6%BA%90

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