SpringBoot+aop实现主从数据库的读写分离操作
作者:A尘埃
读写分离的作用是为了缓解写库,也就是主库的压力,但一定要基于数据一致性的原则,就是保证主从库之间的数据一定要一致,这篇文章给大家介绍SpringBoot+aop实现主从数据库的读写分离操作,感兴趣的朋友跟随小编一起看看吧
读写分离的作用是为了缓解写库,也就是主库的压力,但一定要基于数据一致性的原则,就是保证主从库之间的数据一定要一致。如果一个方法涉及到写的逻辑,那么该方法里所有的数据库操作都要走主库。
一、环境部署
- 数据库:MySql
- 2个,一主一从
DROP TABLE IF EXISTS `user`; CREATE TABLE `user` ( `user_id` bigint(20) NOT NULL COMMENT '用户id', `user_name` varchar(255) DEFAULT '' COMMENT '用户名称', `user_phone` varchar(50) DEFAULT '' COMMENT '用户手机', `address` varchar(255) DEFAULT '' COMMENT '住址', `weight` int(3) NOT NULL DEFAULT '1' COMMENT '权重,大者优先', `created_at` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间', `updated_at` datetime DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '更新时间', PRIMARY KEY (`user_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; INSERT INTO `user` VALUES ('1196978513958141952', '测试1', '18826334748', '广州市海珠区', '1', '2019-11-20 10:28:51', '2019-11-22 14:28:26'); INSERT INTO `user` VALUES ('1196978513958141953', '测试2', '18826274230', '广州市天河区', '2', '2019-11-20 10:29:37', '2019-11-22 14:28:14'); INSERT INTO `user` VALUES ('1196978513958141954', '测试3', '18826273900', '广州市天河区', '1', '2019-11-20 10:30:19', '2019-11-22 14:28:30');
二、依赖
<dependencies> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid-spring-boot-starter</artifactId> <version>1.1.10</version> </dependency> <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>1.3.2</version> </dependency> <dependency> <groupId>tk.mybatis</groupId> <artifactId>mapper-spring-boot-starter</artifactId> <version>2.1.5</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.16</version> </dependency> <!-- 动态数据源 所需依赖 ### start--> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-jdbc</artifactId> <scope>provided</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-aop</artifactId> <scope>provided</scope> </dependency> <!-- 动态数据源 所需依赖 ### end--> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <optional>true</optional> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>1.2.4</version> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> </dependencies>
三、application.yml配置主从数据源
server: port: 8001 spring: jackson: date-format: yyyy-MM-dd HH:mm:ss time-zone: GMT+8 datasource: type: com.alibaba.druid.pool.DruidDataSource driver-class-name: com.mysql.cj.jdbc.Driver master: url: jdbc:mysql://127.0.0.1:3307/user?serverTimezone=Asia/Shanghai&useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&failOverReadOnly=false&useSSL=false&zeroDateTimeBehavior=convertToNull&allowMultiQueries=true username: root password: slave: url: jdbc:mysql://127.0.0.1:3308/user?serverTimezone=Asia/Shanghai&useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&failOverReadOnly=false&useSSL=false&zeroDateTimeBehavior=convertToNull&allowMultiQueries=true username: root password:
四、Config配置
@Getter public enum DynamicDataSourceEnum { MASTER("master"), SLAVE("slave"); private String dataSourceName; DynamicDataSourceEnum(String dataSourceName) { this.dataSourceName = dataSourceName; } }
@Configuration @MapperScan(basePackages = "com.xjt.proxy.mapper", sqlSessionTemplateRef = "sqlTemplate") public class DataSourceConfig{ //主库 @Bean @ConfigurationProperties(prefix = "spring.datasource.master") public DataSource masterDb(){ return DruidDataSourceBuilder.create().build(); } //从库 @Bean @ConditionalOnProperty(prefix = "spring.datasource", name = "slave", matchIfMissing = true) @ConfigurationProperties(prefix = "spring.datasource.slave") public DataSource slaveDb() { return DruidDataSourceBuilder.create().build(); } //主从动态配置 @Bean public DynamicDataSource dynamicDb(@Qualifier("masterDb") DataSource masterDataSource, @Autowired(required = false) @Qualifier("slaveDb") DataSource slaveDataSource){ DynamicDataSource dynamicDataSource = new DynamicDataSource(); Map<Object,Object> targetDataSources = new HashMap<>(); targetDataSources.put(DynamicDataSourceEnum.MASTER.getDataSourceName(), masterDataSource); if(slaveDataSource != null){ targetDataSources.put(DynamicDataSourceEnum.SLAVE.getDataSourceName(), slaveDataSource); } dynamicDataSource.setTargetDataSources(targetDataSources); dynamicDataSource.setDefaultTargetDataSource(masterDataSource); return dynamicDataSource; } @Bean public SqlSessionFactory sessionFactory(){ SqlSessionFactoryBean bean = new SqlSessionFactoryBean(); bean.setMapperLocations( new PathMatchingResourcePatternResolver().getResources("classpath*:mapper/*Mapper.xml")); bean.setDataSource(dynamicDataSource); return bean.getObject(); } @Bean public SqlSessionTemplate sqlTemplate(){ return new SqlSessionTemplate(sqlSessionFactory); } @Bean(name = "dataourceTx") public DataSourceTransactionManager dataSourceTx(){ DataSourceTransactionManager dataSourceTransactionManager = new DataSourceTransactionManager(); dataSourceTransactionManager.setDataSource(dynamicDataSource); return dataSourceTransactionManager; } }
五、设置路由
为了方便查找对应的数据源,我们可以用ThreadLocal保存数据源的信息到每个线程中,方便我们需要时获取
pubic class DataSourceContextHolder{ private static final ThreadLocal<String> DYNAMIC_DATASOURCE_CONTEXT = new ThreadLocal<>(); public static void set(String datasourceType) { DYNAMIC_DATASOURCE_CONTEXT.set(datasourceType); } public static String get() { return DYNAMIC_DATASOURCE_CONTEXT.get(); } public static void clear() { DYNAMIC_DATASOURCE_CONTEXT.remove(); } }
AbstractRoutingDataSource的作用是基于查找key路由到对应的数据源,它内部维护了一组目标数据源,并且做了路由key与目标数据源之间的映射,提供基于key查找数据源的方法。
public class DynamicDataSource extends AbstractRoutingDataSource { @Override protected Object determineCurrentLookupKey() { return DataSourceContextHolder.get(); } }
六、数据源的注解
方便切换数据源,注解中包含数据源对应的枚举值,默认是主库
@Retention(RetentionPolicy.RUNTIME) @Target(ElementType.METHOD) @Documented public @interface DataSourceSelector { DynamicDataSourceEnum value() default DynamicDataSourceEnum.MASTER; boolean clear() default true; }
七、Aop切换数据源
定义一个aop类,对有注解的方法做切换数据源的操作
@Slf4j @Aspect @Order(value = 1) @Component public class DataSourceContextAop { @Around("@annotation(com.xjt.proxy.dynamicdatasource.DataSourceSelector)") public Object setDynamicDataSource(ProceedingJoinPoint pjp) throws Throwable { boolean clear = true; try { Method method = this.getMethod(pjp); DataSourceSelector dataSourceImport = method.getAnnotation(DataSourceSelector.class);//获取注解标注的方法 clear = dataSourceImport.clear(); DataSourceContextHolder.set(dataSourceImport.value().getDataSourceName()); log.info("========数据源切换至:{}", dataSourceImport.value().getDataSourceName()); return pjp.proceed(); } finally { if (clear) { DataSourceContextHolder.clear(); } } } private Method getMethod(JoinPoint pjp) { MethodSignature signature = (MethodSignature)pjp.getSignature(); return signature.getMethod(); } }
八、测试
写好Service文件,包含读取和更新两个方法
@Service public class UserService { @Autowired private UserMapper userMapper; @DataSourceSelector(value = DynamicDataSourceEnum.SLAVE) public List<User> listUser() { List<User> users = userMapper.selectAll(); return users; } @DataSourceSelector(value = DynamicDataSourceEnum.MASTER) public int update() { User user = new User(); user.setUserId(Long.parseLong("1196978513958141952")); user.setUserName("修改后的名字2"); return userMapper.updateByPrimaryKeySelective(user); } @DataSourceSelector(value = DynamicDataSourceEnum.SLAVE) public User find() { User user = new User(); user.setUserId(Long.parseLong("1196978513958141952")); return userMapper.selectByPrimaryKey(user); } }
根据方法上的注解可以看出,读的方法走从库,更新的方法走主库,更新的对象是userId为1196978513958141953 的数据
@RunWith(SpringRunner.class) @SpringBootTest class UserServiceTest { @Autowired UserService userService; @Test void listUser() { List<User> users = userService.listUser(); for (User user : users) { System.out.println(user.getUserId()); System.out.println(user.getUserName()); System.out.println(user.getUserPhone()); } } @Test void update() { userService.update(); User user = userService.find(); System.out.println(user.getUserName()); } }
读取方法
更新方法
执行之后,比对数据库就可以发现主从库都修改了数据,说明我们的读写分离是成功的。当然,更新方法可以指向从库,这样一来就只会修改到从库的数据,而不会涉及到主库。
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