SpringBoot自定义注解使用读写分离Mysql数据库的实例教程

需求场景

为了防止代码中有的SQL慢查询，影响我们线上主数据库的性能。我们需要将sql查询操作切换到从库中进行。为了使用方便，将自定义注解的形式使用。

mysql导入的依赖

		
   mysql
   mysql-connector-java
   8.0.16
  

代码实现

配置文件

application.yml

spring:
 datasource:
 master:
  username: root
  password: 123456
  jdbc-url: jdbc:mysql://localhost:3306/master?useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8
  driver-class-name: com.mysql.cj.jdbc.Driver
 slave:
  username: root
  password: 123456
  jdbc-url: jdbc:mysql://localhost:3306/slave?useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8
  driver-class-name: com.mysql.cj.jdbc.Driver

DataSourceType

public enum DataSourceType {
 
 MASTER,
 
 SLAVE
}

DynamicDataSource

public class DynamicDataSource extends AbstractRoutingDataSource {

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

 @Override
 protected Object determineCurrentLookupKey() {
  return DynamicDataSourceContextHolder.getDateSourceType();
 }
}

DynamicDataSourceContextHolder

public class DynamicDataSourceContextHolder {

 
 private static final ThreadLocal CONTEXT_HOLDER = 
 new ThreadLocal<>();

 
 public static void setDateSourceType(String dsType) {
  CONTEXT_HOLDER.set(dsType);
 }

 
 public static String getDateSourceType() {
  return CONTEXT_HOLDER.get();
 }

 
 public static void clearDateSourceType() {
  CONTEXT_HOLDER.remove();
 }
}

DataSource 注解

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

}

DataSourceAspect 切面

@Aspect
@Order(1)
@Component
public class DataSourceAspect {

 @Pointcut("@annotation(com.jgame.mis.annotation.DataSource)")
 public void dsPointCut() {

 }

 @Around("dsPointCut()")
 public Object around(ProceedingJoinPoint point) throws Throwable {
  MethodSignature signature = (MethodSignature) point.getSignature();

  Method method = signature.getMethod();

  DataSource dataSource = method.getAnnotation(DataSource.class);

  if (null!=dataSource) {
   DynamicDataSourceContextHolder.
   setDateSourceType(dataSource.value().name());
  }

  try {
   return point.proceed();
  } finally {
   // 销毁数据源 在执行方法之后
   DynamicDataSourceContextHolder.clearDateSourceType();
  }
 }
}

DataSourceConfig

@Configuration
public class DataSourceConfig {

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

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

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

启动类上添加注解

@import({DataSourceConfig.class})
@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})

需要使用的方法上

@DataSource(value = DataSourceType.SLAVE)

DEMO

	@Select("select * from user")
  @DataSource(value = DataSourceType.SLAVE)
  List selectUserList();

总结

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