SpringBoot自定义注解使用读写分离Mysql数据库的实例教程

		<dependency>
   <groupId>mysql</groupId>
   <artifactId>mysql-connector-java</artifactId>
   <version>8.0.16</version>
  </dependency>

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

/**
 * 数据源类型枚举
 * @author yangjc01
 * @create 2020/11/02
 */
public enum DataSourceType {
 /**
  * 主库，主要进行写操作
  */
 MASTER,
 /**
  * 从库，进行读操作
  */
 SLAVE
}

/**
 * 动态数据源
 * @author yangjc01
 * @create 2020/11/02
 */
public class DynamicDataSource extends AbstractRoutingDataSource {

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

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

public class DynamicDataSourceContextHolder {

 /**
  * 使用ThreadLocal维护变量，ThreadLocal为每个使用该变量的线程提供独立的变量副本，
  * 所以每一个线程都可以独立地改变自己的副本，而不会影响其它线程所对应的副本。
  */
 private static final ThreadLocal<String> CONTEXT_HOLDER = 
 new ThreadLocal<>();

 /**
  * 设置数据源的变量
  */
 public static void setDateSourceType(String dsType) {
  CONTEXT_HOLDER.set(dsType);
 }

 /**
  * 获得数据源的变量
  */
 public static String getDateSourceType() {
  return CONTEXT_HOLDER.get();
 }

 /**
  * 清空数据源变量
  */
 public static void clearDateSourceType() {
  CONTEXT_HOLDER.remove();
 }
}

/**
 * @author yangjc01
 * @create 2020/11/01
 */
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface DataSource {
 /**
  * 切换数据源
  */
 DataSourceType value() default DataSourceType.MASTER;

}

@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();
  }
 }
}

@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<Object, Object> targetDataSources = new HashMap<>();
  targetDataSources.put(DataSourceType.MASTER.name(), masterDataSource());
  targetDataSources.put(DataSourceType.SLAVE.name(), slaveDataSource());
  return new DynamicDataSource(masterDataSource(), targetDataSources);
 }
}

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

@DataSource(value = DataSourceType.SLAVE)

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