Java注解實(shí)現(xiàn)動(dòng)態(tài)數(shù)據(jù)源切換的實(shí)例代碼

/** 
 * Retrieve the current target DataSource. Determines the 
 * {@link #determineCurrentLookupKey() current lookup key}, performs 
 * a lookup in the {@link #setTargetDataSources targetDataSources} map, 
 * falls back to the specified 
 * {@link #setDefaultTargetDataSource default target DataSource} if necessary. 
 * @see #determineCurrentLookupKey() 
 */ 
protected DataSource determineTargetDataSource() { 
  Assert.notNull(this.resolvedDataSources, "DataSource router not initialized"); 
  Object lookupKey = determineCurrentLookupKey(); 
  DataSource dataSource = this.resolvedDataSources.get(lookupKey); 
  if (dataSource == null && (this.lenientFallback || lookupKey == null)) { 
    dataSource = this.resolvedDefaultDataSource; 
  } 
  if (dataSource == null) { 
    throw new IllegalStateException("Cannot determine target DataSource for lookup key [" + lookupKey + "]"); 
  } 
  return dataSource; 
}

/**
 * Created by huangyangquan on 2016/11/30.
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface DataSource {

  DataSourceType value();

}

/**
 * Created by huangyangquan on 2016/11/30.
 */
public enum DataSourceType {

  MASTER,
  SLAVE

}

/**
 * Created by huangyangquan on 2016/11/30.
 */
public class DynamicDataSource extends AbstractRoutingDataSource {

  @Override
  protected Object determineCurrentLookupKey() {
    return DynamicDataSourceHolder.getDataSourceType();
  }

}

/**
 * Created by huangyangquan on 2016/11/30.
 */
public class DynamicDataSourceHolder {

  // 線程本地環(huán)境
  private static final ThreadLocal<DataSourceType> contextHolder = new ThreadLocal<DataSourceType>();

  // 設(shè)置數(shù)據(jù)源類型
  public static void setDataSourceType(DataSourceType dataSourceType) {
    Assert.notNull(dataSourceType, "DataSourceType cannot be null");
    contextHolder.set(dataSourceType);
  }

  // 獲取數(shù)據(jù)源類型
  public static DataSourceType getDataSourceType() {
    return (DataSourceType) contextHolder.get();
  }

  // 清除數(shù)據(jù)源類型
  public static void clearDataSourceType() {
    contextHolder.remove();
  }

}

<bean id="spyGhotelDataSource" class="com.aheizi.config.DynamicDataSource">
  <property name="targetDataSources">
    <map key-type="java.lang.String">
      <entry key="MASTER" value-ref="TEST-MASTER-DB"></entry>
      <entry key="SLAVE" value-ref="TEST-SLAVE-DB"></entry>
    </map>
  </property>
  <property name="defaultTargetDataSource" ref="TEST-MASTER-DB">
  </property>
</bean>

<aop:aspectj-autoproxy proxy-target-class="false" />
<bean id="manyDataSourceAspect" class="com.aheizi.config.DataSourceAspect" />
<aop:config>
  <aop:aspect id="dataSourceCut" ref="manyDataSourceAspect">
    <aop:pointcut expression="execution(* com.aheizi.dao.*.*(..))"
      id="dataSourceCutPoint" /><!-- 配置切點(diǎn) -->
    <aop:before pointcut-ref="dataSourceCutPoint" method="before" />
  </aop:aspect>
</aop:config>

/**
 * Created by huangyangquan on 2016/11/30.
 */
public class DataSourceAspect {

  private static final Logger LOG = LoggerFactory.getLogger(DataSourceAspect.class);

  public void before(JoinPoint point){
    Object target = point.getTarget();
    String method = point.getSignature().getName();
    Class<?>[] classz = target.getClass().getInterfaces();
    Class<?>[] parameterTypes = ((MethodSignature) point.getSignature()).getMethod().getParameterTypes();
    try {
      Method m = classz[0].getMethod(method, parameterTypes);
      if (m != null && m.isAnnotationPresent(DataSource.class)) {
        // 訪問mapper中的注解
        DataSource data = m.getAnnotation(DataSource.class);
        switch (data.value()) {
          case MASTER:
            DynamicDataSourceHolder.setDataSourceType(DataSourceType.MASTER);
            LOG.info("using dataSource:{}", DataSourceType.MASTER);
            break;
          case SLAVE:
            DynamicDataSourceHolder.setDataSourceType(DataSourceType.SLAVE);
            LOG.info("using dataSource:{}", DataSourceType.SLAVE);
            break;
        }
      }
    } catch (Exception e) {
      LOG.error("dataSource annotation error:{}", e.getMessage());
      // 若出現(xiàn)異常，手動(dòng)設(shè)為主庫
      DynamicDataSourceHolder.setDataSourceType(DataSourceType.MASTER);
    }
  }

}