Spring @Cacheable redis異常不影響正常業(yè)務(wù)方案

更新時間：2021年02月19日 08:36:58 作者：神農(nóng)L

這篇文章主要介紹了Spring @Cacheable redis異常不影響正常業(yè)務(wù)方案,文中通過示例代碼介紹的非常詳細(xì)，對大家的學(xué)習(xí)或者工作具有一定的參考學(xué)習(xí)價值，需要的朋友們下面隨著小編來一起學(xué)習(xí)學(xué)習(xí)吧

背景

項目中,使用@Cacheable進(jìn)行數(shù)據(jù)緩存。發(fā)現(xiàn)：當(dāng)redis宕機(jī)之后，@Cacheable注解的方法并未進(jìn)行緩存沖突，而是直接拋出異常。而這樣的異常會導(dǎo)致服務(wù)不可用。

原因分析

我們是通過@EnableCaching進(jìn)行緩存啟用的，因此可以先看@EnableCaching的相關(guān)注釋

通過@EnableCaching的類注釋可發(fā)現(xiàn),spring cache的核心配置接口為：org.springframework.cache.annotation.CachingConfigurer

/**
 * Interface to be implemented by @{@link org.springframework.context.annotation.Configuration
 * Configuration} classes annotated with @{@link EnableCaching} that wish or need to
 * specify explicitly how caches are resolved and how keys are generated for annotation-driven
 * cache management. Consider extending {@link CachingConfigurerSupport}, which provides a
 * stub implementation of all interface methods.
 *
 * <p>See @{@link EnableCaching} for general examples and context; see
 * {@link #cacheManager()}, {@link #cacheResolver()} and {@link #keyGenerator()}
 * for detailed instructions.
 *
 * @author Chris Beams
 * @author Stephane Nicoll
 * @since 3.1
 * @see EnableCaching
 * @see CachingConfigurerSupport
 */
public interface CachingConfigurer {

 /**
 * Return the cache manager bean to use for annotation-driven cache
 * management. A default {@link CacheResolver} will be initialized
 * behind the scenes with this cache manager. For more fine-grained
 * management of the cache resolution, consider setting the
 * {@link CacheResolver} directly.
 * <p>Implementations must explicitly declare
 * {@link org.springframework.context.annotation.Bean @Bean}, e.g.
 * <pre class="code">
 * Configuration
 * EnableCaching
 * public class AppConfig extends CachingConfigurerSupport {
 *  Bean // important!
 *  Override
 *  public CacheManager cacheManager() {
 *   // configure and return CacheManager instance
 *  }
 *  // ...
 * }
 * </pre>
 * See @{@link EnableCaching} for more complete examples.
 */
 CacheManager cacheManager();

 /**
 * Return the {@link CacheResolver} bean to use to resolve regular caches for
 * annotation-driven cache management. This is an alternative and more powerful
 * option of specifying the {@link CacheManager} to use.
 * <p>If both a {@link #cacheManager()} and {@code #cacheResolver()} are set,
 * the cache manager is ignored.
 * <p>Implementations must explicitly declare
 * {@link org.springframework.context.annotation.Bean @Bean}, e.g.
 * <pre class="code">
 * Configuration
 * EnableCaching
 * public class AppConfig extends CachingConfigurerSupport {
 *  Bean // important!
 *  Override
 *  public CacheResolver cacheResolver() {
 *   // configure and return CacheResolver instance
 *  }
 *  // ...
 * }
 * </pre>
 * See {@link EnableCaching} for more complete examples.
 */
 CacheResolver cacheResolver();

 /**
 * Return the key generator bean to use for annotation-driven cache management.
 * Implementations must explicitly declare
 * {@link org.springframework.context.annotation.Bean @Bean}, e.g.
 * <pre class="code">
 * Configuration
 * EnableCaching
 * public class AppConfig extends CachingConfigurerSupport {
 *  Bean // important!
 *  Override
 *  public KeyGenerator keyGenerator() {
 *   // configure and return KeyGenerator instance
 *  }
 *  // ...
 * }
 * </pre>
 * See @{@link EnableCaching} for more complete examples.
 */
 KeyGenerator keyGenerator();

 /**
 * Return the {@link CacheErrorHandler} to use to handle cache-related errors.
 * <p>By default,{@link org.springframework.cache.interceptor.SimpleCacheErrorHandler}
 * is used and simply throws the exception back at the client.
 * <p>Implementations must explicitly declare
 * {@link org.springframework.context.annotation.Bean @Bean}, e.g.
 * <pre class="code">
 * Configuration
 * EnableCaching
 * public class AppConfig extends CachingConfigurerSupport {
 *  Bean // important!
 *  Override
 *  public CacheErrorHandler errorHandler() {
 *   // configure and return CacheErrorHandler instance
 *  }
 *  // ...
 * }
 * </pre>
 * See @{@link EnableCaching} for more complete examples.
 */
 CacheErrorHandler errorHandler();

}

該接口errorHandler方法可配置異常的處理方式。通過該方法上的注釋可以發(fā)現(xiàn),默認(rèn)的CacheErrorHandler實現(xiàn)類是org.springframework.cache.interceptor.SimpleCacheErrorHandler

/**
 * A simple {@link CacheErrorHandler} that does not handle the
 * exception at all, simply throwing it back at the client.
 *
 * @author Stephane Nicoll
 * @since 4.1
 */
public class SimpleCacheErrorHandler implements CacheErrorHandler {

 @Override
 public void handleCacheGetError(RuntimeException exception, Cache cache, Object key) {
 throw exception;
 }

 @Override
 public void handleCachePutError(RuntimeException exception, Cache cache, Object key, Object value) {
 throw exception;
 }

 @Override
 public void handleCacheEvictError(RuntimeException exception, Cache cache, Object key) {
 throw exception;
 }

 @Override
 public void handleCacheClearError(RuntimeException exception, Cache cache) {
 throw exception;
 }
}

SimpleCacheErrorHandler類注釋上說明的很清楚：對cache的異常不做任何處理，直接將該異常拋給客戶端。因此默認(rèn)的情況下，redis服務(wù)器異常后，直接就阻斷了正常業(yè)務(wù)

解決方案

通過上面的分析可知，我們可以通過自定義CacheErrorHandler來干預(yù)@Cacheable的異常處理邏輯。具體代碼如下：

public class RedisConfig extends CachingConfigurerSupport {

  /**
   * redis數(shù)據(jù)操作異常處理。該方法處理邏輯：在日志中打印出錯誤信息，但是放行。
   * 保證redis服務(wù)器出現(xiàn)連接等問題的時候不影響程序的正常運行
   */
  @Override
  public CacheErrorHandler errorHandler() {
    return new CacheErrorHandler() {
      @Override
      public void handleCachePutError(RuntimeException exception, Cache cache,
                      Object key, Object value) {
        handleRedisErrorException(exception, key);
      }

      @Override
      public void handleCacheGetError(RuntimeException exception, Cache cache,
                      Object key) {
        handleRedisErrorException(exception, key);
      }

      @Override
      public void handleCacheEvictError(RuntimeException exception, Cache cache,
                       Object key) {
        handleRedisErrorException(exception, key);
      }

      @Override
      public void handleCacheClearError(RuntimeException exception, Cache cache) {
        handleRedisErrorException(exception, null);
      }
    };
  }

  protected void handleRedisErrorException(RuntimeException exception, Object key) {
    log.error("redis異常：key=[{}]", key, exception);
  }
}

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