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一.问题描述
Dubbo远程服务提供者抛出的自定义异常无法被消费方正常捕获，消费方捕获的自定义异常全部变成RuntimeException，使用起来很不方便。
二.原因分析
相关源码
/** Licensed to the Apache Software Foundation (ASF) under one or more* contributor license agreements. See the NOTICE file distributed with* this work for additional information regarding copyright ownership.* The ASF licenses this file to You under the Apache License, Version 2.0* (the "License"); you may not use this file except in compliance with* the License. You may obtain a copy of the License at** http://www.apache.org/licenses/LICENSE-2.0** Unless required by applicable law or agreed to in writing, software* distributed under the License is distributed on an "AS IS" BASIS,* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.* See the License for the specific language governing permissions and* limitations under the License.*/
package org.apache.dubbo.rpc.filter;import org.apache.dubbo.common.constants.CommonConstants;
import org.apache.dubbo.common.extension.Activate;
import org.apache.dubbo.common.logger.ErrorTypeAwareLogger;
import org.apache.dubbo.common.logger.LoggerFactory;
import org.apache.dubbo.common.utils.ReflectUtils;
import org.apache.dubbo.common.utils.StringUtils;
import org.apache.dubbo.rpc.Filter;
import org.apache.dubbo.rpc.Invocation;
import org.apache.dubbo.rpc.Invoker;
import org.apache.dubbo.rpc.Result;
import org.apache.dubbo.rpc.RpcContext;
import org.apache.dubbo.rpc.RpcException;
import org.apache.dubbo.rpc.service.GenericService;
import org.apache.dubbo.rpc.support.RpcUtils;import java.lang.reflect.Method;import static org.apache.dubbo.common.constants.LoggerCodeConstants.CONFIG_FILTER_VALIDATION_EXCEPTION;/*** ExceptionInvokerFilter* <p>* Functions:* <ol>* <li>unexpected exception will be logged in ERROR level on provider side. Unexpected exception are unchecked* exception not declared on the interface</li>* <li>Wrap the exception not introduced in API package into RuntimeException. Framework will serialize the outer exception but stringnize its cause in order to avoid of possible serialization problem on client side</li>* </ol>*/
@Activate(group = CommonConstants.PROVIDER)
public class ExceptionFilter implements Filter, Filter.Listener {private ErrorTypeAwareLogger logger = LoggerFactory.getErrorTypeAwareLogger(ExceptionFilter.class);@Overridepublic Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {return invoker.invoke(invocation);}@Overridepublic void onResponse(Result appResponse, Invoker<?> invoker, Invocation invocation) {if (appResponse.hasException() && GenericService.class != invoker.getInterface()) {try {Throwable exception = appResponse.getException();// directly throw if it's checked exceptionif (!(exception instanceof RuntimeException) && (exception instanceof Exception)) {return;}// directly throw if the exception appears in the signaturetry {Method method = invoker.getInterface().getMethod(RpcUtils.getMethodName(invocation), invocation.getParameterTypes());Class<?>[] exceptionClasses = method.getExceptionTypes();for (Class<?> exceptionClass : exceptionClasses) {if (exception.getClass().equals(exceptionClass)) {return;}}} catch (NoSuchMethodException e) {return;}// for the exception not found in method's signature, print ERROR message in server's log.logger.error(CONFIG_FILTER_VALIDATION_EXCEPTION, "", "","Got unchecked and undeclared exception which called by " + RpcContext.getServiceContext().getRemoteHost() +". service: " + invoker.getInterface().getName() + ", method: " + RpcUtils.getMethodName(invocation) +", exception: " + exception.getClass().getName() + ": " + exception.getMessage(), exception);// directly throw if exception class and interface class are in the same jar file.String serviceFile = ReflectUtils.getCodeBase(invoker.getInterface());String exceptionFile = ReflectUtils.getCodeBase(exception.getClass());if (serviceFile == null || exceptionFile == null || serviceFile.equals(exceptionFile)) {return;}// directly throw if it's JDK exceptionString className = exception.getClass().getName();if (className.startsWith("java.") || className.startsWith("javax.") || className.startsWith("jakarta.")) {return;}// directly throw if it's dubbo exceptionif (exception instanceof RpcException) {return;}// 这里把其它情况的异常都改为RuntimeException抛出// otherwise, wrap with RuntimeException and throw back to the clientappResponse.setException(new RuntimeException(StringUtils.toString(exception)));} catch (Throwable e) {logger.warn(CONFIG_FILTER_VALIDATION_EXCEPTION, "", "","Fail to ExceptionFilter when called by " + RpcContext.getServiceContext().getRemoteHost() +". service: " + invoker.getInterface().getName() + ", method: " + RpcUtils.getMethodName(invocation) +", exception: " + e.getClass().getName() + ": " + e.getMessage(), e);}}}@Overridepublic void onError(Throwable e, Invoker<?> invoker, Invocation invocation) {logger.error(CONFIG_FILTER_VALIDATION_EXCEPTION, "", "","Got unchecked and undeclared exception which called by " + RpcContext.getServiceContext().getRemoteHost() +". service: " + invoker.getInterface().getName() + ", method: " + RpcUtils.getMethodName(invocation) +", exception: " + e.getClass().getName() + ": " + e.getMessage(), e);}// For test purposepublic void setLogger(ErrorTypeAwareLogger logger) {this.logger = logger;}
}源码中只有以下几种情况会直接抛出异常
1. 非RuntimeException，直接抛出异常
2. 如果是checked异常，直接抛出
3. 在方法签名上有声明，直接抛出
4. 异常类和接口类在同一个jar包，直接抛出
5. 是JDK自带的包名以java、javax、jakarta开头的异常，直接抛出
6. 是dubbo本身的RpcException异常，直接抛出
这样的话那最简单的方案就是重写ExceptionFilter，在识别到我们程序自定义异常时也return就可以在消费端正常捕获并处理异常
三.解决方法
1.重写ExceptionFilter的onResponse方法
public class DubboExceptionFilter extends ExceptionFilter {private ErrorTypeAwareLogger logger = LoggerFactory.getErrorTypeAwareLogger(ExceptionFilter.class);/**redis校验异常 字符串*/private static final String REDIS_VALID_EXCEPTION_TEXT = "RedisValidException";@Overridepublic void onResponse(Result appResponse, Invoker<?> invoker, Invocation invocation) {if(!appResponse.hasException() || GenericService.class == invoker.getInterface()) {return;}try {Throwable exception = appResponse.getException();// directly throw if it's checked exceptionif (!(exception instanceof RuntimeException) && (exception instanceof Exception)) {return;}/*--------------------------------------自定义的异常处理--------------------------------------------*/if(exception instanceof BusinessFailException) {return;}//如果还有其它需要直接抛出的异常，也在这里处理/*--------------------------------------自定义的异常处理--------------------------------------------*/// directly throw if the exception appears in the signaturetry {Method method = invoker.getInterface().getMethod(invocation.getMethodName(), invocation.getParameterTypes());Class<?>[] exceptionClasses = method.getExceptionTypes();for (Class<?> exceptionClass : exceptionClasses) {if (exception.getClass().equals(exceptionClass)) {return;}}} catch (NoSuchMethodException e) {return;}// for the exception not found in method's signature, print ERROR message in server's log.logger.error(CONFIG_FILTER_VALIDATION_EXCEPTION, "", "", "Got unchecked and undeclared exception which called by " + RpcContext.getServiceContext().getRemoteHost() + ". service: " + invoker.getInterface().getName() + ", method: " + invocation.getMethodName() + ", exception: " + exception.getClass().getName() + ": " + exception.getMessage(), exception);// directly throw if exception class and interface class are in the same jar file.String serviceFile = ReflectUtils.getCodeBase(invoker.getInterface());String exceptionFile = ReflectUtils.getCodeBase(exception.getClass());if (serviceFile == null || exceptionFile == null || serviceFile.equals(exceptionFile)) {return;}// directly throw if it's JDK exceptionString className = exception.getClass().getName();if (className.startsWith("java.") || className.startsWith("javax.")) {return;}// directly throw if it's dubbo exceptionif (exception instanceof RpcException) {return;}// 除了以上所有的异常，其它异常都改为RuntimeException抛出appResponse.setException(new RuntimeException(StringUtils.toString(exception)));} catch (Throwable e) {logger.warn(CONFIG_FILTER_VALIDATION_EXCEPTION, "", "", "Fail to ExceptionFilter when called by " + RpcContext.getServiceContext().getRemoteHost() + ". service: " + invoker.getInterface().getName() + ", method: " + invocation.getMethodName() + ", exception: " + e.getClass().getName() + ": " + e.getMessage(), e);}}
}2.配置让自定义Filter生效
在服务提供方resources目录下创建META-INF/dubbo文件夹,在新建的文件夹下创建org.apache.dubbo.rpc.Filter文件，文件内容为
dubboExceptionFilter=你的包名.DubboExceptionFilter
3.修改配置
以properties配置为例
#自定义的异常捕获filter
dubbo.provider.filter=dubboExceptionFilter,-exception四.Dubbo版本>= 3.1.6的问题
dubbo 3.1.6以上版本提高了序列化安全检查强度，自定义的异常抛出时会因为安全问题无法序列化
配置文件中加入以下配置可解决
#检查模式级别改为WARN
dubbo.application.serialize-check-status=WARN问题参考
Dubbo新版本（＞3.2）序列化问题