public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {
try {
Result result = invoker.invoke(invocation);
if (result.hasException() && GenericService.class != invoker.getInterface()) {
try {
Throwable exception = result.getException();
// directly throw if it's checked exception
if (!(exception instanceof RuntimeException) && (exception instanceof Exception)) {
return result;
}
// directly throw if the exception appears in the signature
try {
Method method = invoker.getInterface().getMethod(invocation.getMethodName(), invocation.getParameterTypes());
Class<?>[] exceptionClassses = method.getExceptionTypes();
for (Class<?> exceptionClass : exceptionClassses) {
if (exception.getClass().equals(exceptionClass)) {
return result;
}
}
} catch (NoSuchMethodException e) {
return result;
}
// for the exception not found in method's signature, print ERROR message in server's log.
logger.error("Got unchecked and undeclared exception which called by " + RpcContext.getContext().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 result;
}
// directly throw if it's JDK exception
String className = exception.getClass().getName();
if (className.startsWith("java.") || className.startsWith("javax.")) {
return result;
}
// directly throw if it's dubbo exception
if (exception instanceof RpcException) {
return result;
}
// otherwise, wrap with RuntimeException and throw back to the client
return new RpcResult(new RuntimeException(StringUtils.toString(exception)));
} catch (Throwable e) {
logger.warn("Fail to ExceptionFilter when called by " + RpcContext.getContext().getRemoteHost()
+ ". service: " + invoker.getInterface().getName() + ", method: " + invocation.getMethodName()
+ ", exception: " + e.getClass().getName() + ": " + e.getMessage(), e);
return result;
}
}
return result;
} catch (RuntimeException e) {
logger.error("Got unchecked and undeclared exception which called by " + RpcContext.getContext().getRemoteHost()
+ ". service: " + invoker.getInterface().getName() + ", method: " + invocation.getMethodName()
+ ", exception: " + e.getClass().getName() + ": " + e.getMessage(), e);
throw e;
}
從源碼中可以看出,異常直接返回有以下幾種情況
- 拋出的是一個Exception 而非 RuntimeException
- 在方法簽名上有聲明
- 異常類和接口聲明在同一個包裏
- 是JDK 自身異常
- 是dubbo 自身異常
由以上幾種情況可以看出可以有以下幾種解決方案
- 在方法簽名上throws 異常
- 將異常類和接口聲明放在同一個類中(推薦,適用於新項目和小項目改造)
- 重寫dubbo 的異常處理類ExceptionFilter(參考文章 https://www.jianshu.com/p/7e7076212bd0)
問題產生原因:
- 防止異常序列化失敗,拋出異常後Consumer沒有相應的異常類型進行接收