先看一段代码
public class GreeterImpl extends GreeterGrpc.GreeterImplBase {
@Override
public void sayHello(HelloRequest req, StreamObserver<HelloReply> responseObserver) {
if (Strings.isNullOrEmpty(req.getName())) {
throw new IllegalArgumentException("Missing name");
}
HelloReply reply = HelloReply.newBuilder().setMessage("Hello " + req.getName()).build();
responseObserver.onNext(reply);
responseObserver.onCompleted();
}
}
客户端调用的时候会抛出异常
HelloRequest request = HelloRequest.newBuilder().build();
HelloReply response = blockingStub.sayHello(request);
Exception in thread "main" io.grpc.StatusRuntimeException: UNKNOWN
我们可以看到异常并没有提供任何有用的信息。
我们可以在server端通过拦截器，捕获所有运行时异常，并返回更多的异常信息给调用方
public class GlobalGrpcExceptionHandler implements ServerInterceptor {
@Override
public <ReqT, RespT> ServerCall.Listener<ReqT> interceptCall(ServerCall<ReqT, RespT> call,
Metadata requestHeaders, ServerCallHandler<ReqT, RespT> next) {
ServerCall.Listener<ReqT> delegate = next.startCall(call, requestHeaders);
return new ExceptionHandlingServerCallListener<>(delegate, call, requestHeaders);
}
private class ExceptionHandlingServerCallListener<ReqT, RespT>
extends ForwardingServerCallListener.SimpleForwardingServerCallListener<ReqT> {
private ServerCall<ReqT, RespT> serverCall;
private Metadata metadata;
ExceptionHandlingServerCallListener(ServerCall.Listener<ReqT> listener, ServerCall<ReqT, RespT> serverCall,
Metadata metadata) {
super(listener);
this.serverCall = serverCall;
this.metadata = metadata;
}
@Override
public void onHalfClose() {
try {
super.onHalfClose();
} catch (RuntimeException ex) {
handleException(ex, serverCall, metadata);
throw ex;
}
}
@Override
public void onReady() {
try {
super.onReady();
} catch (RuntimeException ex) {
handleException(ex, serverCall, metadata);
throw ex;
}
}
private void handleException(RuntimeException exception, ServerCall<ReqT, RespT> serverCall, Metadata metadata) {
if (exception instanceof IllegalArgumentException) {
serverCall.close(Status.INVALID_ARGUMENT.withDescription(exception.getMessage()), metadata);
} else {
serverCall.close(Status.UNKNOWN, metadata);
}
}
}
}
再次运行client，可以看到抛出的异常内容已经变了
Exception in thread "main" io.grpc.StatusRuntimeException: INVALID_ARGUMENT: Missing name
这里只拦截了onReady和onHalfClose方法，因为拦截onCancel和onComplete方法对应返回内容已经没有任何作用
