Thanks for the reply. I try ServerCallStreamObserver and Context
<http://www.grpc.io/grpc-java/javadoc/io/grpc/Context.html#addListener-io.grpc.Context.CancellationListener-java.util.concurrent.Executor->,
and find out that they solve half of my problem: to get a callback when
cancellation.
Then the other half is just I was confused by myself.
So I just list all the staff here in case someone may need
public StreamObserver<Message> chat(StreamObserver<Message> responseObserver){
final UserData data = new UserData();
final ServerCallStreamObserver<Message> rsob =
(ServerCallStreamObserver<Message>) responseObserver;
rsob.setOnCancelHandler(new Runnable() {
@Override
public void run() {
System.out.println("OnCancelHandler:" + data.name);//
}
});
return new StreamObserver<Message>() {
@Override
public void onNext(Message value) {
data.name = value.getFrom();
}
UserData is a POJO.
chat() will be call when client begin RPC, so just create UserData there and
use it in onError and other callbacks.
在 2017年4月26日星期三 UTC+8上午12:39:51，Eric Anderson写道：
>
> On Tue, Apr 25, 2017 at 7:04 AM, 黄骐 <sky7...@gmail.com <javascript:>>
> wrote:
>
>> When client make the first connect, I save the responseStreamObserver
>> and link it with the client's user ID,
>> so the server can use the StreamObserver when needs to push message to
>> client.
>>
>
> That sounds good.
>
> But now I can not find a way to identify the client when connection is
>> lost and "CANNCELED" is catched in onError on server side.
>>
>
> If the client has already completed its side of the stream, then onError
> won't be called, because it can only be called once. Instead, You can call
> ServerCallStreamObserver.setOnCancelHandler(Runnable)
> <http://www.grpc.io/grpc-java/javadoc/io/grpc/stub/ServerCallStreamObserver.html#setOnCancelHandler-java.lang.Runnable->
> and
> the Runnable will be executed if the client disconnects. To get the
> ServerCallStreamObserver, simply cast the request StreamObserver.
>
> An alternative is to use Context.addListener(CancellationListener,
> Executor)
> <http://www.grpc.io/grpc-java/javadoc/io/grpc/Context.html#addListener-io.grpc.Context.CancellationListener-java.util.concurrent.Executor->
> as
> the Context is also cancelled when the RPC is cancelled (all I/O failures
> on server-side act like cancellation in the API).
>
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