在android上使用Socket.IO总是返回XHR轮询错误

Z时代
2024-01-10
分类：问答

我正在编写一个需要连接到在node.js服务器上运行的Socket.IO实例的android应用。

尝试使用iOS设备连接到实例并传输数据可以正常工作，但是当我尝试使用android设备进行操作时却失败了。

我正在使用Native java client，这是我在android端使用的代码：

mManager = new Manager(new URI("https://example.com"));
mSocket = mManager.socket("/users");
// socket events listeners
    mSocket.on(Socket.EVENT_CONNECTING, new Emitter.Listener() {
        @Override
        public void call(Object... args) {
            Log.v(TAG, "Caught EVENT_CONNECTING");
            for (Object obj : args) {
                Log.v(TAG, "Errors :: " + obj);
            }
        }
    }).on(Socket.EVENT_CONNECT, new Emitter.Listener() {
        @Override
        public void call(Object... args) {
            Log.v(TAG, "connected to the backend");
            Log.v(TAG, String.format("JSON Obj to emit: %s", jsonObject.toString()));
            mSocket.emit("hello_packet", jsonObject);
        }
    }).on(Socket.EVENT_RECONNECTING, new Emitter.Listener() {
        @Override
        public void call(Object... args) {
            Log.v(TAG, "Caught EVENT_RECONNECTING");
            for (Object obj : args) {
                Log.v(TAG, "Errors :: " + obj);
            }
        }
    }).on(Socket.EVENT_DISCONNECT, new Emitter.Listener() {
        @Override
        public void call(Object... args) {
            Log.v(TAG, "Socket disconnected");
        }
    }).on(Socket.EVENT_ERROR, new Emitter.Listener() {
        @Override
        public void call(Object... args) {
            Log.v(TAG, "Caught EVENT_ERROR");
            for (Object obj : args) {
                Log.v(TAG, "Errors :: " + obj);
            }
        }
    }).on(Socket.EVENT_CONNECT_ERROR, new Emitter.Listener() {
        @Override
        public void call(Object... args) {
            Log.v(TAG, "Caught EVENT_CONNECT_ERROR");
            for (Object obj : args) {
                Log.v(TAG, "Errors :: " + obj);
            }
        }
    });
    Log.v(TAG, "Connecting socket");
    mSocket.connect();

每当我尝试连接时（基本上是在line上mSocket.connect();），日志将显示以下行：

05-07 22:41:36.684 15552-15552/com.my.app V/Main Activity: Connecting socket 05-07 22:41:36.699 15552-15858/com.my.app V/Main Activity: Caught EVENT_CONNECTING 05-07 22:41:36.926 15552-15866/com.my.app V/Main Activity: Caught EVENT_CONNECT_ERROR 05-07 22:41:36.926 15552-15866/com.my.app V/Main Activity: Errors :: io.socket.engineio.client.EngineIOException: xhr poll error 05-07 22:41:38.189 15552-15884/com.my.app V/Main Activity: Caught EVENT_RECONNECTING 05-07 22:41:38.189 15552-15884/com.my.app V/Main Activity: Errors :: 1 05-07 22:41:38.207 15552-15887/com.my.app V/Main Activity: Caught EVENT_CONNECT_ERROR 05-07 22:41:38.208 15552-15887/com.my.app V/Main Activity: Errors :: io.socket.engineio.client.EngineIOException: xhr poll error 05-07 22:41:39.518 15552-15911/com.my.app V/Main Activity: Caught EVENT_RECONNECTING 05-07 22:41:39.518 15552-15911/com.my.app V/Main Activity: Errors :: 2 05-07 22:41:39.531 15552-15915/com.my.app V/Main Activity: Caught EVENT_CONNECT_ERROR 05-07 22:41:39.531 15552-15915/com.my.app V/Main Activity: Errors :: io.socket.engineio.client.EngineIOException: xhr poll error 05-07 22:41:41.846 15552-15949/com.my.app V/Main Activity: Caught EVENT_RECONNECTING 05-07 22:41:41.846 15552-15949/com.my.app V/Main Activity: Errors :: 3 05-07 22:41:41.857 15552-15953/com.my.app V/Main Activity: Caught EVENT_CONNECT_ERROR 05-07 22:41:41.857 15552-15953/com.my.app V/Main Activity: Errors :: io.socket.engineio.client.EngineIOException: xhr poll error 05-07 22:41:46.863 15552-16025/com.my.app V/Main Activity: Caught EVENT_RECONNECTING 05-07 22:41:46.864 15552-16025/com.my.app V/Main Activity: Errors :: 4 05-07 22:41:46.879 15552-16029/com.my.app V/Main Activity: Caught EVENT_CONNECT_ERROR 05-07 22:41:46.879 15552-16029/com.my.app V/Main Activity: Errors :: io.socket.engineio.client.EngineIOException: xhr poll error 05-07 22:41:51.883 15552-16126/com.my.app V/Main Activity: Caught EVENT_RECONNECTING 05-07 22:41:51.883 15552-16126/com.my.app V/Main Activity: Errors :: 5 05-07 22:41:51.895 15552-16130/com.my.app V/Main Activity: Caught EVENT_CONNECT_ERROR 05-07 22:41:51.895 15552-16130/com.my.app V/Main Activity: Errors :: io.socket.engineio.client.EngineIOException: xhr poll error 05-07 22:41:56.900 15552-16236/com.my.app V/Main Activity: Caught EVENT_RECONNECTING 05-07 22:41:56.900 15552-16236/com.my.app V/Main Activity: Errors :: 6 05-07 22:41:56.921 15552-16240/com.my.app V/Main Activity: Caught EVENT_CONNECT_ERROR 05-07 22:41:56.921 15552-16240/com.my.app V/Main Activity: Errors :: io.socket.engineio.client.EngineIOException: xhr poll error 05-07 22:42:01.927 15552-16357/com.my.app V/Main Activity: Caught EVENT_RECONNECTING 05-07 22:42:01.927 15552-16357/com.my.app V/Main Activity: Errors :: 7 05-07 22:42:01.945 15552-16361/com.my.app V/Main Activity: Caught EVENT_CONNECT_ERROR 05-07 22:42:01.945 15552-16361/com.my.app V/Main Activity: Errors :: io.socket.engineio.client.EngineIOException: xhr poll error 05-07 22:42:06.951 15552-16466/com.my.app V/Main Activity: Caught EVENT_RECONNECTING 05-07 22:42:06.952 15552-16466/com.my.app V/Main Activity: Errors :: 8 05-07 22:42:06.969 15552-16470/com.my.app V/Main Activity: Caught EVENT_CONNECT_ERROR 05-07 22:42:06.970 15552-16470/com.my.app V/Main Activity: Errors :: io.socket.engineio.client.EngineIOException: xhr poll error 05-07 22:42:11.975 15552-16545/com.my.app V/Main Activity: Caught EVENT_RECONNECTING 05-07 22:42:11.976 15552-16545/com.my.app V/Main Activity: Errors :: 9 05-07 22:42:11.994 15552-16549/com.my.app V/Main Activity: Caught EVENT_CONNECT_ERROR 05-07 22:42:11.994 15552-16549/com.my.app V/Main Activity: Errors :: io.socket.engineio.client.EngineIOException: xhr poll error 05-07 22:42:17.000 15552-16629/com.my.app V/Main Activity: Caught EVENT_RECONNECTING 05-07 22:42:17.000 15552-16629/com.my.app V/Main Activity: Errors :: 10 05-07 22:42:17.012 15552-16633/com.my.app V/Main Activity: Caught EVENT_CONNECT_ERROR 05-07 22:42:17.012 15552-16633/com.my.app V/Main Activity: Errors :: io.socket.engineio.client.EngineIOException: xhr poll error 05-07 22:42:22.017 15552-16710/com.my.app V/Main Activity: Caught EVENT_RECONNECTING 05-07 22:42:22.017 15552-16710/com.my.app V/Main Activity: Errors :: 11 05-07 22:42:22.033 15552-16714/com.my.app V/Main Activity: Caught EVENT_CONNECT_ERROR 05-07 22:42:22.033 15552-16714/com.my.app V/Main Activity: Errors :: io.socket.engineio.client.EngineIOException: xhr poll error 05-07 22:42:27.039 15552-16788/com.my.app V/Main Activity: Caught EVENT_RECONNECTING 05-07 22:42:27.039 15552-16788/com.my.app V/Main Activity: Errors :: 12 05-07 22:42:27.056 15552-16792/com.my.app V/Main Activity: Caught EVENT_CONNECT_ERROR 05-07 22:42:27.056 15552-16792/com.my.app V/Main Activity: Errors :: io.socket.engineio.client.EngineIOException: xhr poll error 05-07 22:42:32.061 15552-16957/com.my.app V/Main Activity: Caught EVENT_RECONNECTING 05-07 22:42:32.062 15552-16957/com.my.app V/Main Activity: Errors :: 13

因此，尝试连接后我立即收到xhr poll错误，并且随后的所有连接尝试均达到相同的结果。

我看到一些帖子说这样的问题可能是由SSL证书问题引起的，尽管我对Socket.IO库使用的SSL上下文进行的任何尝试都无效。

如果anyoen有一个想法，我可能可以尝试使它起作用，那就太好了。

如果缺少任何信息或代码样本，请告诉我，我将其添加。

回答：

经过进一步测试，我发现以下内容：

如果在遇到其他事件（例如EVENT_ERROR）时调试套接字，则捕获的异常将包含从您尝试访问的地址收到的响应代码。

就我而言，当尝试使用HTTP到达服务器时，我收到了301响应代码，因为尝试访问的URL自动将我重定向到HTTPS地址。

尝试访问HTTPS地址时，我收到了401响应代码-表示我的套接字发出的请求已到达服务器，但未获得授权-原因是目标服务器已而我没有提供套接字请求标头中的必需凭据。

提供所需的标头后，我设法正确连接到套接字服务器，但是在发送请求时失败，并且我的套接字返回到重新连接尝试循环-原因是我从服务器发送给服务器的JSON我的Android手机格式不符合预期，服务器无法收到该请求。

我用来向套接字请求添加基本身份验证标头的代码：

// Adding authentication headers when encountering EVENT_TRANSPORT
mSocket.io().on(Manager.EVENT_TRANSPORT, new Emitter.Listener() {
    @Override
    public void call(Object... args) {
        Transport transport = (Transport) args[0];
        // Adding headers when EVENT_REQUEST_HEADERS is called
        transport.on(Transport.EVENT_REQUEST_HEADERS, new Emitter.Listener() {
            @Override
            public void call(Object... args) {
                Log.v(TAG, "Caught EVENT_REQUEST_HEADERS after EVENT_TRANSPORT, adding headers");
                Map<String, List<String>> mHeaders = (Map<String, List<String>>)args[0];
                mHeaders.put("Authorization", Arrays.asList("Basic bXl1c2VyOm15cGFzczEyMw=="));
            }
        });
    }
});