c# - 如何在 Android 中使用信号器

Question

我正在尝试将 signalR 集成到 android 应用程序中，但没有成功。我一直在查看各种链接，但没有一个提供有关实现的正确信息。

我有以下问题。

• SignalR 集成必须在 Service/Intent Service 中完成？
• 如果我们想通过相同的调用方法接收响应，那么如何获取？

我添加了三个库，即 signalr android、signalr client 和 gson 但无法理解代码的工作原理，没有适当的文档可用于理解代码。

问了一些问题，但信息不多

SignalR in Android Studio Unable to implement p2p chat using SignalR in Android

如果有人在 native 应用程序的信号方面有经验，那对我很有帮助。

更新

    public class SignalRService extends Service {


    private static final String TAG = "Service";
    private HubConnection mHubConnection;
    private HubProxy mHubProxy;
    private Handler mHandler; // to display Toast message
    private final IBinder mBinder = new LocalBinder(); 

    private SharedPreferences sp;

    @Override
    public void onCreate() {
        super.onCreate();

        Utility.showLog(TAG, "Service Created");

        sp = getSharedPreferences(Utility.SHARED_PREFS, MODE_PRIVATE);
        mHandler = new Handler(Looper.myLooper());
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {

        int result = super.onStartCommand(intent, flags, startId);
        startSignalR();
        return result;
    }

    @Override
    public IBinder onBind(Intent intent) {

        startSignalR();
        return mBinder;
    }

    /**
     * Class used for the client Binder.  Because we know this service always
     * runs in the same process as its clients, we don't need to deal with IPC.
     */
    public class LocalBinder extends Binder {
        public SignalRService getService() {
            // Return this instance of SignalRService so clients can call public methods
            return SignalRService.this;
        }
    }

    /**
     * method for clients (activities)
     */
    public void sendMessage() {

        String SERVER_METHOD_SEND = "iAmAvailable";
        final String string = new String();

        mHubProxy.invoke(new String(), SERVER_METHOD_SEND, sp.getString("user_id", null), sp.getString("pass", null), "TransMedic").done(new Action() {
            @Override
            public void run(Object o) throws Exception {

                Utility.showLog(TAG, o.toString());

            }


        }).onError(new ErrorCallback() {
            @Override
            public void onError(Throwable throwable) {

            }
        });
    }

    private void startSignalR() {

        Platform.loadPlatformComponent(new AndroidPlatformComponent());

        String serverUrl = "http://transit.alwaysaware.org/signalr";

        mHubConnection = new HubConnection(serverUrl);

        String SERVER_HUB_CHAT = "ChatHub";

        mHubProxy = mHubConnection.createHubProxy(SERVER_HUB_CHAT);

        ClientTransport clientTransport = new ServerSentEventsTransport(mHubConnection.getLogger());

        SignalRFuture<Void> signalRFuture = mHubConnection.start(clientTransport);


        try {

            signalRFuture.get();

        } catch (InterruptedException | ExecutionException e) {

            e.printStackTrace();
            return;

        }

        sendMessage();
    }

    @Override
    public void onDestroy() {

        mHubConnection.stop();
        super.onDestroy();

    }
}

Answer 1

2018 年更新:

如果您使用的是 SignalR.net Core，请使用 this library否则会出现连接错误。

服务器端:

以下是我的示例服务器端代码，可以关注public void Send(string message)和public void SendChatMessage(string to, string message) .

• Server-side app: public void SendChatMessage(string to, string message)

  • Android client app: mHubProxy.invoke("SendChatMessage", receiverName, message);

• Server-side app: public void Send(string message)

  • Android client app: mHubProxy.invoke("Send", message);

namespace SignalRDemo
{
    public class ChatHub : Hub
    {
        private static ConcurrentDictionary<string, string> FromUsers = new ConcurrentDictionary<string, string>();         // <connectionId, userName>
        private static ConcurrentDictionary<string, string> ToUsers = new ConcurrentDictionary<string, string>();           // <userName, connectionId>
        private string userName = "";

    public override Task OnConnected()
    {
        DoConnect();
        Clients.AllExcept(Context.ConnectionId).broadcastMessage(new ChatMessage() { UserName = userName, Message = "I'm Online" });
        return base.OnConnected();
    }

    public override Task OnDisconnected(bool stopCalled)
    {
        if (stopCalled) // Client explicitly closed the connection
        {
            string id = Context.ConnectionId;
            FromUsers.TryRemove(id, out userName);
            ToUsers.TryRemove(userName, out id);
            Clients.AllExcept(Context.ConnectionId).broadcastMessage(new ChatMessage() { UserName = userName, Message = "I'm Offline" });
        }
        else // Client timed out
        {
            // Do nothing here...
            // FromUsers.TryGetValue(Context.ConnectionId, out userName);            
            // Clients.AllExcept(Context.ConnectionId).broadcastMessage(new ChatMessage() { UserName = userName, Message = "I'm Offline By TimeOut"});                
        }

        return base.OnDisconnected(stopCalled);
    }

    public override Task OnReconnected()
    {
        DoConnect();
        Clients.AllExcept(Context.ConnectionId).broadcastMessage(new ChatMessage() { UserName = userName, Message = "I'm Online Again" });
        return base.OnReconnected();
    }

    private void DoConnect()
    {
        userName = Context.Request.Headers["User-Name"];
        if (userName == null || userName.Length == 0)
        {
            userName = Context.QueryString["User-Name"]; // for javascript clients
        }
        FromUsers.TryAdd(Context.ConnectionId, userName);
        String oldId; // for case: disconnected from Client
        ToUsers.TryRemove(userName, out oldId);
        ToUsers.TryAdd(userName, Context.ConnectionId);
    }

    public void Send(string message)
    {
        // Call the broadcastMessage method to update clients.            
        string fromUser;
        FromUsers.TryGetValue(Context.ConnectionId, out fromUser);
        Clients.AllExcept(Context.ConnectionId).broadcastMessage(new ChatMessage() { UserName = fromUser, Message = message });
    }

    public void SendChatMessage(string to, string message)
    {
        FromUsers.TryGetValue(Context.ConnectionId, out userName);
        string receiver_ConnectionId;
        ToUsers.TryGetValue(to, out receiver_ConnectionId);

        if (receiver_ConnectionId != null && receiver_ConnectionId.Length > 0)
        {
            Clients.Client(receiver_ConnectionId).broadcastMessage(new ChatMessage() { UserName = userName, Message = message });
        }
    }        
}

public class ChatMessage
{
    public string UserName { get; set; }
    public string Message { get; set; }
}
}

客户端:

如果您还没有阅读我对以下问题的回答:

SignalR integration in android studio

然后，这是我的工作基本代码:

public class SignalRService extends Service {
    private HubConnection mHubConnection;
    private HubProxy mHubProxy;
    private Handler mHandler; // to display Toast message
    private final IBinder mBinder = new LocalBinder(); // Binder given to clients

public SignalRService() {
}

@Override
public void onCreate() {
    super.onCreate();
    mHandler = new Handler(Looper.getMainLooper());
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    int result = super.onStartCommand(intent, flags, startId);
    startSignalR();
    return result;
}

@Override
public void onDestroy() {
    mHubConnection.stop();
    super.onDestroy();
}

@Override
public IBinder onBind(Intent intent) {
    // Return the communication channel to the service.
    startSignalR();
    return mBinder;
}

/**
 * Class used for the client Binder.  Because we know this service always
 * runs in the same process as its clients, we don't need to deal with IPC.
 */
public class LocalBinder extends Binder {
    public SignalRService getService() {
        // Return this instance of SignalRService so clients can call public methods
        return SignalRService.this;
    }
}

/**
 * method for clients (activities)
 */
public void sendMessage(String message) {
    String SERVER_METHOD_SEND = "Send";
    mHubProxy.invoke(SERVER_METHOD_SEND, message);
}    

private void startSignalR() {
    Platform.loadPlatformComponent(new AndroidPlatformComponent());

    Credentials credentials = new Credentials() {
        @Override
        public void prepareRequest(Request request) {
            request.addHeader("User-Name", "BNK");
        }
    };

    String serverUrl = "http://192.168.1.100";
    mHubConnection = new HubConnection(serverUrl);
    mHubConnection.setCredentials(credentials);
    String SERVER_HUB_CHAT = "ChatHub";
    mHubProxy = mHubConnection.createHubProxy(SERVER_HUB_CHAT);
    ClientTransport clientTransport = new ServerSentEventsTransport(mHubConnection.getLogger());
    SignalRFuture<Void> signalRFuture = mHubConnection.start(clientTransport);

    try {
        signalRFuture.get();
    } catch (InterruptedException | ExecutionException e) {
        e.printStackTrace();
        return;
    }

    String HELLO_MSG = "Hello from Android!";
    sendMessage(HELLO_MSG);

    String CLIENT_METHOD_BROADAST_MESSAGE = "broadcastMessage";
    mHubProxy.on(CLIENT_METHOD_BROADAST_MESSAGE,
            new SubscriptionHandler1<CustomMessage>() {
                @Override
                public void run(final CustomMessage msg) {
                    final String finalMsg = msg.UserName + " says " + msg.Message;
                    // display Toast message
                    mHandler.post(new Runnable() {
                        @Override
                        public void run() {
                            Toast.makeText(getApplicationContext(), finalMsg, Toast.LENGTH_SHORT).show();
                        }
                    });
                }
            }
            , CustomMessage.class);
}
}

Activity :

public class MainActivity extends AppCompatActivity {

private final Context mContext = this;
private SignalRService mService;
private boolean mBound = false;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    Intent intent = new Intent();
    intent.setClass(mContext, SignalRService.class);
    bindService(intent, mConnection, Context.BIND_AUTO_CREATE);
}

@Override
protected void onStop() {
    // Unbind from the service
    if (mBound) {
        unbindService(mConnection);
        mBound = false;
    }
    super.onStop();
}    

public void sendMessage(View view) {
    if (mBound) {
        // Call a method from the SignalRService.
        // However, if this call were something that might hang, then this request should
        // occur in a separate thread to avoid slowing down the activity performance.
        EditText editText = (EditText) findViewById(R.id.edit_message);            
        if (editText != null && editText.getText().length() > 0) {                
            String message = editText.getText().toString();
            mService.sendMessage(message);
        }
    }
}

/**
 * Defines callbacks for service binding, passed to bindService()
 */
private final ServiceConnection mConnection = new ServiceConnection() {

    @Override
    public void onServiceConnected(ComponentName className,
                                   IBinder service) {
        // We've bound to SignalRService, cast the IBinder and get SignalRService instance
        SignalRService.LocalBinder binder = (SignalRService.LocalBinder) service;
        mService = binder.getService();
        mBound = true;
    }

    @Override
    public void onServiceDisconnected(ComponentName arg0) {
        mBound = false;
    }
};
}

CustomMessage 类:

public class CustomMessage {
    public String UserName;
    public String Message;
}

您还可以在 this GitHub link 上查看我的示例客户端项目

---

INVOKE 响应更新:

我刚刚添加了新的示例方法:

服务器端:

public string iAmAvailable(string username, string password, string message)
{            
     return "BNK Response for testing Android INVOKE";
}

客户端:

mHubProxy.invoke(String.class, "iAmAvailable", "username", "password", "TransMedic").done(new Action<String>() {
            @Override
            public void run(String s) throws Exception {
                Log.w("SimpleSignalR", s);
            }
        }).onError(new ErrorCallback() {
            @Override
            public void onError(Throwable throwable) {
                Log.e("SimpleSignalR", throwable.toString());
            }
        });

这是截图: