Android WebSocket 方案选型OkHttp

目前Android WebSocket 框架 主要包括:

• SocketIO
• Java-WebSocket
• OkHttp WebSocket

一开始我首选的是采用SocketIO方案，因为考虑该方案封装接口好，提供异步回调机制，但和后端同事沟通发现目前客户端的SocketIO不支持ws wss协议, 所以无奈只能放弃。

接着考虑采用Java-WebSocket方案，该方案是websocket的java完整实现，目前github6.5K星，于是考虑导入，但是在实测时发现调用connect，reConnect，如果导致线程异常报错，网上搜索相关解决方案，并不能有效解决此问题，当然也可能是我没有更深入分析此问题。

最后考虑采用OkHttp方案，基于OkHttp优秀的线程读写控制机制，发现该方案出奇的稳定。

参考文档：https://square.github.io/okhttp/4.x/okhttp/okhttp3/-web-socket/
以下是对OkHttp websocket的简单封装

public class WebSocketHandler extends WebSocketListener {
    private static final String TAG = "WebSocketHandler ";

    private String wsUrl;

    private WebSocket webSocket;

    private ConnectStatus status;

    private OkHttpClient client = new OkHttpClient.Builder()
            .build();

    private WebSocketHandler(String wsUrl) {
        this.wsUrl = wsUrl;
    }

    private static WebSocketHandler INST;

    public static WebSocketHandler getInstance(String url) {
        if (INST == null) {
            synchronized (WebSocketHandler.class) {
                INST = new WebSocketHandler(url);
            }
        }

        return INST;
    }

    public ConnectStatus getStatus() {
        return status;
    }

    public void connect() {
        //构造request对象
        Request request = new Request.Builder()
                .url(wsUrl)
                .build();

        webSocket = client.newWebSocket(request, this);
        status = ConnectStatus.Connecting;
    }

    public void reConnect() {
        if (webSocket != null) {
            webSocket = client.newWebSocket(webSocket.request(), this);
        }
    }

    public void send(String text) {
        if (webSocket != null) {
            log("send： " + text);
            webSocket.send(text);
        }
    }

    public void cancel() {
        if (webSocket != null) {
            webSocket.cancel();
        }
    }

    public void close() {
        if (webSocket != null) {
            webSocket.close(1000, null);
        }
    }

    @Override
    public void onOpen(WebSocket webSocket, Response response) {
        super.onOpen(webSocket, response);
        log("onOpen");
        this.status = ConnectStatus.Open;
        if (mSocketIOCallBack != null) {
            mSocketIOCallBack.onOpen();
        }
    }

    @Override
    public void onMessage(WebSocket webSocket, String text) {
        super.onMessage(webSocket, text);
        log("onMessage: " + text);
        if (mSocketIOCallBack != null) {
            mSocketIOCallBack.onMessage(text);
        }
    }

    @Override
    public void onMessage(WebSocket webSocket, ByteString bytes) {
        super.onMessage(webSocket, bytes);
    }

    @Override
    public void onClosing(WebSocket webSocket, int code, String reason) {
        super.onClosing(webSocket, code, reason);
        this.status = ConnectStatus.Closing;
        log("onClosing");
    }

    @Override
    public void onClosed(WebSocket webSocket, int code, String reason) {
        super.onClosed(webSocket, code, reason);
        log("onClosed");
        this.status = ConnectStatus.Closed;
        if (mSocketIOCallBack != null) {
            mSocketIOCallBack.onClose();
        }
    }

    @Override
    public void onFailure(WebSocket webSocket, Throwable t, @Nullable Response response) {
        super.onFailure(webSocket, t, response);
        log("onFailure: " + t.toString());
        t.printStackTrace();
        this.status = ConnectStatus.Canceled;
        if (mSocketIOCallBack != null) {
            mSocketIOCallBack.onConnectError(t);
        }
    }


    private WebSocketCallBack mSocketIOCallBack;

    public void setSocketIOCallBack(WebSocketCallBack callBack) {
        mSocketIOCallBack = callBack;
    }

    public void removeSocketIOCallBack() {
        mSocketIOCallBack = null;
    }
}

public enum ConnectStatus {
    Connecting, // the initial state of each web socket.
    Open, // the web socket has been accepted by the remote peer
    Closing, // one of the peers on the web socket has initiated a graceful shutdown
    Closed, //  the web socket has transmitted all of its messages and has received all messages from the peer
    Canceled // the web socket connection failed
}