使用Socket處理跨進程的實時聊天

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Socket是套接字, 網絡通信經常使用的方法, 分爲TCP和UDP兩種模式, 需要網絡權限, 當然也可以應用於跨進程通信. 本文通過一個簡易的Android聊天程序, 熟悉Socket的使用方法.

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邏輯: 客戶端向服務端發送數據, 服務端收到後返回客戶端數據.

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Server

Socket處理屬於網絡請求, 需要在其他線程中使用, 不能應用於主線程.

new Thread(new TcpServer()).start();

TCP服務的Socket鏈接. 設置Socket的端口號ServerSocket(PORT), 不斷循環的接收數據serverSocket.accept(), 在responseClient()方法處理數據.

private class TcpServer implements Runnable {
    @Override public void run() {
        ServerSocket serverSocket = null;
        try {
            serverSocket = new ServerSocket(PORT);
        } catch (IOException e) {
            Log.e(TAG, "建立鏈接失敗, 端口:" + PORT);
            e.printStackTrace();
            return; // 鏈接建立失敗直接返回
        }

        while (!mIsServiceDestroyed) {
            try {
                final Socket client = serverSocket.accept();
                Log.e(TAG, "接收數據");
                new Thread() {
                    @Override public void run() {
                        try {
                            responseClient(client);
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }.start();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

mIsServiceDestroyed用於判斷服務器是否存活, 防止內存泄露.

處理Socket數據, 使用BufferedReader讀取數據, 使用PrintWriter寫入數據, 循環檢測, 結束時關閉緩存和Socket.

private void responseClient(Socket client) throws IOException {
    // 接收客戶端消息
    BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream()));

    // 向客戶端發送消息
    PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(client.getOutputStream())), true);
    out.println("歡迎歡迎, 我是Spike!");
    while (!mIsServiceDestroyed) {
        String str = in.readLine();
        Log.e(TAG, "信息來自: " + str);
        if (str == null) {
            break;
        }

        int i = new Random().nextInt(mDefinedMessages.length);
        String msg = mDefinedMessages[i];
        out.println(msg);
        Log.e(TAG, "發送信息: " + msg);
    }

    System.out.println("客戶端退出");

    // 關閉通信
    close(out);
    close(in);
    client.close();
}

服務器使用單獨線程, 模擬跨進程通信.

<service
    android:name=".TCPServerService"
    android:process=":remote"/>

需要申請網絡權限, 連網和訪問網絡狀態.

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>

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Client

客戶端, 向服務器發送數據, 並接收服務器返回的數據.

啓動服務, 連接TCP服務器.

Intent intent = new Intent(this, TCPServerService.class);
startService(intent);

new Thread(new Runnable() {
    @Override public void run() {
        connectTCPServer();
    }
}).start();

嘗試連接服務器, 每隔1秒進行重試, 並初始化發送緩存PrintWriter.

Socket socket = null;

// 不停重試直到連接成功爲止
while (socket == null) {
    try {
        socket = new Socket("localhost", TCPServerService.PORT);
        mClientSocket = socket;
        mPrintWriter = new PrintWriter(new BufferedWriter(
                new OutputStreamWriter(socket.getOutputStream())), true);
        mHandler.sendEmptyMessage(MESSAGE_SOCKET_CONNECTED);
        Log.e(TAG, "服務器連接成功");
    } catch (IOException e) {
        SystemClock.sleep(1000);
        Log.e(TAG, "連接TCP服務失敗, 重試...");
    }
}

成功後, 循環調用, 監聽BufferedReader, 是否有數據返回.

BufferedReader br = new BufferedReader(
        new InputStreamReader(socket.getInputStream()));
while (!MainActivity.this.isFinishing()) {
    String msg = br.readLine();
    Log.e(TAG, "收到信息: " + msg);
    if (msg != null) {
        String time = new SimpleDateFormat("HH:mm:ss", Locale.ENGLISH).format(System.currentTimeMillis());
        String showedMsg = "server " + time + ":" + msg + "\n";
        mHandler.obtainMessage(MESSAGE_RECEIVE_NEW_MSG, showedMsg)
                .sendToTarget();
    }
}

Handler處理數據, 分爲連接成功和獲取數據兩種情況.

private Handler mHandler = new Handler() {
    @Override public void handleMessage(Message msg) {
        switch (msg.what) {
            case MESSAGE_RECEIVE_NEW_MSG:
                mTvContent.setText(
                        String.valueOf(mTvContent.getText().toString() + msg.obj));
                break;
            case MESSAGE_SOCKET_CONNECTED:
                mBSend.setEnabled(true);
                break;
            default:
                break;
        }
    }
};

點擊按鈕發送數據, 直接在PrintWriter中寫入, 即可.

public void sendMessage(View view) {
    String msg = mEtMessage.getText().toString();
    if (!TextUtils.isEmpty(msg) && mPrintWriter != null) {
        mPrintWriter.println(msg);
        mEtMessage.setText("");
        String time = new SimpleDateFormat("HH:mm:ss", Locale.ENGLISH).format(System.currentTimeMillis());
        String showedMsg = "self " + time + ":" + msg + "\n";
        mTvContent.setText(String.valueOf(mTvContent.getText() + showedMsg));
    }
}

當我們向服務端發送數據時, 就會獲取服務端的返回, 模擬聊天效果.

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效果

Socket作爲經典的網絡通信方式, 有很多應用, 也可以實現跨進程通信, 希望能熟練掌握.

OK, that’s all! Enjoy it!