Android

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PC端的XX助手和手机App的通讯原理:

# 把PC端8000端口的数据, 转发到Android端的9000端口上.adb forward tcp:8000 tcp:9000

什么是转发?

执行命令后, PC端的8000端口会被 adb
监听, 这个时候我们只需要往8000端口写数据, 这个数据就会发送到手机端的9000端口上.

PC端程序

把输入内容发送给8000端口

public class PCClient {    public static void main(String[] args) throws IOException {        System.out.println("任意字符, 回车键发送Toast");        Scanner scanner = new Scanner(System.in);        while (true) {            String msg = scanner.next();            sendToast(msg);        }    }    public static void sendToast(String msg) throws IOException {        Socket socket = new Socket("127.0.0.1", 8000);        DataInputStream dis = new DataInputStream(socket.getInputStream());        DataOutputStream dos = new DataOutputStream(socket.getOutputStream());        dos.writeUTF(msg);        socket.close();    }}

Android端程序

监听9000端口, 把收到的数据, Toast在屏幕上

public class MainActivity extends AppCompatActivity {    private static final String TAG = "ServerThread";    ServerThread serverThread;    Handler handler = new Handler() {        @Override        public void handleMessage(Message msg) {            Toast.makeText(getApplicationContext(), msg.getData().getString("MSG", "Toast"), Toast.LENGTH_SHORT).show();        }    };    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        serverThread = new ServerThread();        serverThread.start();    }    @Override    protected void onDestroy() {        super.onDestroy();        serverThread.setIsLoop(false);    }    class ServerThread extends Thread {        boolean isLoop = true;        public void setIsLoop(boolean isLoop) {            this.isLoop = isLoop;        }        @Override        public void run() {            Log.d(TAG, "running");            ServerSocket serverSocket = null;            try {                serverSocket = new ServerSocket(9000);                while (isLoop) {                    Socket socket = serverSocket.accept();                    Log.d(TAG, "accept");                    DataInputStream inputStream = new DataInputStream(socket.getInputStream());                    DataOutputStream outputStream = new DataOutputStream(socket.getOutputStream());                    String msg = inputStream.readUTF();                    Message message = Message.obtain();                    Bundle bundle = new Bundle();                    bundle.putString("MSG", msg);                    message.setData(bundle);                    handler.sendMessage(message);                    socket.close();                }            } catch (Exception e) {                e.printStackTrace();            } finally {                Log.d(TAG, "destory");                if (serverSocket != null) {                    try {                        serverSocket.close();                    } catch (Exception e) {                        e.printStackTrace();                    }                }            }        }    }}

运行效果

Paste_Image.png

源码

Android-Pc-Socket-Connection

实际开发中的问题

Android端的程序有可能被干掉
adb forward 有可能会被干掉

由于连接不稳定性，判断真正连接成功的方法，只有轮询收发握手数据包：
C发送一个数据包，等待S回复；
C如果收到了S的回复包，说明连通。
如果接收超时，则认为没有连通.
在没有连通的情况下，需要重新建立Socket，并Connect()，然后再尝试握手。

3. java.io.EOFException

需要在把close注释掉.........................与真正的socket还有有区别的，每次创建连接重新open

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