Question

我想通过USB线将Android设备与Windows笔记本电脑连接为客户端 - 服务器桥接器。我用Java编写了我的客户端代码。当我的设备连接到我的WiFi调制解调器并且我的笔记本电脑也通过LAN电缆连接时，我将应用程序桌面上的android设备IP设置为连接到服务器套接字的地址。但是，当我的WiFi调制解调器关闭，我想用USB线连接Android设备和笔记本电脑。我的设备的IP地址不可用，我无法连接到Android设备。

另一个问题：我可以通过USB线连接到服务器并使用IP地址打开套接字。

Android代码

public class ActivityMain extends AppCompatActivity {
private Button button ;
public static final int TIMEOUT = 10;
private String connectionStatus = null;
private Handler mHandler = null;
private ServerSocket serverSocket = null;
private Socket socket = null;
private ObjectOutputStream  objectOutputStream;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = (Button) findViewById(R.id.button);

configure_button();
 }

  @Override
  public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    switch (requestCode) {
      case 10:
        configure_button();
        break;
      default:
        break;
    }
  }
  void configure_button() {
    // first check for permissions
    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
      ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
      ActivityCompat.checkSelfPermission(this, Manifest.permission.INTERNET)               != PackageManager.PERMISSION_GRANTED) {

      if  (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)  {
        requestPermissions(new String[] {Manifest.permission.ACCESS_FINE_LOCATION, Manifest.permission.ACCESS_COARSE_LOCATION, Manifest.permission.INTERNET}, 10);
      }
      return;
    }
    //this code won't execute if permissions are not allower, because in the line above there is return statement.
    button.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View view) {
        //initialize serverSocket socket in a new separate thread
        new Thread(initializeConnection).start();
        String msg = "Attempting to connect";
        Toast.makeText(ActivityMain.this, msg, Toast.LENGTH_SHORT).show();
      }
    });
  }

  //threads
  private final Runnable initializeConnection = new Thread(){
@Override
public void run() {
  // initialize server socket
  try {
    serverSocket = new ServerSocket(38300);
    serverSocket.setSoTimeout(ActivityMain.TIMEOUT * 1000);

    //attempt to accept a connection
    socket = serverSocket.accept();

    objectOutputStream = new ObjectOutputStream(socket.getOutputStream());
    try {
      while(true) {
        for (int i = 0; i < 1000; i++) {
          //objectOutputStream.reset();
          objectOutputStream.writeObject("number" + i);
          // objectOutputStream.writeBytes("number"+i);
          System.out.println("send>" + "number" + i);
        }
      }
    } catch (IOException ioException) {
      //Log.e(ActivityMain.TAG, "" + ioException);
    }
  } catch (SocketTimeoutException e) {
    connectionStatus = "Connection has timed objectOutputStream! Please try again";
    // mHandler.post(showConnectionStatus);
  }
  catch(IOException e)
  {
    //Log.e(ActivityMain.TAG, ""+e);
  }

  if(socket != null)
  {
    connectionStatus = "Connection was succesful";
    // mHandler.post(showConnectionStatus);
  }
}
};
}

客户代码

public class CCC {  
    public static void main(String[] args)
    {
        System.out.println("hi");
        Socket echoSocket = null;
        ObjectOutputStream out = null;
        ObjectInputStream in = null;
        String message = "";

        // Create socket connection with host address as localhost and port number with 38300 
        try
        {
            echoSocket = new Socket("192.168.1.19", 38300);

            in = new ObjectInputStream(echoSocket.getInputStream());

            // Communicating with the server
            try
            {
                while(true){
                message = (String) in.readObject();
                System.out.println("server>" + message);

                }
            }
            catch (ClassNotFoundException classNot)
            {
                System.err.println("data received in unknown format");
            }
        }
        catch (UnknownHostException e)
        {
            System.err.println("Don't know about host: LocalHost.");
            System.exit(1);
        }
        catch (IOException e)
        {
            System.err.println("Couldn't get I/O for " + "the connection to: LocalHost:");
            System.exit(1);
        }
        finally
        {
            // Closing connection
            try
            {
                in.close();

                if (echoSocket != null)
                {
                    echoSocket.close();
                }
            }
            catch (IOException ioException)
            {
                ioException.printStackTrace();
            }
        }
    }
}

我需要每隔一秒从服务器发送位置数据到客户端;

Answer 1

在客户端代码中，您正在使用while(true)无限地读取ObjectInputStream。如果到达文件末尾，则不会超出循环范围。

程序无法再读取，因为它已到达文件的末尾，因此可能会抛出EOFException。使用if(in.readObject() != null)进行检查。你应该抓住异常并自然地处理它。

try {
    while(true) {
        message = in.readObject(); 
        System.out.println("server>" + message);
    }
} catch (EOFException e) { 
    // handle exception
    System.out.println("Reached end of file while reading.");
}

EOFException可帮助您摆脱循环。

Answer 2

我终于找到了答案。用于通信PC到Android设备的客户端 - 服务器表单。你应该使用ADB.you你应该去你的电脑中的女巫cmd到adb的地方并输入＆gt; adb forward tcp：38300（端口号例如38300）tcp：38300 使用此命令后，应关闭IDE并使用＆＃34; localhost＆＃34;而不是像这样的Android设备IP-＆gt; echoSocket = new Socket（＆＃34; localhost＆＃34;，38300）; 已经完成了。

将PC连接到Android设备以通过USB电缆形成客户端 - 服务器链接

2 个答案: