在没有公网/wifi的情况下让 Android 手机通过 USB 或者让虚拟机里的 Android 系统与电脑进行通信。

基本原理是当 Android 手机通过 USB 连接电脑时，两者之间就形成了一个局域网（具体是由 ADB 实现的）。 嗯，看到这里只要了解网络编程的同学就知道怎么做了。 就是把 Android 手机作为服务器，监听某个端口来获取客户端连接,而 PC 可以作为客户端。 这里的问题是客户端要怎么连接到服务器的端口，这个需要运行 adb shell 指令 ：

adb.exe forward tcp:[port1] tcp:[port2]  // port1: PC 上的端口; port2: Android 上的端口。此处会把 PC 上发往 port1 的信息转发至 Android 的 port2

Android 服务器代码：

void startServer() {
    ServerSocket serverSocket = null;

    try {
        Log.e("Android", "start to accpet");

        serverSocket = new ServerSocket(SERVER_PORT); // 即 port2

        while (true) {
            Socket client = serverSocket.accept();

            Log.e("Android", "receive client");

            try {
                BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream()));
                final String str = in.readLine();

                Log.e("Android", str);

                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        show.setText(str);
                    }
                });

                PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(client.getOutputStream())),true);
                out.println("I'm Android");
                in.close();
                out.close();
            } catch (Exception e) {
                Log.e("Android", "");
                e.printStackTrace();
            } finally {
                client.close();
                Log.e("Android", "");
            }
            Thread.sleep(3000);
        }
    } catch (Exception e) {
        Log.e("Android", "");
        e.printStackTrace();
    } finally {
        if (serverSocket != null) {
            try {
                serverSocket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

PC 客户端代码：

try {
        // 6665是 PC 端的端口，通过运行该 Shell 命令重定向到 Android Device 的6666端口 (端口自己定，不得超过1023)
        Runtime.getRuntime().exec("[Your Android SDK's Dir]\\platform-tools\\adb.exe forward tcp:6665 tcp:6666");
    } catch (IOException e) {
        e.printStackTrace();
        return;
    }

    Socket socket = null;
    try {
        InetAddress serverAddr = null;
        serverAddr = InetAddress.getByName("127.0.0.1");
        System.out.println("Start to connect android");

        socket = new Socket(serverAddr, 6665);

        String message = "I'm pc";
        System.out.println("Pc is sending message: " + message);
        PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())), true);
        out.println(message);
        Thread.sleep(5000);

        // receive message from server (Android Device)
        BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        String msg = br.readLine();
        System.out.println(msg);
    } catch (UnknownHostException e) {
        System.out.println(e);
    } catch (IOException e) {
        System.out.println(e);
    } finally {
        try {
            if (socket != null) {
                socket.close();
            }
        } catch (IOException e) {
            System.out.println(e);
        }
    }
}