如何从 Android Tcp 客户端套接字连接到具有 Public IP 的 Java TCP 服务器套接字？

Question

我的工作地点有两个真实IP地址220.xx.xxx.xxx。我试图制作一个简单的 java tcp 服务器程序和 android tcp 客户端程序。 android 客户端在以下情况下工作正常：

Server and emulator program in the same pc.

Server in one pc having real IP address emulator is in another pc with a real ip address.

Server and emulator both within under private network within same pc or different pc or device.

在以下情况下不起作用：

client is a smart phone having wifi or 3g network, and server have a real IP address on different network.

client is an emulator running on wifi connected device, server have a real ip address.

那么，如何从 Android Tcp 客户端套接字连接到具有 Public IP 的 Java TCP 服务器套接字？我不认为粘贴代码在这里真的是必要的。但是，如果有人问我可以提供。根据我在互联网上的搜索，有人提供了在服务器端配置路由器的建议。这在我看来有点烦人。如果我运行一个网络服务器，它可以从任何地方访问。此处包含的代码：服务器端：

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.DataInput;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.*;

public class Server {

    private static ServerSocket serverSocket;
    private static Socket clientSocket;
    private static InputStreamReader inputStreamReader;
    private static BufferedReader bufferedReader;
    private static OutputStreamWriter outputStreamWriter;
    private static BufferedWriter bufferedWriter;
    private static PrintWriter printWriter;
    private static String message;
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        try {
            System.out.println(InetAddress.getLocalHost());
            serverSocket = new ServerSocket(4444); // Server socket

        } catch (IOException e) {
            System.out.println("Could not listen on port: 4444");
        }

        System.out.println("Server started. Listening to the port 4444");

        while (true) {
            try {

                clientSocket = serverSocket.accept(); // accept the client connection
                System.out.println("connection initiated");

                DataInputStream din = new DataInputStream(clientSocket.getInputStream());

                DataOutputStream dout= new DataOutputStream(clientSocket.getOutputStream());

                String msg = din.readUTF();
                System.out.println(msg);

                dout.writeUTF("hello from server");
                System.out.println("sent to client");



                clientSocket.close();

            } catch (IOException ex) {
                System.out.println("Problem in message reading "+ex);
            }
        }
    }

}

客户端：

package com.example.client;
import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;

import android.os.AsyncTask;
import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends Activity {

 TextView textResponse;
 EditText editTextAddress, editTextPort; 
 Button buttonConnect, buttonClear;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);

  editTextAddress = (EditText)findViewById(R.id.address);
  editTextPort = (EditText)findViewById(R.id.port);
  buttonConnect = (Button)findViewById(R.id.connect);
  buttonClear = (Button)findViewById(R.id.clear);
  textResponse = (TextView)findViewById(R.id.response);

  buttonConnect.setOnClickListener(buttonConnectOnClickListener);

  buttonClear.setOnClickListener(new OnClickListener(){

   @Override
   public void onClick(View v) {
    textResponse.setText("");
   }});
 }

 OnClickListener buttonConnectOnClickListener = 
   new OnClickListener(){

    @Override
    public void onClick(View arg0) {
     MyClientTask myClientTask = new MyClientTask(
       editTextAddress.getText().toString(),
       Integer.parseInt(editTextPort.getText().toString()));
     myClientTask.execute();
    }};

 public class MyClientTask extends AsyncTask<Void, Void, Void> {

  String dstAddress;
  int dstPort;
  String response = "";

  MyClientTask(String addr, int port){
   dstAddress = addr;
   dstPort = port;
  }
  private PrintWriter printwriter;
  private InputStreamReader inputStreamReader;
  private BufferedReader bufferedReader;
  @Override
  protected Void doInBackground(Void... arg0) {

   Socket socket = null;

   try {
    socket = new Socket(dstAddress, dstPort);

    DataInputStream din = new DataInputStream(socket.getInputStream());
    DataOutputStream dout = new DataOutputStream(socket.getOutputStream());

    dout.writeUTF("hello from client");

    response="sent to serve;r";

    String msg = din.readUTF();
    response+=msg;

    socket.close();

   } catch (Exception e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
    response = e.toString();
   }
   return null;
  }

  @Override
  protected void onPostExecute(Void result) {
   textResponse.setText(response);
   super.onPostExecute(result);
  }

 }

}

Answer 1

为了 TCP connections 在真实设备上工作，您需要提供公共托管域的 URL。 localhost 或本地网络 URL 仅适用于同一本地网络上 a PC 上的 an emulator。

参考文献：

1. Emulator Networking.

2.

3. Accessing localhost:port from Android emulator

4. Calling web service from android device

5. Connect an Android Device To a Web Service on Local Host

6. How can I access my localhost from my Android device?

7. How to browse localhost on android device?

Answer 2

我刚刚将端口号从 4444 更改为 6667，现在到处都可以使用了。我不认为端口 4444 在其他地方使用，因为该程序在本地网络上运行

如何从 Android Tcp 客户端套接字连接到具有 Public IP 的 Java TCP 服务器套接字？

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