使用 Android 模拟器通过 IP 和端口访问网络设备 [英] Reaching a network device by IP and port using the Android emulator

问题描述

为什么我的 Android 版 Java 应用无法连接到服务器?

Why does my Java app for Android not connect to the server?

我在 Android 模拟器中运行该应用程序，服务器位于端口 9999 和主机 127.0.0.1 在我的电脑中，但它无法连接，我认为这种方法不适用于 Sndroid 应用程序.

I run the application in Android emulator, and the server which is on port 9999 and host 127.0.0.1 in my pc, but it will just not connect and I think this method isn't good for Sndroid app.

更新:我使用 API 8 和 Android 2.2

这是我的源代码:

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
//Java imports
//import android.util.Log;
import java.io.*;
import java.net.*;
import java.util.*;
import java.util.logging.Level;
import java.util.logging.Logger;


public class MainActivity extends Activity{
//Variaveis Interface
private Button ligar;
private Button enviar;
private EditText text1;
private TextView text2;
//Variaveis
static Socket cSocket;
static PrintWriter out;
static BufferedReader in;
   

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    
    //Declaração butões
    ligar = (Button) findViewById(R.id.ligar);
    enviar = (Button) findViewById(R.id.enviar);
    text1 = (EditText) findViewById(R.id.text1);
    text2 = (TextView) findViewById(R.id.text2);

    //Interacao
    ligar.setOnClickListener(new OnClickListener(){
        public void onClick(View arg0){
             connect();
        }
    });
    enviar.setOnClickListener(new OnClickListener(){
        public void onClick(View arg0){
               out.println("Hello");
               text2.setText("");
        }
    });
  }
  //Outras Funcoes

public void connect(){
//Funcao ligar
cSocket = null;
out = null;
in = null;

try{
   cSocket = new Socket("10.0.2.2",4444);
   out = new PrintWriter(cSocket.getOutputStream(), true);
   in = new BufferedReader(new InputStreamReader(cSocket.getInputStream()));
   text2.setText("Estas conectado com sucesso.");
   }
   catch (IOException ex) {
   //Logger.getLogger(client.class.getName()).log(Level.SEVERE, null, ex);
   text2.setText("Erro! Na conexão");
   }                
   }
//
}

推荐答案

见这里:

可以使用模拟器的 IP 地址 10.0.2.2 访问主机.

Host machine can be reached using IP address 10.0.2.2 from the emulator.

**编辑，回复您的评论:*

**edit, answer to your comment:*

为了完整性和更好地理解我的回答，请阅读 Android 模拟器文档.

For completeness and to better understand my answer, read the Android Emulator documentation.

这些是从模拟器获得的 IP 地址:

These are the IP addresses as reached from the emulator:

• 10.0.2.1，路由器/网关地址.
• 10.0.2.2，主机环回接口的特殊别名(即开发机器上的 127.0.0.1)
• 10.0.2.3，第一个 DNS 服务器
• 10.0.2.4/10.0.2.5/10.0.2.6，可选第二、第三、第四个DNS服务器(如果有)
• 10.0.2.15，模拟设备自己的网络/以太网接口
• 127.0.0.1，模拟设备自己的环回接口

• 10.0.2.1, Router/gateway address.
• 10.0.2.2, Special alias to your host loopback interface (i.e., 127.0.0.1 on your development machine)
• 10.0.2.3, First DNS server
• 10.0.2.4 / 10.0.2.5 / 10.0.2.6, Optional second, third and fourth DNS server (if any)
• 10.0.2.15, The emulated device's own network/ethernet interface
• 127.0.0.1, The emulated device's own loopback interface

也就是说，我们有:

• 常见错误 1:从试图访问主机的模拟器访问 127.0.0.1.正如我所说，使用 10.0.2.2.
• 常见错误 2:尝试访问 HostComputerIP:appServicePort 上的模拟器服务.由于您的主机计算机本身(Windows、Linux、OS 等)没有在该端口中运行服务，因此它无法工作.您需要将模拟器控制台上的端口重定向到模拟Android 实例本身上的端口(请参阅下面的 2).

• Common mistake 1: accessing 127.0.0.1 from the emulator trying to reach your host machine. Use 10.0.2.2, as I said.
• Common mistake 2: Trying to access an emulator service on HostComputerIP:appServicePort. It won't work since your host computer itself (Windows, Linux, OS etc.) is not running a service in that port. You need to redirect a port on the emulator console to a port on an emulated Android instance itself (see 2 below).

常见的网络需求:

1- 模拟器应用程序作为客户端，本地计算机作为服务器

因为模拟器是NAT'd，我相信你可以直接连接到本地网络上的任何计算机.我的意思是，由于虚拟路由器可以访问两个网络，它应该能够很好地处理传出(即模拟器->真实局域网)连接.

Because the emulator is NAT'd, I believe you can connect to any computer on your local network directly. I mean, since the virtual router has access to both networks, it should be able to handle outgoing (i.e., emulator->real lan) connections just fine.

示例: 在我的网络 (192.168.0.x) 上，我可以将从模拟器连接到我的真实路由器(192.168.0.254) 只需将模拟器网络浏览器指向 http://192.168.0.254:port.我在它上面使用了不同的服务(向 Tomato 致敬！)，我可以在每个 port 上访问所有这些服务.无需处理端口转发，如预期.

Example: on my network (192.168.0.x), I can connect from the emulator to my real router (192.168.0.254) just pointing the emulator web browser to http://192.168.0.254:port. I use different services on it (hail to Tomato!), and I can access all of them on each port. No need to handle port forwarding, as expected.

根据您的代码，我相信您需要:

// I assume 192.168.0.114 is your server, which is
// located on your local network, running a server application
// on port 9999.
cSocket = new Socket("192.168.0.114",9999);

2- 本地计算机作为客户端，模拟器应用程序作为服务器

现在是另一回事了.您需要在虚拟机上设置端口重定向 路由器.最简单的方法是:

Now that's a different story. You need to setup port redirections on the virtual router. The easiest way is:

从您的主机(您的计算机、Linux 上的控制台或 Windows 上的命令提示符)Telnet 进入管理"系统(这不是模拟器):

Telnet into the "management" system (this is not the emulator), from your host (your computer, console on linux or command prompt on Windows):

telnet localhost 5554

之后，使用:

adb forward tcp:localPort tcp:emulatorPort

此后，您将能够在 emulatorPort 上获得服务，并且您将能够通过访问 hostComputerIP:localPort 从本地网络中的计算机连接到它.

After this, you will be able to have a service on emulatorPort and you will be able to connect to it from computers in the local network by accessing hostComputerIP:localPort.

这是人们(包括我)使用的方式，例如在模拟器中使用 SSHDroid.

This is the way people (including me) use, for example, SSHDroid inside an emulator.

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