我正在 Android 模拟器上创建和测试一个简单的 TCP 服务器。

我使用一个简单的 Java 客户端程序尝试连接到在模拟器上运行的服务器。我尝试发送一个简单的字符串，如“hello world”。

我认为客户端和服务器之间的连接初始化成功；但是，数据不会路由到 Android 设备。

服务器线程阻塞在 clientSentence = inFromClient.readLine(); 行，客户端线程阻塞在 String serverResponse = inFromServer.readLine();。

根据 Google docs，我已将本地主机端口 6100 端口转发到 AVD 虚拟端口 7100使用 ADB

adb -s emulator-5554 forward tcp:6100 tcp:7100

这是 Java 类 TCPTestClient

public class TCPTestClient
{
   public static void main(String argv[]) throws Exception
   {
      String sentenceToServer = "hello server";
      System.out.println("initializing socket");
      Socket clientSocket = new Socket("127.0.0.1", 6100);
      System.out.println("socket initialized");
      System.out.println("getting output stream to server");
      DataOutputStream outToServer = new DataOutputStream(clientSocket.getOutputStream());
      System.out.println("found output stream to server");
      System.out.println("getting input stream from server");
      BufferedReader inFromServer = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
      System.out.println("found input stream from server");
      System.out.println("writing sentence to server");
      outToServer.writeBytes(sentenceToServer );
      System.out.println("sentence written");
      System.out.println("waiting for sentence response from server");
      String serverResponse = inFromServer.readLine();
      System.out.println("serverResponse = "+serverResponse);
      System.out.println("socket closed");
      clientSocket.close();
   }
}

这是 Android 应用程序方法 initTcpTestServer()

private void initTcpTestServer()
{
  Log.d("TAG", "initTcpTestServer()");
  try
  {

     String clientSentence;
     ServerSocket welcomeSocket = new ServerSocket(7100);

     while ( true )
     {
        Log.d("TAG", "looking for socket");
        Socket connectionSocket = welcomeSocket.accept();
        Log.d("TAG", "socket accepted");
        Log.d("TAG", "getting input stream");
        BufferedReader inFromClient = new BufferedReader(
              new InputStreamReader(connectionSocket.getInputStream()));
        Log.d("TAG", "input stream found");
        Log.d("TAG", "getting output stream");
        DataOutputStream outToClient = new DataOutputStream(connectionSocket.getOutputStream());
        Log.d("TAG", "output stream found");
        Log.d("TAG", "reading input stream");
        clientSentence = inFromClient.readLine();
        Log.d("TAG", "input stream read");
        Log.d("TAG", "input = " + clientSentence);
        Log.d("TAG", "writing output back to client");
        outToClient.writeBytes(clientSentence);
        Log.d("TAG", "output written back to client");
     }
  }
  catch ( IOException e )
  {
     e.printStackTrace();
  }
}

如果我先初始化 TCP 服务器，我会得到输出

initTcpTestServer()
looking for socket

初始化TCP服务器后，再初始化我从服务器获取的TCP客户端

getting input stream
input stream found
getting output stream
output stream found
reading input stream

来自客户

initializing socket
socket initialized
getting output stream to server
found output stream to server
getting input stream from server
found input stream from server
writing sentence to server
sentence written
waiting for sentence response from server

所以看起来套接字已经建立，但是服务器阻塞在行

clientSentence = inFromClient.readLine();

客户端 block 在

String serverResponse = inFromServer.readLine();

因为客户端已经写入了数据，但是服务端一直没有收到，客户端一直挂着等待服务端的响应。

最佳答案

谢谢可怕的袋熊。在字符串末尾添加“\n”会导致向服务器成功发送 TCP 消息。通过在带有 ADB 的 AVD 虚拟路由器上配置端口转发，确实可以在 Android 模拟器上设置 TCP 服务器。但是，我只在本地主机上对此进行了测试。

关于java - 如何建立 TCP 连接并将数据发送到 Android Virtual Device App，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/55583787/