java - 套接字超时问题 : android client reading data from pc server

Question

我对 android、java 和套接字编程很陌生，所以我当然正在尝试合并这三者!

我正在创建一个基于桌面的java服务器，它将简单地发送一个短字符串到android应用程序(客户端)。

我的 Android 应用程序运行良好，它会将字符串发送到服务器，读取这些字符串没有任何问题。

我的服务器正在运行，它接收字符串没有任何问题。

但是，每当我尝试读取从服务器返回的字符串时，应用程序(客户端)就会出现套接字超时。我使用相同的代码，所以我无法理解这个问题。

无论如何，这是代码:

//SERVER//

import java.io.*;
import java.net.*;
import java.util.*;

public class GpsServer {

    ServerSocket serversocket = null;
    Socket socket = null;

    public GpsServer() 
    {
        try
        {
            serversocket = new ServerSocket(8189);
        } 
        catch (UnknownHostException unhe) 
        {
            System.out.println("UnknownHostException: " + unhe.getMessage());
        } 
        catch (InterruptedIOException intioe) 
        {
            System.out.println("Timeout while attempting to establish socket connection.");
        } catch (IOException ioe) 
        {
            System.out.println("IOException: " + ioe.getMessage());
        }
    }

    public void refreshServer() {

        try 
        {
            socket = serversocket.accept();

            InputStreamReader inputstreamreader = new InputStreamReader(socket.getInputStream());
            BufferedReader bufferedreader = new BufferedReader(inputstreamreader);
            PrintWriter printwriter = new PrintWriter(socket.getOutputStream(),true);

            System.out.println("socket read successful");
            printwriter.println("Send Bye to disconnect.");

            String lineread = "";
              boolean done = false;
              while (((lineread = bufferedreader.readLine()) != null) && (!done)){
                System.out.println("Received from Client: " + lineread);
                printwriter.println("You sent: " + lineread);
                if (lineread.compareToIgnoreCase("Bye") == 0) done = true;
              }

            System.out.println("Closing connection");

            socket.close();
            bufferedreader.close();
            inputstreamreader.close();
            printwriter.close();
        } 
        catch (UnknownHostException unhe) 
        {
            System.out.println("UnknownHostException: " + unhe.getMessage());
        } 
        catch (InterruptedIOException intioe)
        {
            System.out
                    .println("Timeout while attempting to establish socket connection.");
        } 
        catch (IOException ioe) 
        {
            System.out.println("IOException: " + ioe.getMessage());
        }
    }

    public void nullify() {     
        try 
        {
            socket.close();
            serversocket.close();
        } 
        catch (IOException ioe) 
        {
            System.out.println("IOException: " + ioe.getMessage());
        }
    }
}

还有客户...

//CLIENT

import java.io.*;
import java.net.*;
import java.util.*;

public class GpsClient {

    public String lastMessage;
    Socket socket = null;

    String serverurl;
    int serverport;

    public GpsClient() {
        lastMessage = "";

        serverport = 8189;
        serverurl = "192.168.10.4";

        try 
        {
            socket = new Socket(serverurl, serverport);
            socket.setSoTimeout(10000);
        } 
        catch (UnknownHostException unhe) 
        {
            System.out.println("UnknownHostException: " + unhe.getMessage());
        } 
        catch (InterruptedIOException intioe) 
        {
            System.out.println("Timeout while attempting to establish socket connection.");
        } 
        catch (IOException ioe) 
        {
            System.out.println("IOException: " + ioe.getMessage());
        }
    }

    public void retrieveNew() {

        try {
            socket = new Socket(serverurl, serverport);
            socket.setSoTimeout(10000);

            lastMessage = "connected!";

            InputStreamReader inputstreamreader = new InputStreamReader(socket.getInputStream());
            BufferedReader bufferedreader = new BufferedReader(inputstreamreader);

            PrintWriter printwriter = new PrintWriter(socket.getOutputStream(),true);
            printwriter.println("Request");

            lastMessage = "Request sent";

//          Get error when I uncomment this block, i.e. try to read the response from the server
//          "Timeout while attempting to establish socket connection."

//          String lineread = "";
//          while ((lineread = bufferedreader.readLine()) != null) {
//              System.out.println("Received from Server: " + lineread);
//              lastMessage = "Received from Server: " + lineread;
//          }

            lastMessage = "closing connection!";
            bufferedreader.close();
            inputstreamreader.close();
            printwriter.close();
            socket.close();

        } 
        catch (UnknownHostException unhe) 
        {
            System.out.println("UnknownHostException: " + unhe.getMessage());
        } 
        catch (InterruptedIOException intioe) 
        {
            System.out.println("Timeout while attempting to establish socket connection.");
        } 
        catch (IOException ioe) 
        {
            System.out.println("IOException: " + ioe.getMessage());
        } 
        finally 
        {
            try 
            {
                socket.close();
            } 
            catch (IOException ioe) 
            {
                System.out.println("IOException: " + ioe.getMessage());
            }
        }
    }

    public void nullify() {
        try 
        {
            PrintWriter printwriter = new PrintWriter(socket.getOutputStream(),true);
            printwriter.println("Bye");
            printwriter.close();
            socket.close();
        }
        catch (IOException ioe) 
        {
            System.out.println("IOException: " + ioe.getMessage());
        }
    }
}

提前致谢!

乔什

Answer 1

除了我评论中提到的所有问题之外，您正在客户端中创建两个套接字，而您的服务器仅被写入处理一个连接。因此，它写入第一个并尝试从中读取，同时您的客户端正在写入第二个并尝试从中读取。

当你解决这个问题时，你就会陷入僵局，因为双方都在尝试互相读取。

此外，您不应该通过网络使用 PrintWriter 或 PrintStream，因为它们会吞掉您需要了解的异常。使用 BufferedWriter。