java DataOutputStream异常

Question

第二次(在键入主机名之后)-服务器正常工作时，将在第24行抛出异常。代码

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

class TCPclient {
    public static void main(String[] args) throws Exception {
        String hostname, msg;
        InetAddress hostaddress;
        BufferedReader inFromUser = new BufferedReader (new InputStreamReader(System.in));
        System.out.println("Please type host\n");
        hostname = inFromUser.readLine();   //I type localhost
        hostaddress = InetAddress.getByName(hostname);
        Socket cSocket = new Socket(hostaddress, 44444);
        String cAddress = cSocket.getLocalSocketAddress().toString();
        DataOutputStream outToServer = new DataOutputStream (cSocket.getOutputStream());
        while (true)
        {
            msg = inFromUser.readLine();
            System.out.println(msg);
            if (msg.equals("exit"))
            {
                System.out.println("exit");
                break;
            }
            outToServer.writeBytes(cAddress + " said : " + msg + '\n'); //this line throws an exception the second time it runs
        }
        cSocket.close();
    }
}

我是新加入java的，所以我忽略了一些显而易见的东西。例外情况如下：

线程"main“中的java.net.SocketOutputStream.socketWrite0(Native异常:软件导致连接中止: java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:92) at java.net.SocketOutputStream.write(SocketOutputStream.java:115) at java.io.DataOutputStream.writeBytes(DataOutputStream.java:259) at TCPclient.main(TCPClient.java:52)

服务器：

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

class TCPServer {
   public static void main(String argv[]) throws Exception {
      String clientSentence;
      ServerSocket welcomeSocket = new ServerSocket(44444);
      while(true) {
         Socket connectionSocket = welcomeSocket.accept();
         BufferedReader inFromClient = new BufferedReader(
                new InputStreamReader(connectionSocket.getInputStream( ) ) );
         clientSentence = inFromClient.readLine();
         System.out.println(clientSentence + "\n");
      }
   }
}

Answer 1

您的客户端创建一个套接字，并一次又一次地写入该套接字。另一方面，您的服务器执行以下操作：

ServerSocket welcomeSocket = new ServerSocket(44444);
while(true) {
   Socket connectionSocket = welcomeSocket.accept();

它接受传入的连接，读取一行，然后放弃它(当垃圾收集时，我猜在套接字的finalize上，它关闭了连接)。然后它等待一个新的连接。

因此，要解决眼前的问题，请尝试移动。

    Socket connectionSocket = welcomeSocket.accept();
    BufferedReader inFromClient = new BufferedReader(
            new InputStreamReader(connectionSocket.getInputStream( ) ) );

在while循环之前。

Answer 2

键入第二行要等多长时间？这可能与套接字闲置有关。

同样，使用这样的服务器代码，您将只看到第一条消息。试试这个：

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

class TCPServer {
    public static void main(String argv[]) throws Exception {
        String clientSentence;
        ServerSocket welcomeSocket = new ServerSocket(44444);
        Socket connectionSocket = welcomeSocket.accept();
        BufferedReader inFromClient = new BufferedReader(new InputStreamReader(connectionSocket.getInputStream()));
        while (true) {
            clientSentence = inFromClient.readLine();
            System.out.println(clientSentence + "\n");
        }
    }
}

Answer 3

尝试：

while (true)
{
    if(inFromUser.readLine() != null)
    {        
        msg = inFromUser.readLine();

        System.out.println(msg);
        if (msg.equals("exit"))
        {
           System.out.println("exit");
           break;
        }

        outToServer.writeBytes(cAddress + " said : " + msg + "\n");
    }
}

请注意以下更改：

if(inFromUser.readLine() != null)
{ 

和

... "\n"); 

不

... '\n');

试试看。这可能是一个过于简单的解决方案，但它确实是这样的:)