java 数据输出流异常

Question

当我第二次输入某些内容时（在输入主机名之后），第 24 行会抛出异常 - 服务器工作正常。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java新手，所以我想我错过了一些明显的东西。异常内容如下：

线程“main”中出现异常 java.net.SocketException：软件 导致连接中止：套接字写入 错误 在 java.net.SocketOutputStream.socketWrite0（本机方法） 在 java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:92) 在 java.net.SocketOutputStream.write(SocketOutputStream.java:115) 在 java.io.DataOutputStream.writeBytes(DataOutputStream.java:259) 在 TCPclient.main(TCPClient.java:52) Java 结果：1

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遍又一遍地向该套接字写入数据。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();

接受传入连接，读取一行，然后放弃它（我猜测在垃圾收集时套接字的完成会关闭连接）。然后它等待新的连接。

因此，要解决眼前的问题，请尝试

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

在 while 循环之前移动。

Answer 2

输入第二行之间要等待多长时间？这可能与套接字空闲有关。

同样，使用这样的服务器代码，您只会看到第一条消息。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");
    }
}

注意变化：

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

而

... "\n"); 

不是

... '\n');

试一试。这可能是一个太简单的解决方案，但它确实是:)