Question

我正在尝试在Netbeans上运行java中的客户端 - 服务器程序。

以下是服务器的代码：

// File Name GreetingServer.java

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

public class GreetingServer extends Thread
{
   private ServerSocket serverSocket;

   public GreetingServer(int port) throws IOException
   {
      serverSocket = new ServerSocket(port);
      serverSocket.setSoTimeout(10000);
   }

   public void run()
   {
      while(true)
      {
         try
         {
            System.out.println("Waiting for client on port " +
            serverSocket.getLocalPort() + "...");
            Socket server = serverSocket.accept();
            System.out.println("Just connected to "
                  + server.getRemoteSocketAddress());
            DataInputStream in =
                  new DataInputStream(server.getInputStream());
            System.out.println(in.readUTF());
            DataOutputStream out =
                 new DataOutputStream(server.getOutputStream());
            out.writeUTF("Thank you for connecting to "
              + server.getLocalSocketAddress() + "\nGoodbye!");
            server.close();
         }catch(SocketTimeoutException s)
         {
            System.out.println("Socket timed out!");
            break;
         }catch(IOException e)
         {
            e.printStackTrace();
            break;
         }
      }
   }
   public static void main(String [] args)
   {
      int port = Integer.parseInt(args[0]); #line 48, error arises here. 
      try
      {
         Thread t = new GreetingServer(port);
         t.start();
      }catch(IOException e)
      {
         e.printStackTrace();
      }
   }
}

以下是客户端的代码：

// File Name GreetingClient.java

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

public class GreetingClient
{
   public static void main(String [] args)
   {
      String serverName = args[0]; #line 10, error arises here 
      int port = Integer.parseInt(args[1]);
      try
      {
         System.out.println("Connecting to " + serverName
                             + " on port " + port);
         Socket client = new Socket(serverName, port);
         System.out.println("Just connected to "
                      + client.getRemoteSocketAddress());
         OutputStream outToServer = client.getOutputStream();
         DataOutputStream out =
                       new DataOutputStream(outToServer);

         out.writeUTF("Hello from "
                      + client.getLocalSocketAddress());
         InputStream inFromServer = client.getInputStream();
         DataInputStream in =
                        new DataInputStream(inFromServer);
         System.out.println("Server says " + in.readUTF());
         client.close();
      }catch(IOException e)
      {
         e.printStackTrace();
      }
   }
}

因此，当我想模拟客户端和服务器一起运行时，我首先运行服务器。服务器运行后，我需要运行客户端。

但是，当我尝试运行服务器文件时，出现以下错误：

运行：线程“main”中的异常java.lang.ArrayIndexOutOfBoundsException：0 在GreetingServer.main（GreetingServer.java:48） Java结果：1 建立成功（总时间：0秒）

同样，当我尝试运行客户端程序时，出现以下错误：

运行：线程“main”中的异常java.lang.ArrayIndexOutOfBoundsException：0 在GreetingClient.main（GreetingClient.java:10） Java结果：1 建立成功（总时间：0秒）

为什么会这样？请帮忙。

更新

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

public class GreetingServer extends Thread
{
    private static int port;
   private ServerSocket serverSocket;

   public GreetingServer(int port) throws IOException
   {
      serverSocket = new ServerSocket(port);
      serverSocket.setSoTimeout(10000);
   }

   public void run()
   {
      while(true)
      {
         try
         {
            System.out.println("Waiting for client on port " +
            serverSocket.getLocalPort() + "...");
            Socket server = serverSocket.accept();
            System.out.println("Just connected to "
                  + server.getRemoteSocketAddress());
            DataInputStream in =
                  new DataInputStream(server.getInputStream());
            System.out.println(in.readUTF());
            DataOutputStream out =
                 new DataOutputStream(server.getOutputStream());
            out.writeUTF("Thank you for connecting to "
              + server.getLocalSocketAddress() + "\nGoodbye!");
            server.close();
         }catch(SocketTimeoutException s)
         {
            System.out.println("Socket timed out!");
            break;
         }catch(IOException e)
         {
            e.printStackTrace();
            break;
         }
      }
   }
   public static void main(String [] args)
   {
      port=9000;
      try
      {
         Thread t = new GreetingServer(port);
         t.start();
      }catch(IOException e)
      {
         e.printStackTrace();
      }
   }
}


// File Name GreetingClient.java

import java.io.*;
import java.net.*;
public class GreetingClient
{
    private static String serverName;
   public static void main(String [] args)
   {
      String sName = "MyServerName";
      int port = 9000;
      try
      {
         System.out.println("Connecting to " + sName
                             + " on port " + port);
         Socket client = new Socket(sName, port);
         System.out.println("Just connected to "
                      + client.getRemoteSocketAddress());
         OutputStream outToServer = client.getOutputStream();
         DataOutputStream out =
                       new DataOutputStream(outToServer);

         out.writeUTF("Hello from "
                      + client.getLocalSocketAddress());
         InputStream inFromServer = client.getInputStream();
         DataInputStream in =
                        new DataInputStream(inFromServer);
         System.out.println("Server says " + in.readUTF());
         client.close();
      }catch(IOException e)
      {
      }
   }
}

现在服务器端没有错误。但我仍然在客户端收到以下错误：

运行：线程“main”中的异常java.lang.ArrayIndexOutOfBoundsException：0 在GreetingClient.main（GreetingClient.java:10） Java结果：1 建立成功（总时间：0秒）

Answer 1

要运行SocketServer，您需要在哪个服务器上运行端口。例如：

SocketServer server = new SocketServer(1234);

问题是你想通过java参数传递端口而你没有这样做。首先，在使用任何变量之前，您应首先验证它。

if (args.length>0) {
    int port = Integer.parseInt(args[0]); #line 48, error arises here. 
}

你的程序需要参数，但我认为你可能没有params运行你的程序。您应该以这种方式运行程序：java -jar app.jar 1234 但是你这样做：java -jar app.jar

在本文中，您将了解如何使用netbeans http://netbeanside61.blogspot.com/2009/02/using-command-line-arguments-in.html将参数传递给java程序。

如果您是Java新手，请先阅读本教程http://docs.oracle.com/javase/tutorial/networking/sockets/。这非常有帮助。

Answer 2

您的代码假设您将要用作参数的端口传递给：

您使用PatrykRoszczyniała发布的应用程序运行您的应用程序

如果您不想使用它，只需删除以下行：

String serverName = args[0]; 
int port = Integer.parseInt(args[0]);

并将其替换为硬编码值，例如：

String serverName = "MyServerName";
int port = 3000;

更新：

我刚刚测试了你的代码，事实上，serverName是你用来连接服务器的地址，所以如果你在同一台机器上同时运行客户端和服务器，则用"localhost"替换它。

经过测试的代码：

这是我测试的更新代码，如果你在同一台机器上运行，它应该可以正常工作。

客户：

import java.io.*;
import java.net.*;
public class GreetingClient
{
    private static String serverName;
   public static void main(String [] args)
   {
      String sName = "localhost";
      int port = 9000;
      try
      {
         System.out.println("Connecting to " + sName
                             + " on port " + port);
         Socket client = new Socket(sName, port);
         System.out.println("Just connected to "
                      + client.getRemoteSocketAddress());
         OutputStream outToServer = client.getOutputStream();
         DataOutputStream out =
                       new DataOutputStream(outToServer);

         out.writeUTF("Hello from "
                      + client.getLocalSocketAddress());
         InputStream inFromServer = client.getInputStream();
         DataInputStream in =
                        new DataInputStream(inFromServer);
         System.out.println("Server says " + in.readUTF());
         client.close();
      }catch(IOException e)
      {
      }
   }
}

服务器：

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

public class GreetingServer extends Thread
{
    private static int port;
   private ServerSocket serverSocket;

   public GreetingServer(int port) throws IOException
   {
      serverSocket = new ServerSocket(port);
      serverSocket.setSoTimeout(20000);
   }

   public void run()
   {
      while(true)
      {
         try
         {
            System.out.println("Waiting for client on port " +
            serverSocket.getLocalPort() + "...");
            Socket server = serverSocket.accept();
            System.out.println("Just connected to "
                  + server.getRemoteSocketAddress());
            DataInputStream in =
                  new DataInputStream(server.getInputStream());
            System.out.println(in.readUTF());
            DataOutputStream out =
                 new DataOutputStream(server.getOutputStream());
            out.writeUTF("Thank you for connecting to "
              + server.getLocalSocketAddress() + "\nGoodbye!");
            server.close();
         }catch(SocketTimeoutException s)
         {
            System.out.println("Socket timed out!");
            break;
         }catch(IOException e)
         {
            e.printStackTrace();
            break;
         }
      }
   }
   public static void main(String [] args)
   {
      port=9000;
      try
      {
         Thread t = new GreetingServer(port);
         t.start();
      }catch(IOException e)
      {
         e.printStackTrace();
      }
   }
}

在NetBeans上运行用Java编写的客户机 - 服务器程序

2 个答案: