在NetBeans上运行用Java编写的客户机-服务器程序

我正在尝试在Netbeans上用java运行一个客户机-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”java.lang.ArrayIndexOutOfBoundsException中出现异常：0 位于GreetingServer.main（GreetingServer.java:48） Java结果：1 生成成功（总时间：0秒）

类似地，当我尝试运行客户端程序时，会出现以下错误：

运行： 线程“main”java.lang.ArrayIndexOutOfBoundsException中出现异常：0 位于GreetingClient.main（GreetingClient.java:10） Java结果：1 生成成功（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)
      {
      }
   }
}

服务器端现在没有错误。但我仍然在客户端遇到以下错误：

运行： 线程“main”java.lang.ArrayIndexOutOfBoundsException中出现异常：0 位于GreetingClient.main（GreetingClient.java:10） Java结果：1

---

构建成功（总时间：0秒）

要运行

SocketServer

，您需要传递服务器将工作的端口。例如：

SocketServer server = new SocketServer(1234);

问题是您希望通过java参数传递端口，但您没有这样做。首先，在使用任何变量之前，您应该首先验证它

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

您的程序需要params，但我认为您可能在没有params的情况下运行程序。 您应该这样运行程序：

java-jarapp.jar1234

但是您可以这样做：

java-jarapp.jar

在本文中，您将了解如何使用netbeans将参数传递给java程序

---

如果您是java新手，应该首先阅读本教程。这非常有用。

您的代码假定您传递了要用作参数的端口，因此：

• 要么使用Patryk Roszczyniała发布的行运行应用程序

• 如果不想使用，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，如：

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

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)
      {
      }
   }
}

我刚刚测试了您的代码，事实上，serverName是用于连接到服务器的地址，因此，如果您在同一台计算机上同时运行客户端和服务器，请将其替换为

“localhost”

测试代码：

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)
      {
      }
   }
}

这是我测试的更新代码，如果在同一台机器上运行这两个代码，它应该可以完美地工作

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();
      }
   }
}

---

当你运行你的程序时，你是否向它传递任何参数？你如何运行服务器？不，我不是。如果我应该，那么我应该在哪里以及如何传递它们？右键单击.java文件并选择Runplease查看更新您在客户端也遇到了同样的问题。您试图将

arg[0]

作为端口传递，但

arg

数组为空。您应该在使用arg数组之前验证它，并使用命令行为客户端传递端口，或者只为客户端硬编码端口。再看一看，我已经硬编码了端口号。现在是：String sName=“MyServerName”；int端口=9000；你仍然有异常？此外，为什么我不再使用args[]时仍然将数组索引作为异常处理？我认为你应该先阅读这篇文章。我编译并运行了你的代码，没有异常，但你必须将服务器名设置为“localhost”以使其连接。检查我的编辑我向您发布了我测试过的更新代码，检查一下，只要在Eclipse中同时运行这两个代码，它就可以在我的计算机上完美运行。我将您的代码复制并粘贴到Netbeans中，但仍然不起作用。我收到了相同的错误：run:Exception in thread“main”java.lang.ArrayIndexOutOfBoundsException:0 at GreetingClient.main（GreetingClient.java:10）java结果：1生成成功（总时间：0秒）如果仍然出现异常，请告诉我现在如何运行它？如果通过启动.jar来运行它，请确保在更正后重新生成可执行文件.jar。