为什么 getProperty 方法不打印出工作目录？

Question

我正在尝试构建一个简单的客户端-服务器应用程序。现在我想打印出服务器的当前工作目录。我试过使用 String workingDir= System.getProperty("user.dir"); 方法。但它实际上并没有打印出目录。我不知道为什么。我需要帮助。

   package clint;
import java.io.*;
import java.net.*;
import java.util.Scanner;

public class AreaClient{
   private static final int PORT = 8000;
    private static final String SERVER = "194.47.46.146";

    public static void main ( String [] args ){
       String server = "localhost";
       int port = PORT;

        if ( args.length >= 1 )
          server = args[0];
        if (args.length >= 2)
          port = Integer.parseInt( args[1]);

        new AreaClient ( server, port ); 
    }

    public AreaClient( String server, int port ){
      DataInputStream inputFromServer;
      DataOutputStream outputToServer;

      try {
        // create a socket to connect to the server
        Socket socket = new Socket( server, port );

         // create data input/output streams
         inputFromServer = new DataInputStream( socket.getInputStream( ) );
         outputToServer = new DataOutputStream( socket.getOutputStream( ) );

         // create Scanner object to read command from the keyboard
         Scanner sc = new Scanner ( System.in );
         System.out.print("Enter pwd command = ");
         while ( sc.hasNext()){
            // get the pwd command
             String command = sc.nextLine();

             // send the pwd command to sever
             outputToServer.writeBytes(command );
             outputToServer.flush( );

             // get working directory from server
             String workingDir = inputFromServer.readUTF();

             System.out.println("Working directory is: " + workingDir);

         }
         inputFromServer.close();
         outputToServer.close();
         socket.close( );
        } catch ( IOException e ){
          System.err.println( e );
        }

    }

}




package server;
import java.io.*;
import java.net.*;

public class AreaServer{
   private static final int PORT = 8000;
    private ServerSocket serverSocket;

    public static void main ( String [] args ){
       int port = PORT;
        if ( args.length == 1 )
           port = Integer.parseInt( args[0] );  
        new AreaServer( port );
    }

    public AreaServer( int port ){
      // create a server socket
      try {
          serverSocket = new ServerSocket( port );
      } catch ( IOException e ) {
         System.err.println( "Error in creation of the server socket");
          System.exit( 0 );
      }

      while ( true ) {
        try {
           // listen for a connection
            Socket socket = serverSocket.accept( ) ;

             // create data input/output streams
             DataInputStream inputFromClient = new DataInputStream( socket.getInputStream( ));
            DataOutputStream outputToClient = new DataOutputStream( socket.getOutputStream( ) );

             // loop to service a client
            while ( true ){
                //receive command from client
              String command = inputFromClient.readUTF();

              //getting the directory
              String workingDir=  System.getProperty("user.dir");

              //send the working directory to client
              outputToClient.writeBytes(workingDir );
             } 

            } catch ( IOException e ){
              System.err.println( e );
            }
        }
    }
}

Answer 1

我认为这个问题可能更基本一些。您正在客户端上执行 writeBytes() 并在服务器上执行 readUTF() ，反之亦然。如果您坚持使用 writeBytes() / readBytes() 或 writeUTF() / readUTF() 组合会更好。不要将两者混为一谈。

来自javadoc of DataInput#readUTF()

The writeUTF method of interface DataOutput may be used to write data that is suitable for reading by this method.

为什么 getProperty 方法不打印出工作目录？

Why getProperty method doesn't print out the working directory?

java

sockets

client-server

inputstream

outputstream