我正在尝试让客户端与Java中的服务器进行通信，客户端只是简单地发送要搜索的文件名，服务器应该回答文件夹中是否存在文件。 这是我写的代码。

client.java

import java.io.*;
import java.net.*;
import java.util.concurrent.*;

public class client{
    public static void main(String args[]) throws IOException,NumberFormatException,InterruptedException{
        Socket client_socket = new Socket(args[0],Integer.parseInt(args[1])); 
        System.out.println("connected\n");


        BufferedWriter netOut = new BufferedWriter(new OutputStreamWriter(client_socket.getOutputStream(),"UTF-8"));
        BufferedReader netIn = new BufferedReader(new InputStreamReader(client_socket.getInputStream(),"UTF-8"));

        netOut.write(args[2]);
        netOut.flush();

        String exist = netIn.readLine();

        System.out.println("The file you searched"+ exist);


        client_socket.close();
    }
}

args [0]用作本地主机，args [1]用作端口，args [2]用作要搜索的文件的名称。

server.java

import java.io.*;
import java.net.*;
import java.util.concurrent.*;

public class server{
    public static void main(String args[]) throws IOException,InterruptedException{

        ServerSocket sock_server = new ServerSocket(Integer.parseInt(args[0]));

        while(true){
            Socket communication = sock_server.accept();
            System.out.println("connected!\n");

            BufferedWriter netOut = new BufferedWriter(new OutputStreamWriter(communication.getOutputStream(),"UTF-8"));
            BufferedReader netIn = new BufferedReader(new InputStreamReader(communication.getInputStream(),"UTF-8"));

            String fileName = new String();
            fileName = netIn.readLine();

            System.out.println("The name of the file is"+fileName);

            File tempFile = new File(fileName);
            boolean exists = tempFile.exists();
            System.out.println(exists);
            if(exists){
                netOut.write("The file do exists");
                netOut.flush();
            } else {
                netOut.write("The file doesn't exist");
                netOut.flush();
            }


            communication.close();
        }    
    }
} 

arg [0] =通信端口

发生的事情是，服务器从不发送证明文件存在的字符串。 我在服务器中添加了一些println（），以确保从客户端到服务器的通信正常，并且似乎运行正常。