帮我编写一个java程序，模拟网站下载图片的功能,先让客户端给服务器发请求,告诉服务器要下载的文件名,然后服务器就给客户端传递文件,直至传递完成; **要求:** 1:服务器使用线程池完成,每次客户请求下载文件时,就使用一个线程与客户端交互; 2:要求客户端保存文件时文件名使用UUID随机生成;

好的，我可以为您编写一个Java程序，模拟网站下载图片的功能。以下是程序的基本流程：

1. 客户端向服务器发送下载请求，请求下载指定文件名的图片。
2. 服务器接收到请求后，使用线程池创建一个线程与客户端进行交互。
3. 服务器读取指定文件名的图片，并将其传递给客户端。
4. 客户端接收到图片后，使用UUID随机生成一个文件名，并将图片保存到本地。

以下是程序的代码：

Server.java

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class Server {
    private static final int PORT = 8888;
    private static final int THREAD_POOL_SIZE = 10;

    public static void main(String[] args) {
        ExecutorService executorService = Executors.newFixedThreadPool(THREAD_POOL_SIZE);
        try (ServerSocket serverSocket = new ServerSocket(PORT)) {
            System.out.println("Server started on port " + PORT);
            while (true) {
                Socket clientSocket = serverSocket.accept();
                executorService.execute(new ClientHandler(clientSocket));
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static class ClientHandler implements Runnable {
        private final Socket clientSocket;

        public ClientHandler(Socket clientSocket) {
            this.clientSocket = clientSocket;
        }

        @Override
        public void run() {
            try (BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
                 OutputStream out = clientSocket.getOutputStream()) {
                String fileName = in.readLine();
                File file = new File(fileName);
                if (!file.exists()) {
                    out.write("File not found".getBytes());
                    return;
                }
                try (FileInputStream fileInputStream = new FileInputStream(file)) {
                    byte[] buffer = new byte[1024];
                    int bytesRead;
                    while ((bytesRead = fileInputStream.read(buffer)) != -1) {
                        out.write(buffer, 0, bytesRead);
                    }
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

Client.java

import java.io.*;
import java.net.Socket;
import java.util.UUID;

public class Client {
    private static final String SERVER_ADDRESS = "localhost";
    private static final int SERVER_PORT = 8888;

    public static void main(String[] args) {
        try (Socket socket = new Socket(SERVER_ADDRESS, SERVER_PORT);
             BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
             FileOutputStream fileOutputStream = new FileOutputStream(UUID.randomUUID().toString() + ".jpg")) {
            String fileName = "image.jpg";
            PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
            out.println(fileName);
            byte[] buffer = new byte[1024];
            int bytesRead;
            while ((bytesRead = socket.getInputStream().read(buffer)) != -1) {
                fileOutputStream.write(buffer, 0, bytesRead);
            }
            System.out.println("File downloaded successfully");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

请注意，此程序仅用于演示目的，实际应用中可能需要进行更多的错误处理和安全检查。