用java设计并实现一个基于字符界面的C/S结构的文件传输程序

好的，我可以为您提供一份基本的Java代码实现：

1. 客户端界面设计

客户端界面采用字符界面，使用Java中的Console类来实现。客户端界面需要包括以下功能：

- 连接服务器
- 上传文件
- 下载文件
- 查看服务器上的文件列表
- 断开连接

以下是客户端界面的代码实现：

import java.io.BufferedReader;
import java.io.Console;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.Socket;

public class Client {
    private Socket socket;
    private BufferedReader reader;
    private Console console;

    public Client() {
        console = System.console();
    }

    public void start() {
        while (true) {
            String command = console.readLine("请输入命令：");
            if (command.equals("connect")) {
                connect();
            } else if (command.equals("upload")) {
                upload();
            } else if (command.equals("download")) {
                download();
            } else if (command.equals("list")) {
                list();
            } else if (command.equals("disconnect")) {
                disconnect();
                break;
            } else {
                System.out.println("无效命令，请重新输入！");
            }
        }
    }

    private void connect() {
        try {
            String host = console.readLine("请输入服务器地址：");
            int port = Integer.parseInt(console.readLine("请输入服务器端口号："));
            socket = new Socket(host, port);
            reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            System.out.println("连接成功！");
        } catch (IOException e) {
            System.out.println("连接失败！");
            e.printStackTrace();
        }
    }

    private void upload() {
        // TODO: 实现文件上传
    }

    private void download() {
        // TODO: 实现文件下载
    }

    private void list() {
        // TODO: 实现查看服务器上的文件列表
    }

    private void disconnect() {
        try {
            socket.close();
            reader.close();
            System.out.println("已断开连接！");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        Client client = new Client();
        client.start();
    }
}

2. 服务器端实现

服务器端需要实现以下功能：

- 监听客户端连接请求
- 接收客户端上传的文件并保存到指定目录
- 发送指定目录下的文件列表给客户端
- 接收客户端下载的文件并发送给客户端

以下是服务器端的代码实现：

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;

public class Server {
    private ServerSocket serverSocket;
    private List<String> fileList;

    public Server(int port) {
        try {
            serverSocket = new ServerSocket(port);
            fileList = new ArrayList<>();
            System.out.println("服务器已启动，等待客户端连接...");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void start() {
        while (true) {
            try {
                Socket socket = serverSocket.accept();
                System.out.println("客户端已连接：" + socket.getInetAddress());
                new Thread(new ClientHandler(socket)).start();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    private synchronized void addFile(String filename) {
        fileList.add(filename);
    }

    private synchronized void removeFile(String filename) {
        fileList.remove(filename);
    }

    private synchronized List<String> getFileList() {
        return new ArrayList<>(fileList);
    }

    private class ClientHandler implements Runnable {
        private Socket socket;
        private BufferedReader reader;
        private PrintWriter writer;

        public ClientHandler(Socket socket) {
            try {
                this.socket = socket;
                reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                writer = new PrintWriter(new OutputStreamWriter(socket.getOutputStream()));
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void run() {
            try {
                while (true) {
                    String command = reader.readLine();
                    if (command == null) {
                        break;
                    }
                    if (command.equals("upload")) {
                        receiveFile();
                    } else if (command.equals("download")) {
                        sendFile();
                    } else if (command.equals("list")) {
                        sendFileList();
                    } else {
                        writer.println("无效命令！");
                        writer.flush();
                    }
                }
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                try {
                    socket.close();
                    reader.close();
                    writer.close();
                    System.out.println("客户端已断开连接：" + socket.getInetAddress());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

        private void receiveFile() throws IOException {
            String filename = reader.readLine();
            addFile(filename);
            FileOutputStream fos = new FileOutputStream(filename);
            byte[] buffer = new byte[1024];
            int len;
            while ((len = socket.getInputStream().read(buffer)) != -1) {
                fos.write(buffer, 0, len);
            }
            fos.close();
            removeFile(filename);
            System.out.println("已接收文件：" + filename);
        }

        private void sendFile() throws IOException {
            String filename = reader.readLine();
            File file = new File(filename);
            if (!file.exists() || !file.isFile()) {
                writer.println("文件不存在！");
                writer.flush();
                return;
            }
            FileInputStream fis = new FileInputStream(file);
            byte[] buffer = new byte[1024];
            int len;
            while ((len = fis.read(buffer)) != -1) {
                socket.getOutputStream().write(buffer, 0, len);
            }
            fis.close();
            System.out.println("已发送文件：" + filename);
        }

        private void sendFileList() throws IOException {
            List<String> fileList = getFileList();
            for (String filename : fileList) {
                writer.println(filename);
            }
            writer.flush();
            System.out.println("已发送文件列表！");
        }
    }

    public static void main(String[] args) {
        Server server = new Server(8888);
        server.start();
    }
}

以上是一个基本的Java代码实现，可以根据实际需求进行调整和优化。