JAVA 中客户端到客户端的文件传输

Question

我需要实现一个程序来传输文件。我决定使用大约 1 个月前制作的聊天模板来制作它，这样我就可以使用文件传输选项进行聊天。转移应遵循以下几点：

1- 服务器只保留连接的客户端提供的所有文件的列表（没有文件实际位于服务器中，只有它们的名称）

2- 客户端“1”请求文件 "A" 然后：

如果文件 "A" 仅位于客户端“2”中，则客户端“2”应将 100% 的文件发送给客户端“1”

如果文件 "A" 位于客户端“2”中并且客户端“3”也有文件 "A"，则客户端“2”应将文件的 50% 发送给客户端“1”客户端“3”应该发送另外 50%。

（如果该文件位于 4 个客户端中，我应该每个客户端占 25%……这样……）

我已经设法让服务器找出哪个客户端正在请求该文件以及哪个客户端拥有该文件。但是现在我卡住了，我不知道如何进行转移。

有人可以给我一个如何做的例子吗？或者指出我正确的方向？

[我知道我的代码有一些缺陷，我稍后会修复它，现在我需要在修复之前进行传输，所以请，除非它相关，否则请尝试专注于此]

服务器：

package tor;

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

public class Server extends Thread {

private String cname;
private Socket client;
public static Vector<PrintStream> clients;
public static Vector<String> clientnames;
public static Vector<String> archives;
public Server(Socket client) {
    this.client = client;

}

public static void main(String[] args) {
    clients = new Vector<PrintStream>();
    clientnames = new Vector<String>();
    archives = new Vector<String>();

    try {

        ServerSocket server = new ServerSocket(2391);
        System.out.println("Server Started!!\n");
        while (true) {
            Socket client = server.accept();
            Server s = new Server(client);
            s.start();
        }

    } catch (IOException e) {
        System.out.println("Server could not start ");

    }

}


@Override
public void run() {

    try {
        BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream()));
        PrintStream out = new PrintStream(client.getOutputStream());
        cname = in.readLine();
        System.out.println(cname + " Connected --- SERVER!");

        if (cname == null) {
            System.out.println("Unknown Name");
            return;
        }
        clientnames.add(cname);
        clients.add(out);
        connected(" ********** [", cname, "] Connected! **********");

        String arq;
        int size = in.read();
        System.out.println(size);
        for (int i = 0; i < size; i++) {
            arq = in.readLine();
            archives.add(arq);
        }
        String msg = in.readLine();
        String selected;
        while (true) {
            while (!(msg).equals("/exit") && !(msg).equals("/Exit") && !(msg).equals("/EXIT")) {

                if ((msg).equals("/list") || (msg).equals("/List") || (msg).equals("/list")) {
                    out.println("-------- Archives List --------");
                    for (int i = 0; i < archives.size(); i++) {
                        out.println(i+"- "+archives.get(i));
                    }
                    out.println("-------- ******************* --------");
                    msg = in.readLine();
                } else if (msg.equals("/get") || (msg.equals("/GET")) || (msg.equals("/Get"))){
                    msg = in.readLine();
                    int gnum = Integer.parseInt(msg);
                    selected=archives.get(gnum);
                    returnAll("[", out, "]: ", "idreq");
                    out.println("1");
                    reqAll(selected);

                    // I BELIVE HERE IS THE RIGHT PLACE TO MAKE DE TRANSFER CODE


                    msg = in.readLine();
                } else {
                    returnAll("[", out, "]: ", msg);
                    msg = in.readLine();
                }
            }
            msg = in.readLine();
            size = Integer.parseInt(msg);
            for (int i = 0; i <= size; i++) {
                arq = in.readLine();
                for(int j=0;j<archives.size();j++) {
                if (archives.get(j).equals(arq)) {
                    archives.remove(j);
                }
                }
            }
            returnAll(" ********** [", out, "] disconnected ", " ********** ");
            clients.remove(out);
            clientnames.remove(cname);
            client.close();
            break;
        }
    } catch (IOException e) {
        System.out.println("A Client disconnected ");
    }

}

// METHOD TO SEND CONNECTION MESSAGE
public void connected(String msg1, String cname, String msg2) throws IOException {
    Enumeration<PrintStream> e = clients.elements();
    while (e.hasMoreElements()) {
        PrintStream message = (PrintStream) e.nextElement();
        message.println(msg1 + cname + msg2);
    }
}

// METHOD TO RETURN MESSAGE TO ALL CLIENTS
public void returnAll(String msg1, PrintStream saida, String ac, String msg2) throws IOException {
    Enumeration<PrintStream> e = clients.elements();
    while (e.hasMoreElements()) {
        PrintStream message = (PrintStream) e.nextElement();
        message.println(msg1 + cname + ac + msg2);
    }
}

public void reqAll(String req) throws IOException {
    Enumeration<PrintStream> e = clients.elements();
    while (e.hasMoreElements()) {
        PrintStream message = (PrintStream) e.nextElement();
        message.println(req);
    }
}


}

客户：

package tor;

import java.io.*;
import java.net.*;
import java.util.ArrayList;
import java.util.Scanner;


public class Client extends Thread {
    private Socket con;
    private static boolean done = false;
    static ArrayList<String> localArq = new ArrayList<String>();
    static int c=0;

public Client(Socket s) {
    con = s;
}

public static void main(String[] args) {


    try {
        String ip;
        Scanner s = new Scanner(System.in);
        System.out.print("Enter Server's IP: ");
        ip =s.next();
        Socket con = new Socket(ip, 2391);
        PrintStream out = new PrintStream(con.getOutputStream());
        System.out.println("Connected to Server!");
        System.out.print("Enter your Nickname: ");
        BufferedReader scan = new BufferedReader(new InputStreamReader(System.in));
        String cname = scan.readLine();
        out.println(cname);
        String dir="C:\javator\"+cname;
        Thread t = new Client(con);
        t.start();

        File folder = new File(dir);
        folder.mkdir();
        File[] listOfFiles = folder.listFiles();
        for (int i = 0; i < listOfFiles.length; i++) {
          if (listOfFiles[i].isFile()) {
            localArq.add(listOfFiles[i].getName());
          }
        }
        int size=localArq.size();
        out.write(size);
        for(int i=0;i<size;i++) {
            out.println(localArq.get(i));
        }


        String msg;
        while (true) {
            System.out.print("");
            msg = scan.readLine();
            if(msg.equals("/ll")) {
            System.out.println("-------- LOCAL LIST --------");
            for (int i = 0; i < localArq.size(); i++) {
                System.out.println(localArq.get(i));
            }
            System.out.println("-------- ******************* --------");
            msg = scan.readLine();
            }else if(msg.equals("/exit") || (msg.equals("/Exit")) || (msg.equals("/EXIT"))) {
                out.println(msg);
                size=localArq.size();
                out.println(size);
                for(int i=0;i<size;i++) {
                    out.println(localArq.get(i));
                }

            }
            else if(msg.equals("/get") || (msg.equals("/GET")) || (msg.equals("/Get"))) {
                System.out.println("Chose file's number to /get: ");
            c++;
            }
            if (done == true) {
                break;
            }
            out.println(msg);
    }
    } catch (UnknownHostException e) {
        System.out.println(e.getMessage());
    } catch (IOException e) {
        System.err.println(e.getMessage());
    }
}

@Override
public void run() {
    try {
        BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
        String rmsg;
        String req;

        while (true) {
            rmsg = in.readLine();
            if (rmsg == null) {
                System.out.println("Connection Terminated");
                break;
            }else if(rmsg.substring(rmsg.length() - 5).equals("idreq")) {

                req = in.readLine();
                for(int i=0;i<localArq.size();i++) { //IDENTIFIES WHO OWNS THE REQUESTED FILE
                    if(localArq.get(i).equals(req)) {

                        System.out.println("Owns requested file");
                        Socket requester = new Socket("192.168.3.114", 2007);
                        ObjectOutputStream outputr = new ObjectOutputStream(requester.getOutputStream());
                        ObjectInputStream inputr = new ObjectInputStream(requester.getInputStream());
                        Object mens= inputr.readObject();
                        System.out.println(mens);
                        outputr.writeObject("OWNER FOUND");
                    }
                }
                if(c==1) { //IDENTIFIES WHO WANTS THE FILE
                rmsg = in.readLine();
                c= Integer.parseInt(rmsg);
                System.out.println("file: "+req);

                ServerSocket peer = new ServerSocket(2007);
                System.out.println("OPEN FOR CONNECTIONS\n");

                    Socket client = peer.accept();
                    System.out.println("Client connected: " + client.getInetAddress().getHostAddress());
                    ObjectOutputStream outputo = new ObjectOutputStream(client.getOutputStream());
                    ObjectInputStream inputo = new ObjectInputStream(client.getInputStream());
                    outputo.flush();
                    outputo.writeObject("Connected to requester");
                    Object mens= inputo.readObject();
                    System.out.println(mens);

                }

            }
             else {
            System.out.println(rmsg);
            }
        }
    } catch (IOException e) {
        e.printStackTrace();
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }
    done = true;
}
}

Answer 1

通过提供的信息和对 Whosebug 的一些研究，我能够轻松地在两个客户端之间进行传输，以了解更多关于 out/inputStreams 的信息！这个post也对我帮助很大：Sending a file with Java Sockets, losing data 下一步是共享传输

JAVA 中客户端到客户端的文件传输

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