Java：将文件从服务器传输到客户端以及从客户端传输到服务器

Question

我是一个新手，我想完成从服务器到客户端的文件传输“用它做点什么”，然后将文件发送回服务器。我使用的最基本的代码在这里：

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class Main {
  public static void main(String[] args) throws IOException {
    ServerSocket servsock = new ServerSocket(123456);
    File myFile = new File("s.pdf");
    while (true) {
      Socket sock = servsock.accept();
      byte[] mybytearray = new byte[(int) myFile.length()];
      BufferedInputStream bis = new BufferedInputStream(new FileInputStream(myFile));
      bis.read(mybytearray, 0, mybytearray.length);
      OutputStream os = sock.getOutputStream();
      os.write(mybytearray, 0, mybytearray.length);
      os.flush();
      sock.close();
    }
  }
}

The client module

import java.io.BufferedOutputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.Socket;

public class Main {
  public static void main(String[] argv) throws Exception {
    Socket sock = new Socket("127.0.0.1", 123456);
    byte[] mybytearray = new byte[1024];
    InputStream is = sock.getInputStream();
    FileOutputStream fos = new FileOutputStream("s.pdf");
    BufferedOutputStream bos = new BufferedOutputStream(fos);
    int bytesRead = is.read(mybytearray, 0, mybytearray.length);
    bos.write(mybytearray, 0, bytesRead);
    bos.close();
    sock.close();
  }
} 

从这个网站得到它：http://www.java2s.com/Code/Java/Network-Protocol/TransferafileviaSocket.htm

我了解这是如何工作的，但我不知道如何将文件发送回服务器。 请帮忙。

Answer 1

我过去写过一个文件传输类，你可以在你的客户端和服务器中使用它（通过创建一个实例），并使用这些方法发送和接收文件。

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

public class FileTransferProcessor {
    Socket socket;
    InputStream is;
    FileOutputStream fos;
    BufferedOutputStream bos;
    int bufferSize;


    FileTransferProcessor(Socket client) {
        socket = client;
        is = null;
        fos = null;
        bos = null;
        bufferSize = 0;

    }

    void receiveFile(String fileName) {
        try {
            is = socket.getInputStream();
            bufferSize = socket.getReceiveBufferSize();
            System.out.println("Buffer size: " + bufferSize);
            fos = new FileOutputStream(fileName);
            bos = new BufferedOutputStream(fos);
            byte[] bytes = new byte[bufferSize];
            int count;
            while ((count = is.read(bytes)) >= 0) {
                bos.write(bytes, 0, count);
            }
            bos.close();
            is.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    void sendFile(File file) {

        FileInputStream fis;
        BufferedInputStream bis;
        BufferedOutputStream out;
        byte[] buffer = new byte[8192];
        try {
            fis = new FileInputStream(file);
            bis = new BufferedInputStream(fis);
            out = new BufferedOutputStream(socket.getOutputStream());
            int count;
            while ((count = bis.read(buffer)) > 0) {
                out.write(buffer, 0, count);

            }
            out.close();
            fis.close();
            bis.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}