文件传输中的数据丢失 - JAVA？

Question

我有一个FileServer和一个FileClient,服务器在客户端连接时发送文件.这是一个简单的程序,只是为了理解背后的概念.

我能够将文件从服务器发送到客户端,缓冲区为1024.问题是收到的文件总是比原始文件少大约0.01 MB.因此mp3文件丢失了一些信息,而视频文件却没有玩.

我在服务器和客户端的while循环中放了一些prinln语句.我发现我的服务器没有发送整个文件.

  //Server
  byte [] mybytearray  = new byte [1024];    
  FileInputStream fis = new FileInputStream(myFile);
  BufferedInputStream bis = new BufferedInputStream(fis);
  bis.read(mybytearray,0,mybytearray.length);
  OutputStream os = sock.getOutputStream();
  System.out.println("Sending...\n mybytearray length:"+mybytearray.length+"file   length:"+(int)myFile.length());
  int read, readTotal=0;
  while ((read = fis.read(mybytearray,0,mybytearray.length)) != -1) { 

      os.write(mybytearray, 0, read);
      System.out.println("File REad:"+read+"readtotal:"+readTotal); //*
      readTotal += read;
}
  System.out.println("Final File Read:"+read+" Final readtotal:"+readTotal);
  os.flush();
  sock.close();
  } 

Println语句输出为:

Sending...
mybytearray length:1024file length:12767554
File REad:1024readtotal:0
File REad:1024readtotal:1024
.............and a lot of it...and then
File REad:1024readtotal:12756992
File REad:1024readtotal:12758016
File REad:322readtotal:12759040
Final File Read:-1 Final readtotal:12759362

文件长度:12767554&Last readTotal:12759362 shud相等.我不明白为什么最后一个读数值较低[322],而它仍然可以有1024.

任何形式的帮助都值得赞赏.谢谢.

[编辑]

//Client
int read;
int totalRead = 0;

while ((read = is.read(mybytearray,0,mybytearray.length)) != -1) {
        bos.write(mybytearray, 0 , read);

        totalRead += read;
        System.out.println("\nread:"+read+"\ntotalread: "+totalRead);
}
System.out.println("Final File Read:"+read+" Final readtotal:"+totalRead);
bos.write(mybytearray, 0 , read);  //57 Line in FileClient.java
bos.flush();

我再次尝试发送文件.这次是一个txt.这是我服务器的输出

Sending...
mybytearray length:1024file length:1232
File REad:1024readtotal:0
File REad:208readtotal:1024
Final File Read:-1 Final readtotal:1232

这个客户端

read:208
totalread: 1232
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException
   Final File Read:-1     Final readtotal:1232

at java.lang.System.arraycopy(Native Method)
at java.io.BufferedOutputStream.write(Unknown Source)
at FileClient.main(FileClient.java:57)

readtotal值是相同的,但有时我得到这个错误,有时我没有.

[大编辑 - 完整的客户代码]

public class FileClient{
 public static void main (String [] args ) throws IOException {

long start = System.currentTimeMillis();
int bytesRead;
int current = 0;
final JFrame f = new JFrame("Sample");
f.getContentPane().setLayout(new FlowLayout());
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setSize(590,490);
f.setVisible(true);
// localhost for testing
Socket sock = new Socket("localhost",13267);
System.out.println("Connecting...");
File f1=new File(RecieveObject(sock));


// receive file
byte [] mybytearray  = new byte [1024];
InputStream is = sock.getInputStream();


FileOutputStream fos = new FileOutputStream(f1);
ProgressMonitorInputStream nn= new ProgressMonitorInputStream(f,"reading",is);
BufferedOutputStream bos = new BufferedOutputStream(fos);
 /*   bytesRead = is.read(mybytearray,0,mybytearray.length);
current = bytesRead;


do {
   bytesRead =
      is.read(mybytearray, current, (mybytearray.length-current));
   System.out.println("mybytesarray length: "+mybytearray.length+"\ncurrent:"+current+"\nbytesread: "+bytesRead);
   if(bytesRead >= 0) current += bytesRead;
} while(bytesRead > -1);

bos.write(mybytearray, 0 , current);
bos.flush();
 */
int read;
int totalRead = 0;
//InputStream clientInputStream = clientSocket.getInputStream();
while ((read = is.read(mybytearray,0,mybytearray.length)) != -1) {
        bos.write(mybytearray, 0 , read);

        totalRead += read;
        System.out.println("\nread:"+read+"\ntotalread: "+totalRead);
}
System.out.println("Final File Read:"+read+" Final readtotal:"+totalRead);
 //   bos.write(mybytearray, 0 , read);
bos.flush();
long end = System.currentTimeMillis();
System.out.println(end-start);
bos.close();
sock.close();

}
public static  String RecieveObject(Socket s) {
    String str = null;
    try{
    ObjectInputStream is = new ObjectInputStream(s.getInputStream());



            str =(String)is.readUTF();


    }
    catch(IOException ex){}
    return str;
}   

}

Answer 1

由于你的第5行(包括评论),你错过了文件的开头(最多1024个字节).您从输入中读取并将其提前,而不将其发送到客户端.删除这个:

bis.read(mybytearray,0,mybytearray.length);

此外,您没有BufferedInputStream在循环中使用它.要么bis.read在这里使用而不是fis.read(如果你仍然需要缓冲读取) - 或者BufferedInputStream一起删除所有.

你的另一个问题是你正在读取客户端上的最后一个字节,然后再次进入循环.is.read再次被称为.而不是返回-1,它正在抛出一个,IOException因为套接字的另一侧已经关闭.因此,不会调用bos.flush()和bos.close(),并且您的最终字节永远不会写入磁盘.要做到这一点,请sock.shutdownOutput在关闭之前尝试打电话.无论如何,你需要在此周围添加一些适当的异常处理.