通过套接字接收文件时的数据重复

Question

Sorry for the bad English, I used Google translate.

Working on an Application that needs to transfer a file over the network with the ability to resume, the program works, but why when you open a text file transmitted through nano seen that data is duplicated.

Server

OutputStream outToClient = socket.getOutputStream();

        File myfile = new File(filePath);
        System.out.println("файл " + myfile.toString());
        byte[] mybytearray = new byte[(int) myfile.length()];
        BufferedInputStream bis = new BufferedInputStream(new FileInputStream(myfile));

        BufferedOutputStream bost = new BufferedOutputStream(new FileOutputStream(new File(filePath+"111")));
        bost.write(mybytearray, 0, mybytearray.length);
        bis.skip(filePosition);
        bis.read(mybytearray, 0, mybytearray.length);
        bost.write(mybytearray, 0, mybytearray.length);
        outToClient.write(mybytearray, 0, mybytearray.length);


        outToClient.flush();
        bis.close();

Client

 byte[] mybytearray = new byte[1024];
    fos = new FileOutputStream(fullPath, true);
    bos = new BufferedOutputStream(fos);
    InputStream is = socket.getInputStream();
    int bytesRead = is.read(mybytearray, 0, mybytearray.length);

    bos.write(mybytearray, 0, bytesRead);
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    do {
        baos.write(mybytearray);
        bytesRead = is.read(mybytearray);

        if (bytesRead != -1)
            filePosition += bytesRead;
    } while (bytesRead != -1);

    bos.write(baos.toByteArray());
    bos.close();   socket.close();

    is.close();
    socket.close();

Answer 1

You are getting some duplicate data because you are writing the same array contents to the output file twice before filling the array with new data. You are not using the streams very well. Try something more like this instead:

Server

OutputStream outToClient = socket.getOutputStream();

byte[] mybytearray = new byte[1024];
File myfile = new File(filePath);
BufferedInputStream bis = new BufferedInputStream(new FileInputStream(myfile));
bis.skip(filePosition);
do {
    int bytesRead = bis.read(mybytearray, 0, mybytearray.length);
    if (bytesRead <= 0) {
        break;
    }
    outToClient.write(mybytearray, 0, bytesRead);
}
white (true);

outToClient.flush();
bis.close();

Client

byte[] mybytearray = new byte[1024];
//todo: seek the output file to the starting filePosition
//instead of just appending to the end of the file...
fos = new FileOutputStream(fullPath, true);
bos = new BufferedOutputStream(fos);
InputStream is = socket.getInputStream();
do {
    int bytesRead = is.read(mybytearray, 0, mybytearray.length);
    if (bytesRead <= 0) {
        break;
    }
    bos.write(mybytearray, 0, bytesRead);
    filePosition += bytesRead;
} while (true);

bos.close();
is.close();
socket.close();