when transferring files they get corrupted with java sockets

Question

I was playing around with Java sockets and I was trying to trasnfer files from a server to client, however, when they get transfer they are corrupted. This is the code from the server:

DataInputStream input;
DataOutputStream ouput;
//these two variable are initialized somewhere else in the code.
private void downloadFile() {
    try {
        String fileName= input.readUTF();
        File f = new File(path + fileName);
        size= f.length();
        file= new FileInputStream(path+ fileName);
        ouput.writeLong(size);
        byte[] buffer = new byte[1024];
        int len;
        while ((len = file.read(buffer)) > 0) {
            output.write(buffer, 0, len);
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

on the client side:

public void downloadFile(String fileName) {
    try {
        this.client= new Socket(ip,port);
        DataInputStream input= new DataInputStream(this.client.getInputStream());
        DataOutputStream ouput= new DataOutputStream(this.client.getOutputStream());

        output.writeUTF("DOWNLOAD");
        output.writeUTF(fileName);

        File f = new File(path+ fileName);
        file = new FileOutputStream(f);
        byte[] buffer = new byte[1024];
        int len;
        while ((len = input.read(buffer)) > 0) {
            file.write(buffer, 0, len);
        }
        file.flush();
        file.close();
        this.client.close();
    } catch (Exception e) {
        System.out.println("something went wrong");
    }
}

I dont know what am I doing wrong, the file gets completely transfer but not correctly.

score 3 · Accepted Answer · answered Nov 20 '11 at 06:34

3

on the server:

ouput.writeLong(size);

you dont seem to handle this on the client side, you just append it to the downloaded file as if it was part of the binary data.

answered Nov 20 '11 at 06:34

yurib

8,043
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score 1 · Answer 2 · answered Nov 20 '11 at 06:37

1

It looks like you send the length of the file from the server to the client:

    ouput.writeLong(size);

but your client code never does anything with the transmitted size, so it takes up the first few bytes of the file.

answered Nov 20 '11 at 06:37

sarnold

102,305
22
181
238

when transferring files they get corrupted with java sockets

2 Answers2