CODEWITHSUNDEEP
javafilesocketssend
Marcelo
Marcelo

Reputation: 1

Error sending file through java socket

I have a problem sending files through socket java. Sometimes the code works, sometimes not. I test the while block in both, it seems the code is sending all the bytes, but the server is not receiving (but even in this test, the file is sent correctly). In this case, the server stopped receive data. All files are about 150Kb. I'm using the port 9191.

Server:

while (true) {
        try {
            Socket socket = ss.accept();
            ObjectInputStream in = new ObjectInputStream(socket.getInputStream());
            String fileName = in.readUTF();

            FileOutputStream fos = new FileOutputStream(destinationPath + fileName);
            byte[] buf = new byte[1024];

            int len;
            while ((len = in.read(buf)) >= 0) {
                fos.write(buf, 0, len);
            }
            fos.flush();

        } catch (Exception ex) {
            ex.printStackTrace();
        }
}

Client: 

    try {
        Socket socket = new Socket(host, port);
        ObjectOutputStream out = new ObjectOutputStream(socket.getOutputStream());

        out.writeUTF(file.getName());
        out.writeLong(file.length());
        FileInputStream in = new FileInputStream(file);
        byte[] buf = new byte[1024];

        int len;
        while ((len = in.read(buf)) >= 0) {
            out.write(buf, 0, len);
        }

        out.close();
        socket.close();

    } catch (Exception e) {
        throw e;
    }

Upvotes: 0

Views: 605

Answers (2)

Elliott Frisch
Elliott Frisch

Reputation: 201409

On the client you say,

out.writeUTF(file.getName());
out.writeLong(file.length());

But on the server you say,

String fileName = in.readUTF();
FileOutputStream fos = new FileOutputStream(destinationPath + fileName);
byte[] buf = new byte[1024];
int len;
while ((len = in.read(buf)) >= 0) {
    fos.write(buf, 0, len);
}
fos.flush();

You didn't read the file length. And you need to make sure you read all of the sent bytes (or your file will be corrupt). Also, don't forget to close() the FileOutputStream (or use a try-with-resources to close it for you). Something like,

String fileName = in.readUTF();
try (FileOutputStream fos = new FileOutputStream(destinationPath
        + fileName)) {
    long size = in.readLong();
    byte[] buf = new byte[1024];
    long total = 0;
    int len;
    while ((len = in.read(buf)) >= 0) {
        fos.write(buf, 0, len);
        total += len;
    }
    if (total != size) {
        System.err.printf("Expected %d bytes, but received %d bytes%n",
                size, total);
    }
}

Upvotes: 1

Smith_61
Smith_61

Reputation: 2088

First you should replace ObjectInputStream and ObjectOutputStream with DataInputStream and DataOutputStream respectively. You are not serializing java objects and it makes no sense to use stream classes meant for that purpose.

Second you are sending the file length in the client but not specifically reading it in the server. It is instead getting added to the beginning of the file.

Upvotes: 1

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