Java Sockets - Hang on reading data from server

Question

I'm currently working on a little Client/Server task with using sockets. Sadly I the client hangs when it is supposed to read the "200 OK File Created" sent by the server. Is there anything i overlooked?

Client:

public HTTPClient(InetAddress adress, int portnumber, String filename) throws IOException {
    socket = new Socket(adress, portnumber);
    input = new BufferedReader(new InputStreamReader(socket.getInputStream()));
    output = new PrintWriter(socket.getOutputStream());
    this.filename = filename;
}

public void sendPutRequest() throws IOException {
    output.println("PUT /" + filename + " HTTP/1.0");
    output.flush();
    File myFile = new File(this.filename);
    if (myFile.exists()) {
        for (String string : Files.readAllLines(myFile.toPath())) {
            output.println(string);
        }
        output.flush();
        String line;
        while ((line = input.readLine()) != null) {
            System.out.println(line);
        }
    } else {
        throw new IOException("File not found");
    }
}

Server:

  try (Socket client = this.socket.accept(); 
    BufferedReader in = new BufferedReader(
    new InputStreamReader(client.getInputStream()));
    PrintWriter out = new PrintWriter(client.getOutputStream())) {

    String lineIn = in.readLine();
    if (lineIn.contains("PUT")) {
        String filename = lineIn.split(" ")[1].substring(1);
        List<String> filedata = new ArrayList<>();
        String line;
        while ((line = in.readLine()) != null) {
            filedata.add(line);
            System.out.println(line);
        }
        writeToFile(filename, filedata);
        out.println("200 OK File Created");
        out.flush();
    }
}

Answer 1

Your server is reading from the connection until it is closed (only in such a case in.readLine() will return null ).

However your client does not close the connection to the server. Therefore the server is stuck in the while loop.

Solution: You have to close the output stream after sending the request. Alternatively detect the end of the request on server side without waiting for the "end of stream" limit.

Answer 2

In your server code:

            while ((line = in.readLine()) != null) {
                filedata.add(line);
                System.out.println(line);
            }
             writeToFile(filename, filedata); // getting to this line?

Your server is never getting to the writeToFile line, because the socket connection is still open, and it's still in the while loop. As a solution, use DataFetcher