While reading from socket how to detect when the c

问题:

I am now writing a http server and I am having problem with reading from a socket. My problem is that the inputStream from the client never ends and it keeps reading until the client is closed. I know that the client doesn't close the connection with the server immediately after sending the http request. How can I quit the while loop when client has sent all the request data (i.e. headers + body).

while (in.hasNextLine()) {
    String line = in.nextLine();

    if (line.equals("")){ // last line of request header is blank
        break; // quit while loop when last line of header is reached
    } else {
        request = request + line + "\n";
    }
}

After reading comments and answer from you guys, this is what I came up with,

     is = incoming.getInputStream();
            os = incoming.getOutputStream();
            in = new Scanner(is);
            out = new DataOutputStream(os);

            RequestHandler rh = new RequestHandler();
            int length = 0;
            while (in.hasNextLine()) {
                String line = in.nextLine();
                if (line.equals("")) { // last line of request message
                                        // header is a
                                        // blank line
                    break; // quit while loop when last line of header is
                            // reached
                }

                if (line.startsWith("Content-Length: ")) { // get the
                                                            // content-length
                    int index = line.indexOf(':') + 1;
                    String len = line.substring(index).trim();
                    length = Integer.parseInt(len);
                }

                request = request + line + "\n";
            }

             byte[] body = new byte[length];
             int i = 0;
             while (i < length) {
             byte b = in.nextByte();
             body[i] = b;
             i++;
             }

but, I still don't get it about reading by bytes. I can write my code to read until -1, but still stuck when there is no EOF and client is not closing connection.

回答1:

There are 3 ways of detecting the end of the stream depending on what requests you are handling:

1. If it is a GET or HEAD request, you only need to read the HTTP headers, request body is normally ignored if it exists, so when you encounter \r\n\r\n, you reach the end of the request(actually the request headers).
2. If it is a POST method, read the Content-Length in the header and read up to Content-Length bytes.
3. If it is a POST method and the Content-Length header is absent, which is most likely to happen, read until -1 is returned, which is the signal of EOF.

回答2:

I've got it :) Thank you guys for comments and answers...

     is = incoming.getInputStream(); // initiating inputStream
            os = incoming.getOutputStream(); // initiating outputStream

            in = new BufferedReader(new InputStreamReader(is)); // initiating
                                                                // bufferReader
            out = new DataOutputStream(os); // initiating DataOutputSteream

            RequestHandler rh = new RequestHandler(); // create a
                                                        // requestHandler
                                                        // object

            String line;
            while ((line = in.readLine()) != null) {
                if (line.equals("")) { // last line of request message
                                        // header is a
                                        // blank line (\r\n\r\n)
                    break; // quit while loop when last line of header is
                            // reached
                }

                // checking line if it has information about Content-Length
                // weather it has message body or not
                if (line.startsWith("Content-Length: ")) { // get the
                                                            // content-length
                    int index = line.indexOf(':') + 1;
                    String len = line.substring(index).trim();
                    length = Integer.parseInt(len);
                }

                request.append(line + "\n"); // append the request
            } // end of while to read headers

            // if there is Message body, go in to this loop
            if (length > 0) {
                int read;
                while ((read = in.read()) != -1) {
                    body.append((char) read);
                    if (body.length() == length)
                        break;
                }
            }

            request.append(body); // adding the body to request