views:

310

answers:

2

i try to write simplest possible server app in Java, displaying html form with textarea input, which after submitting gives me possibility to parse xml typed in that textarea. For now i build simple serversocket based server like that:

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

public class WebServer {

  protected void start() {
    ServerSocket s;
    String gets = "";
    System.out.println("Start on port 80");
    try {
      // create the main server socket
      s = new ServerSocket(80);
    } catch (Exception e) {
      System.out.println("Error: " + e);
      return;
    }

    System.out.println("Waiting for connection");
    for (;;) {
      try {
        // wait for a connection
        Socket remote = s.accept();
        // remote is now the connected socket
        System.out.println("Connection, sending data.");
        BufferedReader in = new BufferedReader(new InputStreamReader(
            remote.getInputStream()));
        PrintWriter out = new PrintWriter(remote.getOutputStream());

        String str = ".";

        while (!str.equals("")) {
          str = in.readLine();
          if (str.contains("GET")){
            gets = str;
            break;
          }
        }

        out.println("HTTP/1.0 200 OK");
        out.println("Content-Type: text/html");
        out.println("");
        // Send the HTML page
        String method = "get";
        out.print("<html><form method="+method+">");
        out.print("<textarea name=we></textarea></br>");
        out.print("<input type=text name=a><input type=submit></form></html>");
        out.println(gets);
        out.flush();

        remote.close();
      } catch (Exception e) {
        System.out.println("Error: " + e);
      }
    }
  }

  public static void main(String args[]) {
    WebServer ws = new WebServer();
    ws.start();
  }
}

After form (textarea with xml and one additional text input) is submitted in 'gets' String-type variable I have Urlencoded values of my variables (also displayed on the screen, it looks like that:

gets = GET /?we=%3Cnetwork+ip_addr%3D%2210.0.0.0%2F8%22+save_ip%3D%22true%22%3E%0D%0A%3Csubnet+interf_used%3D%22200%22+name%3D%22lan1%22+%2F%3E%0D%0A%3Csubnet+interf_used%3D%22254%22+name%3D%22lan2%22+%2F%3E%0D%0A%3C%2Fnetwork%3E&a=fooBar HTTP/1.1 

What can i do to change GET to POST method (if i simply change it in form and than put " if (str.contains("POST")){" it gives me string like

gets = POST / HTTP/1.1

with no variables. And after that, how i can use xml from my textarea field (called 'we')?

+1  A: 

POST data is not in the first line. Print all lines and you'll see. It's actually immediately after a blank line.

irreputable
ok, but how can i pront everything if i have 'while (!str.equals("")) {' statement? Ignore the first blank line and stop on another?
MichalBE
+1  A: 

A typical HTTP POST request looks like this:

POST / HTTP/1.1
Host: www.example.com
Accept: text/html,*/*;q=0.5
User-Agent: BrowserName/1.0
Referer: http://www.example.com/
Content-type: application/x-www-form-urlencoded; charset=utf-8

foo=1&bar=2

The first line contains the method (typically GET or POST, but there's more, like HEAD, PUT, DELETE), the request URI, and the protocol version. Then there are a number of request headers, which may not be so important for a simple server. If the method is one that takes a request body (POST and PUT), then after the headers there's a blank line followed by the request body. In the case of a POST from an HTML form, the body will consists of key=value pairs for all form elements, joined by &. The values will be %-encoded.

You just need to take care of properly parsing the entire request.

You should be aware that line endings in HTTP are supposed to be Windows-style (\r\n). The readline() method might interpret this as two linebreaks, so it might look like there's an empty line between each of the real lines.

cygri
ok, but how to get to that data when my while stops on first empty line?
MichalBE
Rewrite your while loop so that it doesn't stop on the first line. Do you need help with that?
cygri