Tuesday, October 9, 2012

HttpServer - The Oracle JDK 1.6 Hidden Feature

I have seen this class many a times, but never encountered a scenario to use it. Recently in one of my application I needed to embedded a HTTP server. So I thought, Why not give this class a try !!

HTTP server infrastructure/framework is very simple to implement and is bundled only with the Oracle JDK 1.6. Following are the main classes:
  1. HttpServer
  2. HttpContext
  3. HttpExchange
See this link for sun.* package discussions.

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.InetSocketAddress;
import java.net.URLDecoder;
import java.util.List;
import java.util.concurrent.Executors;

import com.sun.net.httpserver.Headers;
import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpHandler;
import com.sun.net.httpserver.HttpServer;

public class JavaServer 
{
 public static final String nl = System.getProperty("line.separator");

 public static void main(String[] args) throws Exception 
 {
  if(args.length != 2)
  {
   printUsage();
   System.exit(-1);
  }
  String strPort = null;
  String strAddress = null;

  for (int i = 0; i < args.length; i++) 
  {
   if(args[i].startsWith("-p")){
    strPort = args[i].substring(2, args[i].length()).trim();
   }else if(args[i].startsWith("-a")){
    strAddress = args[i].substring(2, args[i].length()).trim();
   }else
    throw new IllegalArgumentException("Unknown command '" + args[i]+ "'");
  }

  if(strAddress.length() == 0 || strPort.length() == 0)
   throw new IllegalArgumentException("Port = " + strPort + ", IP = " + strAddress);

  int port = Integer.parseInt(strPort);
  InetSocketAddress address = new InetSocketAddress(strAddress, port);

  System.out.println("Going to run server on '" + address + "'");

  new JavaServer().start(address);
 }

 private static void printUsage() {
  System.out.println("$JavaServer -p<Port> -a<IP Address>");
 }

 private HttpServer server;

 public void start(InetSocketAddress address) throws IOException
 {
  server = HttpServer.create(address, 0); 
  server.setExecutor(Executors.newCachedThreadPool());
  server.createContext("/", new RootHandler());
  server.start();
 }
}

class RootHandler implements HttpHandler 
{
 private static final int BUFFER_SIZE = 1024;

 public void handle(HttpExchange exchange) throws IOException
 {
  String method = exchange.getRequestMethod();

  if(method.equalsIgnoreCase("get"))
  {
   String request = "";
   ByteArrayOutputStream baos = new ByteArrayOutputStream(BUFFER_SIZE);
   InputStream is = exchange.getRequestBody();

   byte[] buff = new byte[BUFFER_SIZE];
   while (true) 
   {
    int out = is.read(buff);
    if(out == -1)
     break;
    baos.write(buff, 0, out);
   }

   is.close();

   if (baos.size() > 0) {
    request = URLDecoder.decode(baos.toByteArray().toString(), "UTF-8");
   } else {
    request = null;
   }

   StringBuilder buf = new StringBuilder();
   buf.append("<html><head><title>Simple HTTP Server !!</title></head><body>");
   buf.append("<p><pre>");
   buf.append(exchange.getRequestMethod() + " " + exchange.getRequestURI() + " " + exchange.getProtocol() + JavaServer.nl);

   Headers headers = exchange.getRequestHeaders();

   for (String name : headers.keySet()) {
    List<String> values = headers.get(name);
    for (String value : values) {
     buf.append(name + " --> " + value + JavaServer.nl);
    }
   }
   if (request != null) {
    buf.append(JavaServer.nl);
    buf.append(request);
   }

   buf.append("</pre></p>");
   buf.append("</body></html>\n");

   String response = buf.toString();

   Headers responseHeaders = exchange.getResponseHeaders();
   responseHeaders.set("Content-Type", "text/html");
   exchange.sendResponseHeaders(HttpURLConnection.HTTP_OK, response.length());

   OutputStream res = exchange.getResponseBody();
   res.write(response.getBytes());
   res.close();
  }else
  {
   String response = "Bad request method !!";
   exchange.sendResponseHeaders(HttpURLConnection.HTTP_BAD_METHOD, response.length());
   OutputStream res = exchange.getResponseBody();
   res.write(response.getBytes());

   res.close();
  }
  exchange.close();
 }
}

Steps to run the above code

  1. Compile it using Oracle JDK 1.6
  2. Then execute this command on console (without quotes) 'Java JavaServer -p<port number> -a<ipaddress or localhost>' . For example, java JavaServer  -p5463 -a127.0.0.1
  3. Open your browser and type the URL. For example, http://127.0.0.1:5463/

You should see something like this (depends on the browser):