import com.sun.net.httpserver.HttpExchange;

import com.sun.net.httpserver.HttpHandler;

import com.sun.net.httpserver.HttpServer;

import java.io.IOException;

import java.io.OutputStream;

import java.io.PrintWriter;

import java.io.StringWriter;

import java.net.InetSocketAddress;

public class main {

  private static HttpServer server;

  private static int port = 8080;

  public static void main(String[] args) throws Exception {

    server = HttpServer.create(new InetSocketAddress(port), 0);

    createHttpContext("/", new MainContext());

    server.setExecutor(null); // creates a default executor

    server.start();

    System.out.println("HTTP server started (listening on port " + port + "!)");

  }

  private static void createHttpContext(String path, HttpHandler handler) {

    server.createContext(path, new SafeHttpHandler(handler));

  }

  public static class SafeHttpHandler implements HttpHandler {

    private HttpHandler handler;

    public SafeHttpHandler(HttpHandler handler) {

      this.handler = handler;

    }

    public void handle(HttpExchange exchange) throws IOException {

      System.out.println("[web server] Handling request: " + exchange.getRequestURI());

      try {

        handler.handle(exchange);

      } catch (Throwable e) {

        String stackTrace = getStackTrace(e);

        sendServerError(exchange, stackTrace);

        System.out.println(stackTrace);

      } finally {

        exchange.close();

        System.out.println("[web server] Done handling request: " + exchange.getRequestURI());

      }

    }

  }

  public static String getStackTrace(Throwable e) {

    StringWriter stringWriter = new StringWriter();

    e.printStackTrace(new PrintWriter(stringWriter));

    return stringWriter.toString();

  }

  public static void sendHtml(HttpExchange exchange, String content) throws IOException {

    int responseCode = 200;

    String contentType = "text/html";

    sendHttpTextResponse(exchange, responseCode, content, contentType);

  }

  public static void sendHttpTextResponse(HttpExchange exchange, int responseCode, String content, String contentType) throws IOException {

    byte[] bytes = content.getBytes("UTF-8");

    String header = contentType + "; charset=utf-8";

    System.out.println("Sending content type: " + header);

    exchange.getResponseHeaders().set("Content-Type", header);

    exchange.sendResponseHeaders(responseCode, bytes.length);

    OutputStream os = exchange.getResponseBody();

    os.write(bytes);

    os.close();

  }

  public static void sendServerError(HttpExchange exchange, String response) throws IOException {

    sendHttpTextResponse(exchange, 500, response, "text/plain");

  }

  public static class MainContext implements HttpHandler {

    public void handle(HttpExchange httpExchange) throws IOException {

      sendHtml(httpExchange, "Hello world! <a href='http://javax.tinybrain.de'>JavaX.</a>");

    }

  }

}