HTTP server in java.java

import java.io.*;
import java.net.InetSocketAddress;
import java.net.URI;
import java.net.URLDecoder;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

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

public class main {

    public static void main(String[] args) throws Exception {
        HttpServer server = HttpServer.create(new InetSocketAddress(8000), 0);
        server.createContext("/test", new MyHandler());
        server.createContext("/get", new EchoGetHandler());
        server.createContext("/post",new EchoPostHandler());
        server.setExecutor(null); // creates a default executor
        server.start();
    }

    static class MyHandler implements HttpHandler {
        @Override
        public void handle(HttpExchange t) throws IOException {
            String response = "This is the response";
            t.sendResponseHeaders(200, response.length());
            OutputStream os = t.getResponseBody();
            os.write(response.getBytes());
            os.close();
        }
    }
    static class EchoPostHandler implements HttpHandler {

        @Override

        public void handle(HttpExchange he) throws IOException {
            // parse request
            Map<String, Object> parameters = new HashMap<String, Object>();
            InputStreamReader isr = new InputStreamReader(he.getRequestBody(), "utf-8");
            BufferedReader br = new BufferedReader(isr);
            String query = br.readLine();
            parseQuery(query, parameters);

            // send response
            String response = "";
            for (String key : parameters.keySet())
                response += key + " = " + parameters.get(key) + "\n";
            he.sendResponseHeaders(200, response.length());
            OutputStream os = he.getResponseBody();
            os.write(response.toString().getBytes());
            os.close();
        }
    }
    public static void parseQuery(String query, Map<String,
            Object> parameters) throws UnsupportedEncodingException {

        if (query != null) {
            String pairs[] = query.split("[&]");
            for (String pair : pairs) {
                String param[] = pair.split("[=]");
                String key = null;
                String value = null;
                if (param.length > 0) {
                    key = URLDecoder.decode(param[0],
                            System.getProperty("file.encoding"));
                }

                if (param.length > 1) {
                    value = URLDecoder.decode(param[1],
                            System.getProperty("file.encoding"));
                }

                if (parameters.containsKey(key)) {
                    Object obj = parameters.get(key);
                    if (obj instanceof List<?>) {
                        List<String> values = (List<String>) obj;
                        values.add(value);

                    } else if (obj instanceof String) {
                        List<String> values = new ArrayList<String>();
                        values.add((String) obj);
                        values.add(value);
                        parameters.put(key, values);
                    }
                } else {
                    parameters.put(key, value);
                }
            }
        }
    }

    static class EchoGetHandler implements HttpHandler {

        @Override

        public void handle(HttpExchange he) throws IOException {
            // parse request
            Map<String, Object> parameters = new HashMap<String, Object>();
            URI requestedUri = he.getRequestURI();
            String query = requestedUri.getRawQuery();
            parseQuery(query, parameters);

            // send response
            String response = "";
            for (String key : parameters.keySet())
                response += key + " = " + parameters.get(key) + "\n";
            he.sendResponseHeaders(200, response.length());
            OutputStream os = he.getResponseBody();
            os.write(response.toString().getBytes());
        }

    }

}