Reddit.java

import java.io.*;
import java.net.*;
import java.util.*;
import com.sun.net.httpserver.*;
public class Reddit implements Serializable {
    public String title;
    public URL url;
    public int rating;
    public int id;
    public static String htmlentities(String s) {
        return s.replace("&", "&").replace("'", "'")
        .replace("\"", "&#34;").replace("<", "&lt;").replace(">", "&gt;");
    }
    public static void printall(Formatter out, ArrayList<Reddit> reddits, Comparator<Reddit> cmp) {
        Collections.sort(reddits, cmp);
        for (Reddit reddit: reddits) {
            out.format("<li>%1$s <form style='display:inline' action='/up/%2$s' method='post'><button>↑</button></form><form style='display:inline' action='/down/%2$s' method='post'><button>↓</button></form> <a href='%3$s'>%4$s</a></li>",
                reddit.rating, reddit.id,
                Reddit.htmlentities(reddit.url.toString())
                , Reddit.htmlentities(reddit.title));
        }
    }
    public static void main(String[] args) throws Exception {
        final HttpServer server = HttpServer.create(new InetSocketAddress(8080), 42);
        server.createContext("/", new HttpHandler() {{
            try {
                new ObjectInputStream(new FileInputStream("reddit.db")) {{
                    reddits = (ArrayList<Reddit>)readObject();
                }}.close();
            } catch (final Exception e) {
                reddits = new ArrayList<Reddit>();
            }}
            ArrayList<Reddit> reddits;
            public void handle(final HttpExchange exchange) {
                try {
                    final String path = exchange.getRequestURI().getPath();
                    if (exchange.getRequestMethod().equals("POST")) {
                        exchange.getResponseHeaders().set("Location", "/");
                        if (path.matches("/up/\\d+")) {
                            exchange.sendResponseHeaders(303, -1);
                            reddits.get(Integer.parseInt(path.substring(4))).rating += 1;
                        } else if (path.matches("/down/\\d+")) {
                            exchange.sendResponseHeaders(303, -1);
                            reddits.get(Integer.parseInt(path.substring(6))).rating -= 1;
                        } else if (path.equals("/add/")) {
                            exchange.sendResponseHeaders(303, -1);
                            final char[] raw = new char[4242];
                            new Reddit() {{
                                for (String arg: new String(raw, 0,
                                    new InputStreamReader(exchange.getRequestBody()).read(raw)).split("&")) {
                                    String [] kv = arg.split("=", 2);
                                    kv[1] = URLDecoder.decode(kv[1], "UTF-8");
                                    if ("url".equals(kv[0])) {
                                        if (!kv[1].matches("http(s?)://.*")) kv[1] = "http://" + kv[1];
                                        url = new URL(kv[1]);
                                    } else if ("title".equals(kv[0])) {
                                        title = kv[1];
                                    }
                                }
                                id = reddits.size();
                                if (url != null && null != title) reddits.add(this);
                            }};
                        } else {
                            exchange.sendResponseHeaders(404, -1);
                        }
                        new ObjectOutputStream(new FileOutputStream("reddit.db")) {{
                            writeObject(reddits);
                        }}.close();
                    } else if (exchange.getRequestMethod().equals("GET")) {
                        if (path.equals("/")) {
                            exchange.getResponseHeaders().set("Content-Type", "text/html; charset=UTF-8");
                            exchange.sendResponseHeaders(200, 0);
                            new OutputStreamWriter(exchange.getResponseBody(), "UTF-8") {{
                                write("<html><head><title>Reddit</title></head><body><form action='/add/' method='post'>Url:<input name='url'> Title:<input name='title'><input type='submit'></form><h1>Best</h1><ul>");
                                final ArrayList<Reddit> r2d2 = new ArrayList<Reddit>(reddits);
                                Reddit.printall(new Formatter(this), r2d2, new Comparator<Reddit>() {
                                    public int compare(Reddit a, Reddit b) {
                                        return b.rating - a.rating;
                                }});
                                write("</ul><h1>Newest</h1><ul>");
                                Reddit.printall(new Formatter(this), r2d2, new Comparator<Reddit>() {
                                    public int compare(Reddit a, Reddit b) {
                                        return b.id - a.id;
                                }});
                                write("</ul></body></html>");
                            }}.flush();
                        } else {
                            exchange.sendResponseHeaders(404, -1);
                        }
                    } else {
                        exchange.sendResponseHeaders(500, -1);
                    }
                } catch (final Exception e) {
                    e.printStackTrace();
                } finally {
                    exchange.close();
        }}});
        System.out.println("Reddit running on 8080 !");
        server.start();
}}