Hướng dẫn Updater.java - update plugin qua web

import java.io.*;

public void onEnable() {
       if(Updater.check(this.getDescription().getVersion())) {
           Bukkit.log("A new version detected v" + Updater.ver());
           if(!this.getFile().delete()) Bukkit.log("An error occured while removing old version");
           Updater.update(new File("./plugins/MyPlugin-" + Updater.ver() + ".jar"));
           Bukkit.log("Update completed");
       }
}

ver$1.0.0
url$http://my.domain.org/plugin.jar

package acayrin.updater;

import java.io.*;
import java.net.*;

public class Updater {
    protected static String toGET = "http://my.domain.org/plugin.txt";

    public static boolean check(String ver) {
        String chk = ver();
        if(ver.equals(chk)) return false;
        return true;
    }

    public static void update(File file) {
        try {
            URL link = new URL(url());
            InputStream input = link.openStream();
            if (file.exists()) {
                if (file.isDirectory())
                    throw new IOException("File '" + file + "' is a directory");

                if (!file.canWrite())
                    throw new IOException("File '" + file + "' cannot be written");
            } else {
                File parent = file.getParentFile();
                if ((parent != null) && (!parent.exists()) && (!parent.mkdirs())) {
                    throw new IOException("File '" + file + "' could not be created");
                }
            }

            FileOutputStream output = new FileOutputStream(file);

            byte[] buffer = new byte[4096];
            int n = 0;
            while (-1 != (n = input.read(buffer))) {
                output.write(buffer, 0, n);
            }

            input.close();
            output.close();
        }
        catch(IOException e) {
            e.printStackTrace();
        }
    }

    public static String ver() {
        String ver = null;
        try {
            URL url = new URL(toGET);
            URLConnection conn = url.openConnection();
            BufferedReader br = new BufferedReader(
                    new InputStreamReader(conn.getInputStream()));

            String line;
            while ((line = br.readLine()) != null) {
                if(line.contains("ver")) ver = line.replace("ver$", "");
            }
            br.close();
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return ver;
    }

    public static String url() {
        String res = null;
        try {
            URL url = new URL(toGET);
            URLConnection conn = url.openConnection();
            BufferedReader br = new BufferedReader(
                    new InputStreamReader(conn.getInputStream()));

            String line;
            while ((line = br.readLine()) != null) {
                if(line.contains("url")) res = line.replace("url$", "");
            }
            br.close();
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return res;
    }
}