MV autoupdates Appengine API

EMF.java

package com.onarandombox.mvapi;

import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;

public final class EMF {
    private static final EntityManagerFactory emfInstance =
        Persistence.createEntityManagerFactory("transactions-optional");

    private EMF() {}

    public static EntityManagerFactory get() {
        return emfInstance;
    }
}

LatestServlet.java

package com.onarandombox.mvapi;

import java.io.IOException;

import javax.persistence.EntityManager;
import javax.servlet.http.*;

@SuppressWarnings("serial")
public class LatestServlet extends HttpServlet {
    @Override
    public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        resp.setContentType("text/plain");

        String name = req.getParameter("name");
        if ((name == null) || name.equals("")) {
            resp.getWriter().println("No name given!");
            resp.setStatus(400);
            return;
        }

        System.out.println("Checking for name: " + name);

        EntityManager em = EMF.get().createEntityManager();
        try {
            PluginEntry entry = em.find(PluginEntry.class, name);
            if (entry == null) {
                // wtf
                resp.getWriter().println(String.format("No entry for plugin '%s'!", name));
                System.out.println("Doesn't contain " + name);
                resp.setStatus(400);
            } else {
                String response = entry.getLatestResponse();
                System.out.println("Responding:");
                System.out.println(response);
                resp.getWriter().println(response);
            }
        } finally {
            em.close();
        }
    }
}

PluginEntry.java

package com.onarandombox.mvapi;

import javax.persistence.Basic;
import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class PluginEntry {
    private static final String VERSION_KEY = "version";
    private static final String URL_KEY = "updateUrl";

    @Id
    private String pluginName;
    @Basic(optional = false)
    private String versionString;
    @Basic(optional = false)
    private String downloadUrl;

    @Basic(optional = true)
    private String latestResponse;

    public PluginEntry(String pluginName, String versionString, String downloadUrl) {
        this.pluginName = pluginName;
        this.versionString = versionString;
        this.downloadUrl = downloadUrl;
    }

    public String getPluginName() {
        return pluginName;
    }

    public String getVersionString() {
        return versionString;
    }

    public String getDownloadUrl() {
        return downloadUrl;
    }

    public String getLatestResponse() {
        // build lazily
        if (latestResponse == null) {
            StringBuilder sb = new StringBuilder();
            sb.append(VERSION_KEY).append(": ").append(versionString).append('\n');
            sb.append(URL_KEY).append(": ").append(downloadUrl).append('\n');
            latestResponse = sb.toString();
        }

        return latestResponse;
    }
}

PushCoreUpdateServlet.java

package com.onarandombox.mvapi;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.persistence.EntityManager;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@SuppressWarnings("serial")
public class PushCoreUpdateServlet extends HttpServlet {
    private static final String JENKINS = "http://ci.onarandombox.com/job/Multiverse-Core/lastSuccessfulBuild/";

    private static final Pattern BUILD_NUMBER = Pattern.compile(".*#(\\d+).*");//".*Multiverse-Core #(\\d*).*");
    private static final Pattern VERSION = Pattern.compile(".*Multiverse-Core-(.*)\\.jar.*");

    @Override
    public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        resp.setContentType("text/plain");

        // just look it up from jenkins
        URL url = new URL(JENKINS);
        BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream()));

        StringBuilder pageBuilder = new StringBuilder();
        String line;
        while ((line = reader.readLine()) != null) {
            pageBuilder.append(line); //.append('\n');
        }
        reader.close();

        String page = pageBuilder.toString();
        System.out.println("Page");
        System.out.println(page);

        Matcher buildMatcher = BUILD_NUMBER.matcher(page);
        buildMatcher.matches();
        int build = Integer.parseInt(buildMatcher.group(1));
        Matcher versionMatcher = VERSION.matcher(page);
        versionMatcher.matches();
        String version = versionMatcher.group(1);

        String versionString = String.format("%s-b%d", version, build);
        String downloadUrl = String.format("http://ci.onarandombox.com/job/Multiverse-Core/" +
                        "lastSuccessfulBuild/artifact/target/Multiverse-Core-%s.jar", version);

        EntityManager entityManager = EMF.get().createEntityManager();
        try {
            entityManager.persist(new PluginEntry("Multiverse-Core", versionString, downloadUrl));
        } finally {
            entityManager.close();
        }
    };
}