Java tutorial
/* * ConnectBot: simple, powerful, open-source SSH client for Android * Copyright 2007 Kenny Root, Jeffrey Sharkey * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.connectbot.util; import java.io.ByteArrayOutputStream; import java.io.InputStream; import java.net.URL; import java.net.URLConnection; import java.util.Locale; import org.connectbot.R; import org.json.JSONObject; import android.app.AlertDialog; import android.content.Context; import android.content.DialogInterface; import android.content.Intent; import android.content.SharedPreferences; import android.content.SharedPreferences.Editor; import android.content.pm.PackageInfo; import android.content.pm.PackageManager; import android.net.Uri; import android.os.Handler; import android.os.Message; import android.preference.PreferenceManager; import android.util.Log; /** * Helper class that checks for updates to this application. On construction, it * spawns a background thread that checks for any app updates. If available, * shows a dialog to the user, prompting them to visit Market for the upgrade. * * <b>Be sure to change the UPDATE_URL field before using this class.</b> Then * place a text file at that URL containing JSON data in the format: * * <code>{"versionCode": 110, "features": "Brand new interface with over * 9,000 improvements.", "target": "search?q=searchterms"}</code> * * Which should contain information about your newest version. The * <code>target</code> field is used to build an Intent that launches Market on * the device, simply be prefixing it with <code>market://</code>. If you know * your exact Market ID, you could use the value * <code>details?id=yourexactmarketid</code> * * If you're looking for an advanced version-checking system that offers more * customization, check out Veecheck: http://www.tomgibara.com/android/veecheck/ * * @author jsharkey */ public final class UpdateHelper implements Runnable { public final static String TAG = "ConnectBot.UpdateHelper"; public final static String UPDATE_URL = "http://connectbot.org/version"; protected Context context; private String packageName, versionName; protected int versionCode; private String userAgent; /** * Constructor will automatically spawn thread to check for updates. * Recommended usage is <code>new UpdateHelper(this);</code> in the first * onCreate() of your app. */ public UpdateHelper(Context context) { this.context = context; try { // read current version information about this package PackageManager manager = context.getPackageManager(); PackageInfo info = manager.getPackageInfo(context.getPackageName(), 0); this.packageName = info.packageName; this.versionCode = info.versionCode; this.versionName = info.versionName; } catch (Exception e) { Log.e(TAG, "Couldn't find package information in PackageManager", e); return; } // decide if we really need to check for update SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context); String frequency; try { frequency = prefs.getString(PreferenceConstants.UPDATE, PreferenceConstants.UPDATE_DAILY); } catch (ClassCastException cce) { // Hm, somehow we got a long in there in the previous upgrades. frequency = PreferenceConstants.UPDATE_DAILY; Editor editor = prefs.edit(); editor.putString(PreferenceConstants.UPDATE, frequency); editor.commit(); } long lastChecked = prefs.getLong(PreferenceConstants.LAST_CHECKED, 0); long now = (System.currentTimeMillis() / 1000); long passed = now - lastChecked; boolean shouldCheck = false; if (PreferenceConstants.UPDATE_DAILY.equals(frequency)) { shouldCheck = (passed > 60 * 60 * 24); } else if (PreferenceConstants.UPDATE_WEEKLY.equals(frequency)) { shouldCheck = (passed > 60 * 60 * 24 * 7); } // place version information in user-agent string to be used later userAgent = String.format("%s/%s (%d, freq=%s, lang=%s)", packageName, versionName, versionCode, frequency, Locale.getDefault().getLanguage()); if (shouldCheck) { // spawn thread to check for update // Note that this class should be marked final because a thread is started in the constructor. Thread updateThread = new Thread(this); updateThread.setName("UpdateHelper"); updateThread.start(); // update our last-checked time Editor editor = prefs.edit(); editor.putLong(PreferenceConstants.LAST_CHECKED, now); editor.commit(); } } public void run() { try { // fetch and parse the version update information as json // pass information off to handler to create JSONObject json = new JSONObject(UpdateHelper.getUrl(UPDATE_URL, userAgent)); Message.obtain(versionHandler, -1, json).sendToTarget(); } catch (Exception e) { Log.e(TAG, "Problem while fetching/parsing update response", e); } } /** * Handler that will parse the JSON response and show dialog to user if an * update is available. */ private Handler versionHandler = new Handler() { @Override public void handleMessage(Message msg) { // make sure we are being passed a real json object if (!(msg.obj instanceof JSONObject)) return; JSONObject json = (JSONObject) msg.obj; // pull out version and target information from response final int versionCode = json.optInt("versionCode"); final String features = json.optString("features"); final String target = "market://" + json.optString("target"); // skip if we're already good enough if (versionCode <= UpdateHelper.this.versionCode) return; // build dialog to prompt user about updating new AlertDialog.Builder(context).setTitle(R.string.upgrade).setMessage(features) .setPositiveButton(R.string.upgrade_pos, new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(target)); context.startActivity(intent); } }).setNegativeButton(R.string.upgrade_neg, null).create().show(); } }; /** * Read contents of a URL and return as a String. Handles any server * downtime with a 6-second timeout. */ private static String getUrl(String tryUrl, String userAgent) throws Exception { URL url = new URL(tryUrl); URLConnection connection = url.openConnection(); connection.setConnectTimeout(6000); connection.setReadTimeout(6000); connection.setRequestProperty("User-Agent", userAgent); connection.connect(); InputStream is = connection.getInputStream(); ByteArrayOutputStream os = new ByteArrayOutputStream(); int bytesRead; byte[] buffer = new byte[1024]; while ((bytesRead = is.read(buffer)) != -1) { os.write(buffer, 0, bytesRead); } os.flush(); os.close(); is.close(); return new String(os.toByteArray()); } }