轻松实现APP自动检测更新

概述：为了以快速并且节约的方式让APP更新版本，通常需要在APP内增加自动检测更新新版本的功能。

运行截图：

       

实现：4个步骤

1.在服务端放置存储版本信息的文件

  一般以json格式保存必要的信息：apk文件下载地址、版本号、更新内容

{  "url":"http://crazyfzw.github.io/demo/auto-update-version/new-version-v2.0.apk",  "versionCode":2,  "updateMessage":"[1]新增视频弹幕功能<br/>[2]优化离线缓存功能<br/>[3]增强了稳定性"}

2.继承AsyncTask创建一个异步任务去下载版本信息文件

 从服务器取得版本信息，与本地apk对比版本号，判断是否有更新，若有，则以Dialog让用户选择是否更新，若用户选择更新，则调用服务去完成apk文件的下载

CheckVersionInfoTask.java

/** *  */public class CheckVersionInfoTask extends AsyncTask<Void, Void, String> {    private static final String TAG = "CheckVersionInfoTask";    private ProgressDialog dialog;    private Context mContext;    private boolean mShowProgressDialog;    private static final String VERSION_INFO_URL = "http://crazyfzw.github.io/demo/auto-update-version/update.json";    public CheckVersionInfoTask(Context context, boolean showProgressDialog) {        this.mContext = context;        this.mShowProgressDialog = showProgressDialog;    }    //初始化显示Dialog    protected void onPreExecute() {        if (mShowProgressDialog) {            dialog = new ProgressDialog(mContext);            dialog.setMessage(mContext.getString(R.string.check_new_version));            dialog.show();        }    }    //在后台任务(子线程)中检查服务器的版本信息    @Override    protected String doInBackground(Void... params) {        return getVersionInfo(VERSION_INFO_URL);    }    //后台任务执行完毕后，解除Dialog并且解析return返回的结果    @Override    protected void onPostExecute(String result) {        if (dialog != null && dialog.isShowing()) {            dialog.dismiss();        }        if (!TextUtils.isEmpty(result)) {            parseJson(result);        }    }    /**     * 从服务器取得版本信息     * {       "url":"http://crazyfzw.github.io/demo/auto-update-version/new-version-v2.0.apk",        "versionCode":2,       "updateMessage":"[1]新增视频弹幕功能<br/>[2]优化离线缓存功能<br/>[3]增强了稳定性"       }     * @return     */    public String getVersionInfo(String urlStr){        HttpURLConnection uRLConnection = null;        InputStream is = null;        BufferedReader buffer = null;        String result = null;        try {            URL url = new URL(urlStr);            uRLConnection = (HttpURLConnection) url.openConnection();            uRLConnection.setRequestMethod("GET");            is = uRLConnection.getInputStream();            buffer = new BufferedReader(new InputStreamReader(is));            StringBuilder strBuilder = new StringBuilder();            String line;            while ((line = buffer.readLine()) != null) {                strBuilder.append(line);            }            result = strBuilder.toString();        } catch (Exception e) {            Log.e(TAG, "http post error");        } finally {            if (buffer != null) {                try {                    buffer.close();                } catch (IOException ignored) {                }            }            if (is != null) {                try {                    is.close();                } catch (IOException ignored) {                }            }            if (uRLConnection != null) {                uRLConnection.disconnect();            }        }        return result;    }    /**     *     * @param result     */    private void parseJson(String result) {        try {            JSONObject obj = new JSONObject(result);            String apkUrl = obj.getString("url");                 //APK下载路径            String updateMessage = obj.getString("updateMessage");//版本更新说明            int apkCode = obj.getInt("versionCode");              //新版APK对于的版本号            //取得已经安装在手机的APP的版本号 versionCode            int versionCode = getCurrentVersionCode();            //对比版本号判断是否需要更新            if (apkCode > versionCode) {                    showDialog(updateMessage, apkUrl);            } else if (mShowProgressDialog) {                Toast.makeText(mContext, mContext.getString(R.string.there_no_new_version), Toast.LENGTH_SHORT).show();            }        } catch (JSONException e) {            Log.e(TAG, "parse json error");        }    }    /**     * 取得当前版本号     * @return     */    public int getCurrentVersionCode() {            try {                return mContext.getPackageManager().getPackageInfo(mContext.getPackageName(), 0).versionCode;            } catch (PackageManager.NameNotFoundException ignored) {            }        return 0;    }    /**     * 显示对话框提示用户有新版本，并且让用户选择是否更新版本     * @param content     * @param downloadUrl     */    public void showDialog(String content, final String downloadUrl) {            AlertDialog.Builder builder = new AlertDialog.Builder(mContext);            builder.setTitle(R.string.dialog_choose_update_title);            builder.setMessage(Html.fromHtml(content))                    .setPositiveButton(R.string.dialog_btn_confirm_download, new DialogInterface.OnClickListener() {                        public void onClick(DialogInterface dialog, int id) {                            //下载apk文件                            goToDownloadApk(downloadUrl);                        }                    })                    .setNegativeButton(R.string.dialog_btn_cancel_download, new DialogInterface.OnClickListener() {                        public void onClick(DialogInterface dialog, int id) {                        }                    });            AlertDialog dialog = builder.create();            //点击对话框外面,对话框不消失            dialog.setCanceledOnTouchOutside(false);            dialog.show();    }    /**     * 用intent启用DownloadService服务去下载AKP文件     * @param downloadUrl     */    private void goToDownloadApk(String downloadUrl) {        Intent intent = new Intent(mContext, DownloadApkService.class);        intent.putExtra("apkUrl", downloadUrl);        mContext.startService(intent);    }}

注：其中用到的 StorageUtils.getCacheDirectory(context) 是用于取得应用在手机缓存目录

StorageUtils.java

final class StorageUtils {    private static final String TAG = "StorageUtils";    private static final String EXTERNAL_STORAGE_PERMISSION = "android.permission.WRITE_EXTERNAL_STORAGE";    private StorageUtils() {    }    /**     * Returns application cache directory. Cache directory will be created on SD card     * ("/Android/data/[app_package_name]/cache") if card is mounted and app has appropriate permission. Else -     * Android defines cache directory on device's file system.     */    public static File getCacheDirectory(Context context) {        File appCacheDir = null;        if (MEDIA_MOUNTED.equals(Environment.getExternalStorageState()) && hasExternalStoragePermission(context)) {            appCacheDir = getExternalCacheDir(context);        }        if (appCacheDir == null) {            appCacheDir = context.getCacheDir();        }        if (appCacheDir == null) {            Log.w(TAG, "Can't define system cache directory! The app should be re-installed.");        }        return appCacheDir;    }    private static File getExternalCacheDir(Context context) {        File dataDir = new File(new File(Environment.getExternalStorageDirectory(), "Android"), "data");        File appCacheDir = new File(new File(dataDir, context.getPackageName()), "cache");        if (!appCacheDir.exists()) {            if (!appCacheDir.mkdirs()) {                Log.w(TAG, "Unable to create external cache directory");                return null;            }            try {                new File(appCacheDir, ".nomedia").createNewFile();            } catch (IOException e) {                Log.i(TAG, "Can't create \".nomedia\" file in application external cache directory");            }        }        return appCacheDir;    }    private static boolean hasExternalStoragePermission(Context context) {        int perm = context.checkCallingOrSelfPermission(EXTERNAL_STORAGE_PERMISSION);        return perm == PackageManager.PERMISSION_GRANTED;    }}

3.创建服务(Service)完成apk文件的下载，下载完成后调用系统的安装程序完成安装

DownloadApkService.java

public class DownloadApkService extends IntentService{    private static final int BUFFER_SIZE = 10 * 1024; //缓存大小    private static final String TAG = "DownloadService";    private static final int NOTIFICATION_ID = 0;    private NotificationManager mNotifyManager;    private NotificationCompat.Builder mBuilder;    public DownloadApkService() {        super("DownloadApkService");    }    /**     * 在onHandleIntent中下载apk文件     * @param intent     */    @Override    protected void onHandleIntent(Intent intent) {        //初始化通知，用于显示下载进度        mNotifyManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);        mBuilder = new NotificationCompat.Builder(this);        String appName = getString(getApplicationInfo().labelRes);        int icon = getApplicationInfo().icon;        mBuilder.setContentTitle(appName).setSmallIcon(icon);        String urlStr = intent.getStringExtra("apkUrl"); //从intent中取得apk下载路径        InputStream in = null;        FileOutputStream out = null;        try {            //建立下载连接            URL url = new URL(urlStr);            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();            urlConnection.setRequestMethod("GET");            urlConnection.setDoOutput(false);            urlConnection.setConnectTimeout(10 * 1000);            urlConnection.setReadTimeout(10 * 1000);            urlConnection.setRequestProperty("Connection", "Keep-Alive");            urlConnection.setRequestProperty("Charset", "UTF-8");            urlConnection.setRequestProperty("Accept-Encoding", "gzip, deflate");            urlConnection.connect();            //以文件流读取数据            long bytetotal = urlConnection.getContentLength(); //取得文件长度            long bytesum = 0;            int byteread = 0;            in = urlConnection.getInputStream();            File dir = StorageUtils.getCacheDirectory(this); //取得应用缓存目录            String apkName = urlStr.substring(urlStr.lastIndexOf("/") + 1, urlStr.length());//取得apK文件名            File apkFile = new File(dir, apkName);            out = new FileOutputStream(apkFile);            byte[] buffer = new byte[BUFFER_SIZE];            int limit = 0;            int oldProgress = 0;            while ((byteread = in.read(buffer)) != -1) {                bytesum += byteread;                out.write(buffer, 0, byteread);                int progress = (int) (bytesum * 100L / bytetotal);                // 如果进度与之前进度相等，则不更新，如果更新太频繁，则会造成界面卡顿                if (progress != oldProgress) {                    updateProgress(progress);                }                oldProgress = progress;            }            // 下载完成,调用installAPK开始安装文件            installAPk(apkFile);            Log.d("调试","download apk finish");            mNotifyManager.cancel(NOTIFICATION_ID);        } catch (Exception e) {            Log.e(TAG, "download apk file error");        } finally {            if (out != null) {                try {                    out.close();                } catch (IOException ignored) {                }            }            if (in != null) {                try {                    in.close();                } catch (IOException ignored) {                }            }        }    }    /**     * 实时更新下载进度条显示     * @param progress     */    private void updateProgress(int progress) {        //"正在下载:" + progress + "%"        mBuilder.setContentText(this.getString(R.string.dialog_choose_update_content, progress)).setProgress(100, progress, false);        PendingIntent pendingintent = PendingIntent.getActivity(this, 0, new Intent(), PendingIntent.FLAG_CANCEL_CURRENT);        mBuilder.setContentIntent(pendingintent);        mNotifyManager.notify(NOTIFICATION_ID, mBuilder.build());    }    /**     * 调用系统安装程序安装下载好的apk     * @param apkFile     */    private void installAPk(File apkFile) {        Intent intent = new Intent(Intent.ACTION_VIEW);        //如果没有设置SDCard写权限，或者没有sdcard,apk文件保存在内存中，需要授予权限才能安装        try {            String[] command = {"chmod", "777", apkFile.toString()}; //777代表权限 rwxrwxrwx            ProcessBuilder builder = new ProcessBuilder(command);            builder.start();        } catch (IOException ignored) {        }        intent.setDataAndType(Uri.fromFile(apkFile), "application/vnd.android.package-archive");        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);        startActivity(intent);    }}

4.最后一步，new并execute我们写好的异步任务就行了。

new CheckVersionInfoTask(MainActivity.this, true).execute();

注：记得在AndroidManifest.xml中生明权限及注册Service哦

 <uses-permission android:name="android.permission.INTERNET" />
 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

本案例完整源码：https://github.com/crazyfzw/AppAutoCheckUpdate

用到的相关知识：

异步任务AsysTask的相关用法：郭霖的Android AsyncTask完全解析，带你从源码的角度彻底理解

自动启动线程执行耗时任务并会自动停止的服务 IntentService的用法：Android理解：IntentService

转载请注明出处：http://blog.csdn.net/fzw_faith/article/details/52296037