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