Android应用自动更新功能实现使用AsyncTask!

转载自http://my.oschina.net/banxi/blog/57988

其实这个自动更新功能大体就是两个三个步骤:

   (1)检查更新

   (2)下载更新

  (3)安装更新  

    检查更新和下载更新其实可以算是一步.因为都比较简单,都是主要是下载.

    1) 当你有新的版本发布时,在一个位置放一个更新的文件.

里面到少放有最新应用的版本号.然后你拿当前应用的版本号和服务器上的版本号对比,就知道要不要下载更新了.

   2 ) 下载这个过程,对于Java来说不是什么难事,因为Java提供了丰富的API.更何况Android内置了HttpClient可用.

   3) 这个,安装过程,其实就是使用一个打开查看此下载文件的 Intent.

  这时需要考虑的是文件下载后放到哪里,安全否.:

 一般就是先检测SD卡.然后选择一个合适的目录.

private void checkUpdate() {

RequestFileInfo requestFileInfo = new RequestFileInfo();
requestFileInfo.fileUrl = "http://www.waitab.com/demo/demo.apk";
String status = Environment.getExternalStorageState();
if (!Environment.MEDIA_MOUNTED.equals(status)) {
ToastUtils.showFailure(getApplicationContext(),
"SDcard cannot use!");
return;
}
requestFileInfo.saveFilePath = Environment
.getExternalStoragePublicDirectory(
Environment.DIRECTORY_DOWNLOADS).getAbsolutePath();
requestFileInfo.saveFileName = "DiTouchClient.apk";
showHorizontalFragmentDialog(R.string.title_wait,
R.string.title_download_update);
new DownlaodUpdateTask().execute(requestFileInfo);

}

上面的进度条显示我已经封装好的了.showHorizontalFragmentDialog()

显然我使用了android-support-v4兼容包来使用Fragment的.

  在进度条中有显示,下载文件大小,已经下载了多少.速度等信息.

   由于涉及到网络操作.所以把这整个逻辑放在AsyncTask中. 

代码如下:

private class DownlaodUpdateTask extends
AsyncTask<RequestFileInfo, ProgressValue, BasicCallResult> {

@Override
protected BasicCallResult doInBackground(RequestFileInfo... params) {
final RequestFileInfo req = params[0];
String apkFileName = "";
try {
URL url = new URL(req.fileUrl); // throw MalformedURLException
HttpURLConnection conn = (HttpURLConnection) url
.openConnection();// throws IOException
Log.i(TAG, "response code:" + conn.getResponseCode());
// 1检查网络连接性
if (HttpURLConnection.HTTP_OK != conn.getResponseCode()) {
return new BasicCallResult(
"Can not connect to the update Server! ", false);
}
i
adff
nt length = conn.getContentLength();
double total = StringUtils.bytes2M(length);
InputStream is = conn.getInputStream();
File path = new File(req.saveFilePath);
if (!path.exists())
path.mkdir();
File apkFile = new File(req.saveFilePath, req.saveFileName);
apkFileName = apkFile.getAbsolutePath();
FileOutputStream fos = new FileOutputStream(apkFile);
ProgressValue progressValue = new ProgressValue(0, " downlaod…");
int count = 0;
long startTime, endTime;
byte buffer[] = new byte[1024];
do {
startTime = System.currentTimeMillis();
int numread = is.read(buffer);
endTime = System.currentTimeMillis();
count += numread;
if (numread <= 0) {
// publish end
break;
}
fos.write(buffer, 0, numread);

double kbPerSecond = Math
.ceil((endTime - startTime) / 1000f);
double current = StringUtils.bytes2M(count);
progressValue.message = String.format(
"%.2f M/%.2f M\t\t%.2fKb/S", total, current,
kbPerSecond);
progressValue.progress = (int) (((float) count / length) * DialogUtil.LONG_PROGRESS_MAX);
publishProgress(progressValue);

} while (true);
fos.flush();
fos.close();

} catch (MalformedURLException e) {
e.printStackTrace();
return new BasicCallResult("Wrong url! ", false);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
return new BasicCallResult("Error: " + e.getLocalizedMessage(),
false);
}
BasicCallResult callResult = new BasicCallResult(
"download finish!", true);
callResult.result = apkFileName;
return callResult;
}

@Override
protected void onPostExecute(BasicCallResult result) {
removeFragmentDialog();
if (result.ok) {
installApk(result.result);
} else {
ToastUtils.showFailure(getApplicationContext(), result.message);
}
}

@Override
protected void onProgressUpdate(ProgressValue... values) {
ProgressValue value = values[0];
updateProgressDialog(value);

}

}

/**
* 安装更新APK.
*
* @param fileUri
*/
private void installApk(String fileUri) {
Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(Uri.parse("file://" + fileUri),
"application/vnd.android.package-archive");
startActivity(intent);
this.finish();

}

PS:Java中传递或者返回多个值,我常用的办法就是将数据封装到一个对象中去.上面用到的一些封装对象如下:

传递多个值用对象是因为AsyncTask设计让你传递一个对象作为传递参数,所以传递对象也需要这样使用.

/**
* 传递给android 设置进度条对象
*
* <a href="http://my.oschina.net/arthor" class="referer" target="_blank">@author</a>  banxi1988
*
*/
public final class ProgressValue {
/**
* 需要设置的进度
*/
public int progress;
/**
* 提示信息
*/
public String message;

public ProgressValue(int progress, String message) {
super();
this.progress = progress;
this.message = message;
}

}

基本的调用返回对象:

public class BasicCallResult {
public String message;
public boolean ok;
public String result;

public BasicCallResult(String message, boolean ok) {
super();
this.message = message;
this.ok = ok;
}

}

传递下载相关信息..

public class RequestFileInfo {
public String fileUrl;
public String saveFilePath;
public String saveFileName;

}