我想使用Android代码创建一个像下载管理器一样的应用程序来从URL下载内容,但我不知道如何开始。
谢谢任何帮助或视频教程。
谢谢任何帮助或视频教程。
/**
* Start Download
*/
public void startDownload() {
DownloadManager mManager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
Request mRqRequest = new Request(
Uri.parse("http://androidtrainningcenter.blogspot.in/2012/11/android-webview-loading-custom-html-and.html"));
mRqRequest.setDescription("This is Test File");
// mRqRequest.setDestinationUri(Uri.parse("give your local path"));
long idDownLoad=mManager.enqueue(mRqRequest);
}
但请确保您的API版本至少为9
这段代码可以从URL下载任何文件,只需替换URL和位置即可。
public class AndroidDownloadFileByProgressBarActivity extends Activity {
// button to show progress dialog
Button btnShowProgress
// Progress Dialog
private ProgressDialog pDialog;
// Progress dialog type (0 - for Horizontal progress bar)
public static final int progress_bar_type = 0;
// File url to download
private static String file_url = " u r l";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// show progress bar button
btnShowProgress = (Button) findViewById(R.id.btnProgressBar);
// Image view to show image after downloading
my_image = (ImageView) findViewById(R.id.my_image);
/**
* Show Progress bar click event
* */
btnShowProgress.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// starting new Async Task
new DownloadFileFromURL().execute(file_url);
}
});
}
@Override
protected Dialog onCreateDialog(int id) {
switch (id) {
case progress_bar_type:
pDialog = new ProgressDialog(this);
pDialog.setMessage("Downloading file. Please wait...");
pDialog.setIndeterminate(false);
pDialog.setMax(100);
pDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
pDialog.setCancelable(true);
pDialog.show();
return pDialog;
default:
return null;
}
}
class DownloadFileFromURL extends AsyncTask<String, String, String> {
/**
* Before starting background thread
* Show Progress Bar Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
showDialog(progress_bar_type);
}
/**
* Downloading file in background thread
* */
@Override
protected String doInBackground(String... f_url) {
int count;
try {
URL url = new URL(f_url[0]);
URLConnection conection = url.openConnection();
conection.connect();
// getting file length
int lenghtOfFile = conection.getContentLength();
// input stream to read file - with 8k buffer
InputStream input = new BufferedInputStream(url.openStream(), 8192);
// Output stream to write file
OutputStream output = new FileOutputStream("/sdcard/downloadedfile.jpg");
byte data[] = new byte[1024];
long total = 0;
while ((count = input.read(data)) != -1) {
total += count;
// publishing the progress....
// After this onProgressUpdate will be called
publishProgress(""+(int)((total*100)/lenghtOfFile));
// writing data to file
output.write(data, 0, count);
}
// flushing output
output.flush();
// closing streams
output.close();
input.close();
} catch (Exception e) {
Log.e("Error: ", e.getMessage());
}
return null;
}
/**
* Updating progress bar
* */
protected void onProgressUpdate(String... progress) {
// setting progress percentage
pDialog.setProgress(Integer.parseInt(progress[0]));
}
/**
* After completing background task
* Dismiss the progress dialog
* **/
@Override
protected void onPostExecute(String file_url) {
// dismiss the dialog after the file was downloaded
dismissDialog(progress_bar_type);
}
}
<!-- Permission: Allow Connect to Internet -->
<uses-permission android:name="android.permission.INTERNET" />
<!-- Permission: Writing to SDCard -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
Main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<!-- Download Button -->
<Button android:id="@+id/btnProgressBar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Download File with Progress Bar"
android:layout_marginTop="50dip"/>
</LinearLayout>
这是用于从URL下载图像的Java代码,您也可以将其与Android应用程序一起使用。
public static void main(String ar[]) throws IOException
{
URL url = new URL("http://zeroturnaround.com/wp-content/uploads/2013/06/no-button-640x480-sky.jpg");
InputStream ios= url.openStream();
OutputStream fou1=new FileOutputStream("/home/delta/Desktop/image.jpg");
byte[] b=new byte[2048];
int length;
while((length=ios.read(b))!=-1)
{
fou1.write(b,0,length);
}
//fio1.close();
fou1.close();
}