Android从URL下载PDF，然后用PDF阅读器打开
我正在尝试编写一个应用程序，从URL下载PDF文件，将其存储在SD上，然后通过Adobe PDF reader或其他应用程序（能够打开PDF）打开 到目前为止，我已经“成功下载并存储在SD卡上”（但每次我试图用PDF阅读器打开PDF时，阅读器都会崩溃并说发生了意外错误），例如 以下是我的下载程序的代码：Android从URL下载PDF，然后用PDF阅读器打开,android,pdf,download,httpurlconnection,fileinputstream,Android,Pdf,Download,Httpurlconnection,Fileinputstream,我正在尝试编写一个应用程序，从URL下载PDF文件，将其存储在SD上，然后通过Adobe PDF reader或其他应用程序（能够打开PDF）打开 到目前为止，我已经“成功下载并存储在SD卡上”（但每次我试图用PDF阅读器打开PDF时，阅读器都会崩溃并说发生了意外错误），例如 以下是我的下载程序的代码： //........code set ui stuff //........code set ui stuff new DownloadFile().execute(fileUrl,
//........code set ui stuff
//........code set ui stuff
new DownloadFile().execute(fileUrl, fileName);
private class DownloadFile extends AsyncTask<String, Void, Void>{
@Override
protected Void doInBackground(String... strings) {
String fileUrl = strings[0]; // -> http://maven.apache.org/maven-1.x/maven.pdf
String fileName = strings[1]; // -> maven.pdf
String extStorageDirectory = Environment.getExternalStorageDirectory().toString();
File folder = new File(extStorageDirectory, "testthreepdf");
folder.mkdir();
File pdfFile = new File(folder, fileName);
try{
pdfFile.createNewFile();
}catch (IOException e){
e.printStackTrace();
}
FileDownloader.downloadFile(fileUrl, pdfFile);
return null;
}
}
public class FileDownloader {
private static final int MEGABYTE = 1024 * 1024;
public static void downloadFile(String fileUrl, File directory){
try {
URL url = new URL(fileUrl);
HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.setDoOutput(true);
urlConnection.connect();
InputStream inputStream = urlConnection.getInputStream();
FileOutputStream fileOutputStream = new FileOutputStream(directory);
int totalSize = urlConnection.getContentLength();
byte[] buffer = new byte[MEGABYTE];
int bufferLength = 0;
while((bufferLength = inputStream.read(buffer))>0 ){
fileOutputStream.write(buffer, 0, bufferLength);
}
fileOutputStream.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
嗨，问题出在FileDownloader类中
urlConnection.setRequestMethod("GET");
urlConnection.setDoOutput(true);
package com.example.downloadread;
import java.io.File;
import java.io.IOException;
import android.app.Activity;
import android.content.ActivityNotFoundException;
import android.content.Intent;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Environment;
import android.view.Menu;
import android.view.View;
import android.widget.Toast;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
public void download(View v)
{
new DownloadFile().execute("http://maven.apache.org/maven-1.x/maven.pdf", "maven.pdf");
}
public void view(View v)
{
File pdfFile = new File(Environment.getExternalStorageDirectory() + "/testthreepdf/" + "maven.pdf"); // -> filename = maven.pdf
Uri path = Uri.fromFile(pdfFile);
Intent pdfIntent = new Intent(Intent.ACTION_VIEW);
pdfIntent.setDataAndType(path, "application/pdf");
pdfIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
try{
startActivity(pdfIntent);
}catch(ActivityNotFoundException e){
Toast.makeText(MainActivity.this, "No Application available to view PDF", Toast.LENGTH_SHORT).show();
}
}
private class DownloadFile extends AsyncTask<String, Void, Void>{
@Override
protected Void doInBackground(String... strings) {
String fileUrl = strings[0]; // -> http://maven.apache.org/maven-1.x/maven.pdf
String fileName = strings[1]; // -> maven.pdf
String extStorageDirectory = Environment.getExternalStorageDirectory().toString();
File folder = new File(extStorageDirectory, "testthreepdf");
folder.mkdir();
File pdfFile = new File(folder, fileName);
try{
pdfFile.createNewFile();
}catch (IOException e){
e.printStackTrace();
}
FileDownloader.downloadFile(fileUrl, pdfFile);
return null;
}
}
}
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.downloadread"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="14"
android:targetSdkVersion="18" />
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"></uses-permission>
<uses-permission android:name="android.permission.READ_PHONE_STATE"></uses-permission>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.downloadread.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<Button
android:id="@+id/button1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginTop="15dp"
android:text="download"
android:onClick="download" />
<Button
android:id="@+id/button2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_below="@+id/button1"
android:layout_marginTop="38dp"
android:text="view"
android:onClick="view" />
</RelativeLayout>
这是下载和查看PDF文件的最佳方法。您可以随时从任何地方调用它
PDFTools.showPDFUrl（上下文，url）
下面是代码。它会很好用的
public class PDFTools {
private static final String TAG = "PDFTools";
private static final String GOOGLE_DRIVE_PDF_READER_PREFIX = "http://drive.google.com/viewer?url=";
private static final String PDF_MIME_TYPE = "application/pdf";
private static final String HTML_MIME_TYPE = "text/html";
public static void showPDFUrl(final Context context, final String pdfUrl ) {
if ( isPDFSupported( context ) ) {
downloadAndOpenPDF(context, pdfUrl);
} else {
askToOpenPDFThroughGoogleDrive( context, pdfUrl );
}
}
@TargetApi(Build.VERSION_CODES.GINGERBREAD)
public static void downloadAndOpenPDF(final Context context, final String pdfUrl) {
// Get filename
//final String filename = pdfUrl.substring( pdfUrl.lastIndexOf( "/" ) + 1 );
String filename = "";
try {
filename = new GetFileInfo().execute(pdfUrl).get();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
// The place where the downloaded PDF file will be put
final File tempFile = new File( context.getExternalFilesDir( Environment.DIRECTORY_DOWNLOADS ), filename );
Log.e(TAG,"File Path:"+tempFile);
if ( tempFile.exists() ) {
// If we have downloaded the file before, just go ahead and show it.
openPDF( context, Uri.fromFile( tempFile ) );
return;
}
// Show progress dialog while downloading
final ProgressDialog progress = ProgressDialog.show( context, context.getString( R.string.pdf_show_local_progress_title ), context.getString( R.string.pdf_show_local_progress_content ), true );
// Create the download request
DownloadManager.Request r = new DownloadManager.Request( Uri.parse( pdfUrl ) );
r.setDestinationInExternalFilesDir( context, Environment.DIRECTORY_DOWNLOADS, filename );
final DownloadManager dm = (DownloadManager) context.getSystemService( Context.DOWNLOAD_SERVICE );
BroadcastReceiver onComplete = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
if ( !progress.isShowing() ) {
return;
}
context.unregisterReceiver( this );
progress.dismiss();
long downloadId = intent.getLongExtra( DownloadManager.EXTRA_DOWNLOAD_ID, -1 );
Cursor c = dm.query( new DownloadManager.Query().setFilterById( downloadId ) );
if ( c.moveToFirst() ) {
int status = c.getInt( c.getColumnIndex( DownloadManager.COLUMN_STATUS ) );
if ( status == DownloadManager.STATUS_SUCCESSFUL ) {
openPDF( context, Uri.fromFile( tempFile ) );
}
}
c.close();
}
};
context.registerReceiver( onComplete, new IntentFilter( DownloadManager.ACTION_DOWNLOAD_COMPLETE ) );
// Enqueue the request
dm.enqueue( r );
}
public static void askToOpenPDFThroughGoogleDrive( final Context context, final String pdfUrl ) {
new AlertDialog.Builder( context )
.setTitle( R.string.pdf_show_online_dialog_title )
.setMessage( R.string.pdf_show_online_dialog_question )
.setNegativeButton( R.string.pdf_show_online_dialog_button_no, null )
.setPositiveButton( R.string.pdf_show_online_dialog_button_yes, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
openPDFThroughGoogleDrive(context, pdfUrl);
}
})
.show();
}
public static void openPDFThroughGoogleDrive(final Context context, final String pdfUrl) {
Intent i = new Intent( Intent.ACTION_VIEW );
i.setDataAndType(Uri.parse(GOOGLE_DRIVE_PDF_READER_PREFIX + pdfUrl ), HTML_MIME_TYPE );
context.startActivity( i );
}
public static final void openPDF(Context context, Uri localUri ) {
Intent i = new Intent( Intent.ACTION_VIEW );
i.setDataAndType( localUri, PDF_MIME_TYPE );
context.startActivity( i );
}
public static boolean isPDFSupported( Context context ) {
Intent i = new Intent( Intent.ACTION_VIEW );
final File tempFile = new File( context.getExternalFilesDir( Environment.DIRECTORY_DOWNLOADS ), "test.pdf" );
i.setDataAndType( Uri.fromFile( tempFile ), PDF_MIME_TYPE );
return context.getPackageManager().queryIntentActivities( i, PackageManager.MATCH_DEFAULT_ONLY ).size() > 0;
}
// get File name from url
static class GetFileInfo extends AsyncTask<String, Integer, String>
{
protected String doInBackground(String... urls)
{
URL url;
String filename = null;
try {
url = new URL(urls[0]);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.connect();
conn.setInstanceFollowRedirects(false);
if(conn.getHeaderField("Content-Disposition")!=null){
String depo = conn.getHeaderField("Content-Disposition");
String depoSplit[] = depo.split("filename=");
filename = depoSplit[1].replace("filename=", "").replace("\"", "").trim();
}else{
filename = "download.pdf";
}
} catch (MalformedURLException e1) {
e1.printStackTrace();
} catch (IOException e) {
}
return filename;
}
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
// use result as file name
}
}
公共类PDFTools{
私有静态最终字符串TAG=“PDFTools”；
私有静态最终字符串GOOGLE\u DRIVE\u PDF\u READER\u PREFIX=”http://drive.google.com/viewer?url=";
私有静态最终字符串PDF\u MIME\u TYPE=“application/PDF”；
私有静态最终字符串HTML\u MIME\u TYPE=“text/HTML”；
公共静态void showPDFUrl（最终上下文，最终字符串pdfUrl）{
如果（isPDFSupported（上下文））{
下载和OpenPDF（上下文，pdfUrl）；
}否则{
askToOpenPDFThroughGoogleDrive（上下文，pdfUrl）；
}
}
@TargetApi（构建版本代码姜饼）
公共静态void downloadOpenPDF（最终上下文，最终字符串pdfUrl）{
//获取文件名
//最终字符串文件名=pdfUrl.substring（pdfUrl.lastIndexOf（“/”）+1）；
字符串filename=“”；
试一试{
filename=new GetFileInfo（）.execute（pdfUrl.get（）；
}捕捉（中断异常e）{
e、 printStackTrace（）；
}捕获（执行例外）{
e、 printStackTrace（）；
}
//下载的PDF文件将放置的位置
final File tempFile=新文件（context.getExternalFilesDir（Environment.DIRECTORY\u下载），文件名）；
Log.e（标记“文件路径：”+tempFile）；
if（tempFile.exists（））{
//如果我们以前下载过该文件，请继续并显示它。
openPDF（context，Uri.fromFile（tempFile））；
返回；
}
//下载时显示进度对话框
final ProgressDialog progress=ProgressDialog.show（上下文，context.getString（R.string.pdf\u show\u local\u progress\u title），context.getString（R.string.pdf\u show\u local\u progress\u content），true）；
//创建下载请求
DownloadManager.Request r=newdownloadmanager.Request（Uri.parse（pdfUrl））；
r、 setDestinationNexternalFilesDir（上下文，Environment.DIRECTORY\u下载，文件名）；
final DownloadManager dm=（DownloadManager）context.getSystemService（context.DOWNLOAD_服务）；
BroadcastReceiver onComplete=新的BroadcastReceiver（）{
@凌驾
公共void onReceive（上下文、意图）{
如果（！progress.isShowing（））{
返回；
}
上下文。未注册接收者（本）；
进步。解散（）；
long downloadId=intent.getLongExtra（DownloadManager.EXTRA\u DOWNLOAD\u ID，-1）；
游标c=dm.query（new DownloadManager.query（）.setFilterById（downloadId））；
if（c.moveToFirst（））{
int status=c.getInt（c.getColumnIndex（DownloadManager.COLUMN_status））；
如果（状态==DownloadManager.status\u成功）{
openPDF（context，Uri.fromFile（tempFile））；
}
}
c、 close（）；
}
};
registerReceiver（onComplete，新的IntentFilter（DownloadManager.ACTION\u DOWNLOAD\u COMPLETE））；
//将请求排队
dm.enqueue（r）；
}
通过GoogleDrive公开静态void asktoopenpdfthr（最终上下文，最终字符串pdfUrl）{
新建AlertDialog.Builder（上下文）
.setTitle（R.string.pdf\u show\u online\u dialog\u title）
.setMessage（R.string.pdf_show_online_dialog_question）
.setNegativeButton（R.string.pdf_show_online_dialog_button_no，null）
.setPositiveButton（R.string.pdf_show_online_dialog_button_yes，new DialogInterface.OnClickListener（）{
@凌驾
public void onClick（DialogInterface dialog，int which）{
openPDFThroughGoogleDrive（上下文，pdfUrl）；
}
})
.show（）；
}
公共静态void openPDFThroughGoogleDrive（最终上下文，最终字符串pdfUrl）{
意向i=新意向（意向.行动\视图）；
i、 setDataAndType（Uri.parse（GOOGLE\u DRIVE\u PDF\u READER\u PREFIX+pdfUrl）、HTML\u MIME\u TYPE）；
背景。起始触觉（i）；
}
公共静态最终void openPDF（上下文上下文，urilocaluri）{
意向i=新意向（意向.行动\视图）；
i、 setDataAndType（localUri、PDF\u MIME\u类型）；
背景。起始触觉（i）；
}
支持公共静态布尔值ISPDFS（上下文）{
意向i=新意向（意向.行动\视图）；
final File tempFile=新文件（context.getExternalFilesDir（Environment.DIRECTORY_下载），“test.pdf”）；
i、 setDataAndType（Uri.fromFile（tempFile），PDF\u MIME\u类型）；
返回context.getPackageManager（）.QueryInputActivities（仅限i，PackageManager.MATCH_DEFAULT_）。size（）>0；
}
//从url获取文件名
静态类GetFileInfo扩展了AsyncTask
{
受保护的字符串doInBackground（字符串…URL）
{
网址；
字符串文件名=null；
试一试{
url=新url（url[0]）；
HttpURLConnection conn=（HttpURLConnect
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<Button
android:id="@+id/button1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginTop="15dp"
android:text="download"
android:onClick="download" />
<Button
android:id="@+id/button2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_below="@+id/button1"
android:layout_marginTop="38dp"
android:text="view"
android:onClick="view" />
</RelativeLayout>
public class PDFTools {
private static final String TAG = "PDFTools";
private static final String GOOGLE_DRIVE_PDF_READER_PREFIX = "http://drive.google.com/viewer?url=";
private static final String PDF_MIME_TYPE = "application/pdf";
private static final String HTML_MIME_TYPE = "text/html";
public static void showPDFUrl(final Context context, final String pdfUrl ) {
if ( isPDFSupported( context ) ) {
downloadAndOpenPDF(context, pdfUrl);
} else {
askToOpenPDFThroughGoogleDrive( context, pdfUrl );
}
}
@TargetApi(Build.VERSION_CODES.GINGERBREAD)
public static void downloadAndOpenPDF(final Context context, final String pdfUrl) {
// Get filename
//final String filename = pdfUrl.substring( pdfUrl.lastIndexOf( "/" ) + 1 );
String filename = "";
try {
filename = new GetFileInfo().execute(pdfUrl).get();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
// The place where the downloaded PDF file will be put
final File tempFile = new File( context.getExternalFilesDir( Environment.DIRECTORY_DOWNLOADS ), filename );
Log.e(TAG,"File Path:"+tempFile);
if ( tempFile.exists() ) {
// If we have downloaded the file before, just go ahead and show it.
openPDF( context, Uri.fromFile( tempFile ) );
return;
}
// Show progress dialog while downloading
final ProgressDialog progress = ProgressDialog.show( context, context.getString( R.string.pdf_show_local_progress_title ), context.getString( R.string.pdf_show_local_progress_content ), true );
// Create the download request
DownloadManager.Request r = new DownloadManager.Request( Uri.parse( pdfUrl ) );
r.setDestinationInExternalFilesDir( context, Environment.DIRECTORY_DOWNLOADS, filename );
final DownloadManager dm = (DownloadManager) context.getSystemService( Context.DOWNLOAD_SERVICE );
BroadcastReceiver onComplete = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
if ( !progress.isShowing() ) {
return;
}
context.unregisterReceiver( this );
progress.dismiss();
long downloadId = intent.getLongExtra( DownloadManager.EXTRA_DOWNLOAD_ID, -1 );
Cursor c = dm.query( new DownloadManager.Query().setFilterById( downloadId ) );
if ( c.moveToFirst() ) {
int status = c.getInt( c.getColumnIndex( DownloadManager.COLUMN_STATUS ) );
if ( status == DownloadManager.STATUS_SUCCESSFUL ) {
openPDF( context, Uri.fromFile( tempFile ) );
}
}
c.close();
}
};
context.registerReceiver( onComplete, new IntentFilter( DownloadManager.ACTION_DOWNLOAD_COMPLETE ) );
// Enqueue the request
dm.enqueue( r );
}
public static void askToOpenPDFThroughGoogleDrive( final Context context, final String pdfUrl ) {
new AlertDialog.Builder( context )
.setTitle( R.string.pdf_show_online_dialog_title )
.setMessage( R.string.pdf_show_online_dialog_question )
.setNegativeButton( R.string.pdf_show_online_dialog_button_no, null )
.setPositiveButton( R.string.pdf_show_online_dialog_button_yes, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
openPDFThroughGoogleDrive(context, pdfUrl);
}
})
.show();
}
public static void openPDFThroughGoogleDrive(final Context context, final String pdfUrl) {
Intent i = new Intent( Intent.ACTION_VIEW );
i.setDataAndType(Uri.parse(GOOGLE_DRIVE_PDF_READER_PREFIX + pdfUrl ), HTML_MIME_TYPE );
context.startActivity( i );
}
public static final void openPDF(Context context, Uri localUri ) {
Intent i = new Intent( Intent.ACTION_VIEW );
i.setDataAndType( localUri, PDF_MIME_TYPE );
context.startActivity( i );
}
public static boolean isPDFSupported( Context context ) {
Intent i = new Intent( Intent.ACTION_VIEW );
final File tempFile = new File( context.getExternalFilesDir( Environment.DIRECTORY_DOWNLOADS ), "test.pdf" );
i.setDataAndType( Uri.fromFile( tempFile ), PDF_MIME_TYPE );
return context.getPackageManager().queryIntentActivities( i, PackageManager.MATCH_DEFAULT_ONLY ).size() > 0;
}
// get File name from url
static class GetFileInfo extends AsyncTask<String, Integer, String>
{
protected String doInBackground(String... urls)
{
URL url;
String filename = null;
try {
url = new URL(urls[0]);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.connect();
conn.setInstanceFollowRedirects(false);
if(conn.getHeaderField("Content-Disposition")!=null){
String depo = conn.getHeaderField("Content-Disposition");
String depoSplit[] = depo.split("filename=");
filename = depoSplit[1].replace("filename=", "").replace("\"", "").trim();
}else{
filename = "download.pdf";
}
} catch (MalformedURLException e1) {
e1.printStackTrace();
} catch (IOException e) {
}
return filename;
}
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
// use result as file name
}
}
package com.deepshikha.openpdf;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.ProgressBar;
public class MainActivity extends AppCompatActivity {
WebView webview;
ProgressBar progressbar;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
webview = (WebView)findViewById(R.id.webview);
progressbar = (ProgressBar) findViewById(R.id.progressbar);
webview.getSettings().setJavaScriptEnabled(true);
String filename ="http://www3.nd.edu/~cpoellab/teaching/cse40816/android_tutorial.pdf";
webview.loadUrl("http://docs.google.com/gview?embedded=true&url=" + filename);
webview.setWebViewClient(new WebViewClient() {
public void onPageFinished(WebView view, String url) {
// do your stuff here
progressbar.setVisibility(View.GONE);
}
});
}
}
String imageurl = response.optString("PdfUrl");
DownloadManager dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
DownloadManager.Request request = new DownloadManager.Request(Uri.parse(imageurl));
request.allowScanningByMediaScanner();
request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED); //Notify client once download is completed!
dm.enqueue(request);