Android的库中不支持PDF。有没有办法在Android应用程序中呈现PDF文件?
当前回答
为了给这一点增加一点光明,我将不得不使用Mozilla的pdf.js解决方案。下面是一个已经编写好的实现的链接:https://bitbucket.org/butelo/pdfviewer/。
以下是我在Android Activity中添加的编辑:
private String getInternalPDFURL(String interalPDFName){
return "file:///android_asset/pdfviewer/index.html?pdf=" + interalPDFName + ".pdf";
}
以下是我在pdffile.js中所做的编辑:
var url = '../' + getPDFURL();
function getPDFURL(){
var query = window.location.search.substring(1);
var vars = query.split("=");
var pdfPage = vars[1];
return pdfPage;
}
其他回答
public class MyPdfViewActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
WebView mWebView=new WebView(MyPdfViewActivity.this);
mWebView.getSettings().setJavaScriptEnabled(true);
mWebView.getSettings().setPluginsEnabled(true);
mWebView.loadUrl("https://docs.google.com/gview?embedded=true&url="+LinkTo);
setContentView(mWebView);
}
}
我从这篇文章和其他类似文章的一些答案中得出了一个混合的方法:
此解决方案检查PDF阅读器应用程序是否已安装,并执行以下操作: —如果设备上安装了PDF阅读器,请将PDF文件下载到设备上,并打开PDF阅读器应用 —如果没有安装阅读器,请询问用户是否希望通过谷歌Drive在线查看PDF文件
注意!这个解决方案使用了在API9 (Android 2.3或Gingerbread)中引入的Android DownloadManager类。这意味着它不能在Android 2.2或更早的版本上运行。
我在这里写了一篇关于它的博客文章,但为了完整性,我在下面提供了完整的代码:
public class 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";
/**
* If a PDF reader is installed, download the PDF file and open it in a reader.
* Otherwise ask the user if he/she wants to view it in the Google Drive online PDF reader.<br />
* <br />
* <b>BEWARE:</b> This method
* @param context
* @param pdfUrl
* @return
*/
public static void showPDFUrl( final Context context, final String pdfUrl ) {
if ( isPDFSupported( context ) ) {
downloadAndOpenPDF(context, pdfUrl);
} else {
askToOpenPDFThroughGoogleDrive( context, pdfUrl );
}
}
/**
* Downloads a PDF with the Android DownloadManager and opens it with an installed PDF reader app.
* @param context
* @param 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 );
// The place where the downloaded PDF file will be put
final File tempFile = new File( context.getExternalFilesDir( Environment.DIRECTORY_DOWNLOADS ), filename );
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 );
}
/**
* Show a dialog asking the user if he wants to open the PDF through Google Drive
* @param context
* @param pdfUrl
*/
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 OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
openPDFThroughGoogleDrive(context, pdfUrl);
}
})
.show();
}
/**
* Launches a browser to view the PDF through Google Drive
* @param context
* @param pdfUrl
*/
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 );
}
/**
* Open a local PDF file with an installed reader
* @param context
* @param localUri
*/
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 );
}
/**
* Checks if any apps are installed that supports reading of PDF files.
* @param context
* @return
*/
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;
}
}
因为API Level 21 (Lollipop) Android提供了一个PdfRenderer类:
// create a new renderer
PdfRenderer renderer = new PdfRenderer(getSeekableFileDescriptor());
// let us just render all pages
final int pageCount = renderer.getPageCount();
for (int i = 0; i < pageCount; i++) {
Page page = renderer.openPage(i);
// say we render for showing on the screen
page.render(mBitmap, null, null, Page.RENDER_MODE_FOR_DISPLAY);
// do stuff with the bitmap
// close the page
page.close();
}
// close the renderer
renderer.close();
有关更多信息,请参阅示例应用程序。
对于旧的api,我推荐Android PdfViewer库,它非常快速和容易使用,在Apache许可证2.0下授权:
pdfView.fromAsset(String)
.pages(0, 2, 1, 3, 3, 3) // all pages are displayed by default
.enableSwipe(true)
.swipeHorizontal(false)
.enableDoubletap(true)
.defaultPage(0)
.onDraw(onDrawListener)
.onLoad(onLoadCompleteListener)
.onPageChange(onPageChangeListener)
.onPageScroll(onPageScrollListener)
.onError(onErrorListener)
.enableAnnotationRendering(false)
.password(null)
.scrollHandle(null)
.load();
以下是如何在不使用任何第三方库的情况下从PDF文件中获得位图缩略图的方法。
private fun loadThumbnailFromPdfFile(file:File, thumbnailImageView: ImageView) {
Log.d(TAG, "loadThumbnailFromPdfFile: ")
val mFileDescriptor = ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY)
// This is the PdfRenderer we use to render the PDF.
val mPdfRenderer = PdfRenderer(mFileDescriptor)
//check if pdf have no pages then we can't show pdf thumbnail
if (mPdfRenderer.pageCount <= 0) {
//No pages in pdf, can't show thumbnail
Log.d(TAG, "loadThumbnailFromPdfFile: No pages in pdf")
} else {
//There are page(s) in pdf, can show pdf thumbnail
//Use `openPage` to open a specific page in PDF.
val mCurrentPage = mPdfRenderer.openPage(0)
// Important: the destination bitmap must be ARGB (not RGB).
val bitmap = Bitmap.createBitmap(mCurrentPage.width, mCurrentPage.height, Bitmap.Config.ARGB_8888)
// Here, we render the page onto the Bitmap.
// To render a portion of the page, use the second and third parameter. Pass nulls to get
// the default result.
// Pass either RENDER_MODE_FOR_DISPLAY or RENDER_MODE_FOR_PRINT for the last parameter.
mCurrentPage.render(bitmap, null, null, PdfRenderer.Page.RENDER_MODE_FOR_DISPLAY)
// We are ready to show the Bitmap to user.
thumbnailImageView.setImageBitmap(bitmap)
}
}
我使用下面的代码使用Wi-Fi打开并打印PDF。我正在发送我的整个代码,我希望它是有用的。
public class MainActivity extends Activity {
int Result_code = 1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button mButton = (Button)findViewById(R.id.button1);
mButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
PrintManager printManager = (PrintManager)getSystemService(Context.PRINT_SERVICE);
String jobName = " Document";
printManager.print(jobName, pda, null);
}
});
}
public void openDocument(String name) {
Intent intent = new Intent(android.content.Intent.ACTION_VIEW);
File file = new File(name);
String extension = android.webkit.MimeTypeMap.getFileExtensionFromUrl(Uri.fromFile(file).toString());
String mimetype = android.webkit.MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
if (extension.equalsIgnoreCase("") || mimetype == null) {
// if there is no extension or there is no definite mimetype, still try to open the file
intent.setDataAndType(Uri.fromFile(file), "text/*");
}
else {
intent.setDataAndType(Uri.fromFile(file), mimetype);
}
// custom message for the intent
startActivityForResult((Intent.createChooser(intent, "Choose an Application:")), Result_code);
//startActivityForResult(intent, Result_code);
//Toast.makeText(getApplicationContext(),"There are no email clients installed.", Toast.LENGTH_SHORT).show();
}
@SuppressLint("NewApi")
PrintDocumentAdapter pda = new PrintDocumentAdapter(){
@Override
public void onWrite(PageRange[] pages, ParcelFileDescriptor destination, CancellationSignal cancellationSignal, WriteResultCallback callback){
InputStream input = null;
OutputStream output = null;
try {
String filename = Environment.getExternalStorageDirectory() + "/" + "Holiday.pdf";
File file = new File(filename);
input = new FileInputStream(file);
output = new FileOutputStream(destination.getFileDescriptor());
byte[] buf = new byte[1024];
int bytesRead;
while ((bytesRead = input.read(buf)) > 0) {
output.write(buf, 0, bytesRead);
}
callback.onWriteFinished(new PageRange[]{PageRange.ALL_PAGES});
}
catch (FileNotFoundException ee){
//Catch exception
}
catch (Exception e) {
//Catch exception
}
finally {
try {
input.close();
output.close();
}
catch (IOException e) {
e.printStackTrace();
}
}
}
@Override
public void onLayout(PrintAttributes oldAttributes, PrintAttributes newAttributes, CancellationSignal cancellationSignal, LayoutResultCallback callback, Bundle extras){
if (cancellationSignal.isCanceled()) {
callback.onLayoutCancelled();
return;
}
// int pages = computePageCount(newAttributes);
PrintDocumentInfo pdi = new PrintDocumentInfo.Builder("Name of file").setContentType(PrintDocumentInfo.CONTENT_TYPE_DOCUMENT).build();
callback.onLayoutFinished(pdi, true);
}
};
}
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