Come eseguire il rendering di un file PDF in Android

Android non ha il supporto PDF nelle sue librerie. Esiste un modo per eseguire il rendering dei file PDF nelle applicazioni Android?

Poiché API Livello 21 (Lollipop) Android fornisce una classe PdfRenderer :

// 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();

Per ulteriori informazioni, consultare l' app di esempio .

Per le API meno recenti consiglio la libreria Android PdfViewer , è molto veloce e facile da usare, con licenza Apache License 2.0:

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();

Tratto dal mio blog:

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);
  }
}

Ho adottato un approccio ibrido da alcune delle risposte fornite a questo e ad altri post simili:

Questa soluzione verifica se è installata un'app di lettura PDF e procede come segue: - Se è installato un lettore, scarica il file PDF sul dispositivo e avvia un'app di lettura PDF - Se non è installato alcun lettore, chiedi all'utente se desidera visualizzare il file PDF online tramite Google Drive

NOTA! Questa soluzione utilizza la DownloadManagerclasse Android , introdotta in API9 (Android 2.3 o Gingerbread). Ciò significa che non funziona su Android 2.2 o precedenti.

Ho scritto un post sul blog qui , ma per completezza ho fornito il codice completo di seguito:

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;
    }

}

Scarica qui il codice sorgente ( Visualizza il file PDF all'interno della mia applicazione Android )

Aggiungi questa dipendenza nel tuo Grado: compila 'com.github.barteksc: android-pdf-viewer: 2.0.3'

activity_main.xml

<RelativeLayout android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#ffffff"
    xmlns:android="http://schemas.android.com/apk/res/android" >

    <TextView
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:background="@color/colorPrimaryDark"
        android:text="View PDF"
        android:textColor="#ffffff"
        android:id="@+id/tv_header"
        android:textSize="18dp"
        android:gravity="center"></TextView>

    <com.github.barteksc.pdfviewer.PDFView
        android:id="@+id/pdfView"
        android:layout_below="@+id/tv_header"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>


    </RelativeLayout>

MainActivity.java

import android.app.Activity;
import android.database.Cursor;
import android.net.Uri;
import android.provider.OpenableColumns;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;
import android.widget.RelativeLayout;

import com.github.barteksc.pdfviewer.PDFView;
import com.github.barteksc.pdfviewer.listener.OnLoadCompleteListener;
import com.github.barteksc.pdfviewer.listener.OnPageChangeListener;
import com.github.barteksc.pdfviewer.scroll.DefaultScrollHandle;
import com.shockwave.pdfium.PdfDocument;

import java.util.List;

public class MainActivity extends Activity implements OnPageChangeListener,OnLoadCompleteListener{
    private static final String TAG = MainActivity.class.getSimpleName();
    public static final String SAMPLE_FILE = "android_tutorial.pdf";
    PDFView pdfView;
    Integer pageNumber = 0;
    String pdfFileName;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        pdfView= (PDFView)findViewById(R.id.pdfView);
        displayFromAsset(SAMPLE_FILE);
    }

    private void displayFromAsset(String assetFileName) {
        pdfFileName = assetFileName;

        pdfView.fromAsset(SAMPLE_FILE)
                .defaultPage(pageNumber)
                .enableSwipe(true)

                .swipeHorizontal(false)
                .onPageChange(this)
                .enableAnnotationRendering(true)
                .onLoad(this)
                .scrollHandle(new DefaultScrollHandle(this))
                .load();
    }


    @Override
    public void onPageChanged(int page, int pageCount) {
        pageNumber = page;
        setTitle(String.format("%s %s / %s", pdfFileName, page + 1, pageCount));
    }


    @Override
    public void loadComplete(int nbPages) {
        PdfDocument.Meta meta = pdfView.getDocumentMeta();
        printBookmarksTree(pdfView.getTableOfContents(), "-");

    }

    public void printBookmarksTree(List<PdfDocument.Bookmark> tree, String sep) {
        for (PdfDocument.Bookmark b : tree) {

            Log.e(TAG, String.format("%s %s, p %d", sep, b.getTitle(), b.getPageIdx()));

            if (b.hasChildren()) {
                printBookmarksTree(b.getChildren(), sep + "-");
            }
        }
    }

}

Finalmente sono stato in grado di modificare il codice di butelo per aprire qualsiasi file PDF nel filesystem Android usando pdf.js. Il codice può essere trovato sul mio GitHub

Quello che ho fatto è stato modificato pdffile.jsper leggere l'argomento HTML in filequesto modo:

var url = getURLParameter('file');

function getURLParameter(name) {
return decodeURIComponent((new RegExp('[?|&]' + name + '=' + '([^&;]+?)(&|#|;|$)').exec(location.search)||[,""])[1].replace(/\+/g, '%20'))||null}

Quindi quello che devi fare è semplicemente aggiungere il percorso del file in index.htmlquesto modo:

Uri path = Uri.parse(Environment.getExternalStorageDirectory().toString() + "/data/test.pdf");
webView.loadUrl("file:///android_asset/pdfviewer/index.html?file=" + path);

Aggiorna la pathvariabile in modo che punti a un PDF valido nel filesystem Adroid.

puoi usare un metodo semplice per importazione

implementation 'com.github.barteksc:android-pdf-viewer:2.8.2'

e il codice XML è

<com.github.barteksc.pdfviewer.PDFView
        android:id="@+id/pdfv"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    </com.github.barteksc.pdfviewer.PDFView>

e basta dichiarare e aggiungere un file a una cartella di risorse e assegnare semplicemente il nome

   PDFView  pdfView=findViewById(R.id.pdfv);       
    pdfView.fromAsset("agl.pdf").load();

Per aggiungere un po 'di luce a questo, dovrei andare con la soluzione pdf.js di Mozilla. Ecco il link per un'implementazione già ben scritta di questo: https://bitbucket.org/butelo/pdfviewer/ .

Ecco le modifiche che ho aggiunto nella mia attività Android:

private String getInternalPDFURL(String interalPDFName){
    return "file:///android_asset/pdfviewer/index.html?pdf=" + interalPDFName + ".pdf";
}

Ecco le modifiche che ho apportato pdffile.js:

var url = '../' + getPDFURL();

function getPDFURL(){
    var query = window.location.search.substring(1);
    var vars = query.split("=");
    var pdfPage = vars[1];
    return pdfPage;
}

Ho usato il codice seguente per aprire e stampare il PDF tramite Wi-Fi. Sto inviando tutto il mio codice e spero che sia utile.

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);
        }
    };
}

Non è possibile visualizzare l'anteprima del documento pdf in Android Webview. Se si desidera visualizzare l'anteprima di pdf base64. Richiede una libreria di terze parti.

build.Gradle

compile 'com.github.barteksc:android-pdf-viewer:2.7.0'

dialog_pdf_viewer

<?xml version="1.0" encoding="utf-8"?>

<!--
  ~ Copyright (c) 2017.
  ~ Samet Öztoprak
  ~ All rights reserved.
  -->

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center_horizontal"
    android:orientation="vertical">

    <ImageView
        android:id="@+id/dialog_pdf_viewer_close"
        style="@style/ExitButtonImageViewStyle"
        android:src="@drawable/popup_exit" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:background="@color/white"
        android:orientation="vertical">

        <com.github.barteksc.pdfviewer.PDFView
            android:id="@+id/pdfView"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />

    </LinearLayout>

    <View style="@style/HorizontalLine" />

    <com.pozitron.commons.customviews.ButtonFont
        android:id="@+id/dialog_pdf_viewer_button"
        style="@style/ButtonPrimary2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="15dp"
        android:text="@string/agreed" />

</LinearLayout>

DailogPDFViewer.java

public class DialogPdfViewer extends Dialog {
    PDFView pdfView;
    byte[] decodedString;

    public interface OnDialogPdfViewerListener {
        void onAgreeClick(DialogPdfViewer dialogFullEula);

        void onCloseClick(DialogPdfViewer dialogFullEula);
    }

    public DialogPdfViewer(Context context, String base64, final DialogPdfViewer.OnDialogPdfViewerListener onDialogPdfViewerListener) {
        super(context);

        setContentView(R.layout.dialog_pdf_viewer);
        findViewById(R.id.dialog_pdf_viewer_close).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                onDialogPdfViewerListener.onCloseClick(DialogPdfViewer.this);
            }
        });

        findViewById(R.id.dialog_pdf_viewer_button).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                onDialogPdfViewerListener.onAgreeClick(DialogPdfViewer.this);
            }
        });

        decodedString = Base64.decode(base64.toString(), Base64.DEFAULT);

        pdfView = ((PDFView) findViewById(R.id.pdfView));
        pdfView.fromBytes(decodedString).load();

        setOnKeyListener(new OnKeyListener() {
            @Override
            public boolean onKey(DialogInterface dialog, int keyCode, KeyEvent event) {
                if (keyCode == KeyEvent.KEYCODE_BACK && event.getAction() == KeyEvent.ACTION_DOWN) {
                    onDialogPdfViewerListener.onCloseClick(DialogPdfViewer.this);
                }
                return true;
            }
        });

    }
}