PDF页面的缩略图（Java）

如何使用Java生成PDF文档中页面的缩略图？

Answer 1

我认为http://pdfbox.apache.org/会做你正在寻找的东西，因为你可以从页面创建一个图像，然后缩放图像

从他们的示例代码 –

/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.pdfbox; import java.awt.HeadlessException; import java.awt.Toolkit; import java.awt.image.BufferedImage; import javax.imageio.ImageIO; import java.util.List; import org.apache.pdfbox.exceptions.InvalidPasswordException; import org.apache.pdfbox.pdmodel.PDDocument; import org.apache.pdfbox.pdmodel.PDPage; import org.apache.pdfbox.pdmodel.common.PDRectangle; import org.apache.pdfbox.util.PDFImageWriter; /** * Convert a PDF document to an image. * * @author Ben Litchfield * @version $Revision: 1.6 $ */ public class PDFToImage { private static final String PASSWORD = "-password"; private static final String START_PAGE = "-startPage"; private static final String END_PAGE = "-endPage"; private static final String IMAGE_FORMAT = "-imageType"; private static final String OUTPUT_PREFIX = "-outputPrefix"; private static final String COLOR = "-color"; private static final String RESOLUTION = "-resolution"; private static final String CROPBOX = "-cropbox"; /** * private constructor. */ private PDFToImage() { //static class } /** * Infamous main method. * * @param args Command line arguments, should be one and a reference to a file. * * @throws Exception If there is an error parsing the document. */ public static void main( String[] args ) throws Exception { String password = ""; String pdfFile = null; String outputPrefix = null; String imageFormat = "jpg"; int startPage = 1; int endPage = Integer.MAX_VALUE; String color = "rgb"; int resolution; float cropBoxLowerLeftX = 0; float cropBoxLowerLeftY = 0; float cropBoxUpperRightX = 0; float cropBoxUpperRightY = 0; try { resolution = Toolkit.getDefaultToolkit().getScreenResolution(); } catch( HeadlessException e ) { resolution = 96; } for( int i = 0; i < args.length; i++ ) { if( args[i].equals( PASSWORD ) ) { i++; if( i >= args.length ) { usage(); } password = args[i]; } else if( args[i].equals( START_PAGE ) ) { i++; if( i >= args.length ) { usage(); } startPage = Integer.parseInt( args[i] ); } else if( args[i].equals( END_PAGE ) ) { i++; if( i >= args.length ) { usage(); } endPage = Integer.parseInt( args[i] ); } else if( args[i].equals( IMAGE_FORMAT ) ) { i++; imageFormat = args[i]; } else if( args[i].equals( OUTPUT_PREFIX ) ) { i++; outputPrefix = args[i]; } else if( args[i].equals( COLOR ) ) { i++; color = args[i]; } else if( args[i].equals( RESOLUTION ) ) { i++; resolution = Integer.parseInt(args[i]); } else if( args[i].equals( CROPBOX ) ) { i++; cropBoxLowerLeftX = Float.valueOf(args[i]).floatValue(); i++; cropBoxLowerLeftY = Float.valueOf(args[i]).floatValue(); i++; cropBoxUpperRightX = Float.valueOf(args[i]).floatValue(); i++; cropBoxUpperRightY = Float.valueOf(args[i]).floatValue(); } else { if( pdfFile == null ) { pdfFile = args[i]; } } } if( pdfFile == null ) { usage(); } else { if(outputPrefix == null) { outputPrefix = pdfFile.substring( 0, pdfFile.lastIndexOf( '.' )); } PDDocument document = null; try { document = PDDocument.load( pdfFile ); //document.print(); if( document.isEncrypted() ) { try { document.decrypt( password ); } catch( InvalidPasswordException e ) { if( args.length == 4 )//they supplied the wrong password { System.err.println( "Error: The supplied password is incorrect." ); System.exit( 2 ); } else { //they didn't supply a password and the default of "" was wrong. System.err.println( "Error: The document is encrypted." ); usage(); } } } int imageType = 24; if ("bilevel".equalsIgnoreCase(color)) { imageType = BufferedImage.TYPE_BYTE_BINARY; } else if ("indexed".equalsIgnoreCase(color)) { imageType = BufferedImage.TYPE_BYTE_INDEXED; } else if ("gray".equalsIgnoreCase(color)) { imageType = BufferedImage.TYPE_BYTE_GRAY; } else if ("rgb".equalsIgnoreCase(color)) { imageType = BufferedImage.TYPE_INT_RGB; } else if ("rgba".equalsIgnoreCase(color)) { imageType = BufferedImage.TYPE_INT_ARGB; } else { System.err.println( "Error: the number of bits per pixel must be 1, 8 or 24." ); System.exit( 2 ); } //si une cropBox a ete specifier, appeler la methode de modification de cropbox //changeCropBoxes(PDDocument document,float a, float b, float c,float d) if ( cropBoxLowerLeftX!=0 || cropBoxLowerLeftY!=0 || cropBoxUpperRightX!=0 || cropBoxUpperRightY!=0 ) { changeCropBoxes(document,cropBoxLowerLeftX, cropBoxLowerLeftY, cropBoxUpperRightX, cropBoxUpperRightY); } //Make the call PDFImageWriter imageWriter = new PDFImageWriter(); boolean success = imageWriter.writeImage(document, imageFormat, password, startPage, endPage, outputPrefix, imageType, resolution); if (!success) { System.err.println( "Error: no writer found for image format '" + imageFormat + "'" ); System.exit(1); } } catch (Exception e) { System.err.println(e); } finally { if( document != null ) { document.close(); } } } } /** * This will print the usage requirements and exit. */ private static void usage() { System.err.println( "Usage: java org.apache.pdfbox.PDFToImage [OPTIONS] \n" + " -password  Password to decrypt document\n" + " -imageType  (" + getImageFormats() + ")\n" + " -outputPrefix 
 Filename prefix for image files\n" + " -startPage  The first page to start extraction(1 based)\n" + " -endPage  The last page to extract(inclusive)\n" + " -color  The color depth (valid: bilevel, indexed, gray, rgb, rgba)\n" + " -resolution  The bitmap resolution in dpi\n" + " -cropbox     The page area to export\n" + "  The PDF document to use\n" ); System.exit( 1 ); } private static String getImageFormats() { StringBuffer retval = new StringBuffer(); String[] formats = ImageIO.getReaderFormatNames(); for( int i = 0; i < formats.length; i++ ) { retval.append( formats[i] ); if( i + 1 < formats.length ) { retval.append( "," ); } } return retval.toString(); } private static void changeCropBoxes(PDDocument document,float a, float b, float c,float d) { List pages = document.getDocumentCatalog().getAllPages(); for( int i = 0; i < pages.size(); i++ ) { System.out.println("resizing page"); PDPage page = (PDPage)pages.get( i ); PDRectangle rectangle = new PDRectangle(); rectangle.setLowerLeftX(a); rectangle.setLowerLeftY(b); rectangle.setUpperRightX(c); rectangle.setUpperRightY(d); page.setMediaBox(rectangle); page.setCropBox(rectangle); } } } 

Answer 2

您还可以查看JPedal（详情请访问http://www.jpedal.org/pdf_thumbnail.php ）

Answer 3

IcePdf是我见过的最好的（免费），用于阅读pdf。 JPedal很棒，但不是免费的。

如果您要从普通公众可以发送给您的pdf生成图像，我向您保证（根据经验）您将获得将导致JVM崩溃的pdf。 （即：如果它们是带有所有矢量图形的多层pdf）。 这个pdf是一个会使许多库崩溃的例子（但它是一个完全有效的PDF，没有任何有趣的Javascript等）。

我们已经走上了尝试使用大量库并最终将创建缩略图的工作委托给ImageMagick的路线，ImageMagick是一个高度优化的图像处理C程序。

Answer 4

这篇文章不仅是pdf，还有许多其他文件类型，如办公室，图像，文本….