通过java压缩带有大图像的pdf

寻找一种压缩PDF格式的图像并输出pdf进行存档的方法。 我无法在创建之前压缩图像，因为它会影响打印质量。

每个pdf的大小约为8MB，其中大部分由2个图像组成。 图像采用png格式，并在生成期间生成pdf（使用第三方生成器）

有没有办法在不使用第三方工具的情况下在java中压缩这些。 我试过pdfbox，itext和第三方exe（neevia），第三方工具是迄今为止给我任何结果的唯一一个（下降到大约半MB）但我不想放弃对exe的控制。 示例代码如下。

import java.io.BufferedReader; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.util.Arrays; import org.apache.pdfbox.exceptions.COSVisitorException; import org.apache.pdfbox.pdmodel.PDDocument; import org.apache.pdfbox.pdmodel.common.PDStream; import com.itextpdf.text.DocumentException; import com.itextpdf.text.pdf.PdfReader; import com.itextpdf.text.pdf.PdfStamper; import com.itextpdf.text.pdf.PdfWriter; public class compressPDF { public static void main (String[] args) throws IOException, DocumentException, COSVisitorException { /* * Using PDF Box */ PDDocument doc; // = new PDDocument(); doc = PDDocument.load("C:/_dev_env_/TEMP/compressPDF/TRPT_135002_1470_20131212_121423.PDF"); PDStream stream= new PDStream(doc); stream.addCompression(); doc.save("C:/_dev_env_/TEMP/compressPDF/compressed_pdfBox.pdf"); doc.close(); /* * Using itext */ PdfReader reader = new PdfReader("C:/_dev_env_/TEMP/compressPDF/TRPT_135002_1470_20131212_121423.PDF"); PdfStamper stamper = new PdfStamper(reader, new FileOutputStream("C:/_dev_env_/TEMP/compressPDF/compressed_Itext.pdf"), PdfWriter.VERSION_1_5); stamper.setFullCompression(); stamper.getWriter().setCompressionLevel(50); int total = reader.getNumberOfPages() + 1; for (int i = 1; i < total; i++) { reader.setPageContent(i, reader.getPageContent(i)); } stamper.close(); reader.close(); /* * Using 3rd party - Neevia */ try { Process process = new ProcessBuilder("C:/Program Files (x86)/neeviaPDF.com/PDFcompress/cmdLine/CLcompr.exe","C:/_dev_env_/TEMP/compressPDF/TRPT_135002_1470_20131212_121423.PDF", "C:/_dev_env_/TEMP/compressPDF/compressed_Neevia.pdf").start(); InputStream is = process.getInputStream(); InputStreamReader isr = new InputStreamReader(is); BufferedReader br = new BufferedReader(isr); String line; System.out.printf("Output of running %s is:", Arrays.toString(args)); while ((line = br.readLine()) != null) { System.out.println(line); } } catch (Exception e) { System.out.println(e); } finally { System.out.println("Created!!"); } } } 

Answer 1

我使用下面的代码进行概念validation…工作一个款待:)感谢Bruno让我走上了正确的道路:)

 package compressPDF; import java.awt.Graphics2D; import java.awt.geom.AffineTransform; import java.awt.image.BufferedImage; import java.io.ByteArrayOutputStream; import java.io.FileOutputStream; import java.io.IOException; import javax.imageio.ImageIO; import com.itextpdf.text.DocumentException; import com.itextpdf.text.pdf.PRStream; import com.itextpdf.text.pdf.PdfName; import com.itextpdf.text.pdf.PdfNumber; import com.itextpdf.text.pdf.PdfObject; import com.itextpdf.text.pdf.PdfReader; import com.itextpdf.text.pdf.PdfStamper; import com.itextpdf.text.pdf.parser.PdfImageObject; public class ResizeImage { /** The resulting PDF file. */ //public static String RESULT = "results/part4/chapter16/resized_image.pdf"; /** The multiplication factor for the image. */ public static float FACTOR = 0.5f; /** * Manipulates a PDF file src with the file dest as result * @param src the original PDF * @param dest the resulting PDF * @throws IOException * @throws DocumentException */ public void manipulatePdf(String src, String dest) throws IOException, DocumentException { PdfName key = new PdfName("ITXT_SpecialId"); PdfName value = new PdfName("123456789"); // Read the file PdfReader reader = new PdfReader(src); int n = reader.getXrefSize(); PdfObject object; PRStream stream; // Look for image and manipulate image stream for (int i = 0; i < n; i++) { object = reader.getPdfObject(i); if (object == null || !object.isStream()) continue; stream = (PRStream)object; // if (value.equals(stream.get(key))) { PdfObject pdfsubtype = stream.get(PdfName.SUBTYPE); System.out.println(stream.type()); if (pdfsubtype != null && pdfsubtype.toString().equals(PdfName.IMAGE.toString())) { PdfImageObject image = new PdfImageObject(stream); BufferedImage bi = image.getBufferedImage(); if (bi == null) continue; int width = (int)(bi.getWidth() * FACTOR); int height = (int)(bi.getHeight() * FACTOR); BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); AffineTransform at = AffineTransform.getScaleInstance(FACTOR, FACTOR); Graphics2D g = img.createGraphics(); g.drawRenderedImage(bi, at); ByteArrayOutputStream imgBytes = new ByteArrayOutputStream(); ImageIO.write(img, "JPG", imgBytes); stream.clear(); stream.setData(imgBytes.toByteArray(), false, PRStream.BEST_COMPRESSION); stream.put(PdfName.TYPE, PdfName.XOBJECT); stream.put(PdfName.SUBTYPE, PdfName.IMAGE); stream.put(key, value); stream.put(PdfName.FILTER, PdfName.DCTDECODE); stream.put(PdfName.WIDTH, new PdfNumber(width)); stream.put(PdfName.HEIGHT, new PdfNumber(height)); stream.put(PdfName.BITSPERCOMPONENT, new PdfNumber(8)); stream.put(PdfName.COLORSPACE, PdfName.DEVICERGB); } } // Save altered PDF PdfStamper stamper = new PdfStamper(reader, new FileOutputStream(dest)); stamper.close(); reader.close(); } /** * Main method. * * @param args no arguments needed * @throws DocumentException * @throws IOException */ public static void main(String[] args) throws IOException, DocumentException { //createPdf(RESULT); new ResizeImage().manipulatePdf("C:/_dev_env_/TEMP/compressPDF/TRPT_135002_1470_20131212_121423.PDF", "C:/_dev_env_/TEMP/compressPDF/compressTest.pdf"); } }