java pdf转jpg清晰度_java 库 pdfbox 将 pdf 文件转换成高清图片方法

近期需要将 pdf 文件转成高清图片，使用库是 pdfbox、fontbox。可以使用 renderImageWithDPI 方法指定转换的清晰度，当然清晰度越高，转换需要的时间越长，转换出来的图片越大，越清晰。

说明：由于 adobo 软件越来越强大，支持的格式越来越多，这造成了 java 软件有些不能转换。所以对于新的格式可能会有转换问题。

1 引入依赖

org.apache.pdfbox

pdfbox

2.0.16

org.apache.pdfbox

fontbox

2.0.16

2 代码如下

public static voidconvertPdf2Image(String pdfPath, String imageDirPath) {

log.info("start convert pdf file:[{}] to image path:[{}]", pdfPath, imageDirPath);if (!newFile(pdfPath).exists()) {

log.info("pdfFilename:[{}] not exist", pdfPath);return;

}if (!newFile(imageDirPath).exists()) {

log.info("imageDir:[{}] not exist", imageDirPath);return;

}byte[] pdfContent =FileUtil.getFileContentByte(pdfPath);

String filename=FileUtil.getFilename(pdfPath);float dpi = 200;

convertPdf2Image(pdfContent, filename, imageDirPath, dpi);

log.info("convert pdf file:[{}] to image success", filename);

}private static void convertPdf2Image(byte[] pdfContent, String pdfFilename, String imageDirPath, floatdpi) {

log.info("convert pdfFilename:[{}] to imageDir:[{}] with dpi:[{}]", pdfFilename, imageDirPath, dpi);if(ArrayUtils.isEmpty(pdfContent)) {return;

}//为了保证显示清除，至少 90

if (dpi < 90) {

dpi= 90;

}

String baseSir=imageDirPath;if (baseSir.endsWith("/") || baseSir.endsWith("\\")) {

baseSir+= pdfFilename + "_";

}else{

baseSir+= File.separator + pdfFilename + "_";

}

PDDocument document= null;

BufferedOutputStream outputStream= null;try{

document=PDDocument.load(pdfContent);int pageCount =document.getNumberOfPages();

PDFRenderer pdfRenderer= newPDFRenderer(document);

String imgPath;for (int i = 0; i < pageCount; i++) {

imgPath= baseSir + i + ".png";

outputStream= new BufferedOutputStream(newFileOutputStream(imgPath));

BufferedImage image=pdfRenderer.renderImageWithDPI(i, dpi, ImageType.RGB);

ImageIO.write(image,"png", outputStream);

outputStream.close();

log.info("convert to png, total[{}], now[{}], ori:[{}], des[{}]", pageCount, i + 1, pdfFilename, imgPath);

}

}catch(IOException e) {

log.error("convert pdf to image error, pdfFilename:" +pdfFilename, e);

}finally{

IOUtil.closeSilently(outputStream);

IOUtil.closeSilently(document);

}

}//IOUtil.closeSilently 代码

public static voidcloseSilently(Closeable io) {if (io != null) {try{

io.close();

}catch(IOException e) {

e.printStackTrace();

}

}

}

在实际使用中遇到问题

1)ERROR o.a.p.contentstream.PDFStreamEngine 911 - Cannot read JBIG2 image: jbig2-imageio is not installed

2)Cannot read JPEG2000 image: Java Advanced Imaging (JAI) Image I/O Tools are not installed

3) java.lang.IllegalArgumentException: Numbers of source Raster bands and source color space components do not match at java.awt.image.ColorConvertOp.filter

以上两个问题需要使用 JAI 插件和 jbig2 插件支持，通过引入 jai-imageio-core、jai-imageio-jpeg2000、jbig2-imageio

com.twelvemonkeys.imageio

imageio-jpeg

3.4.2

com.github.jai-imageio

jai-imageio-core

1.4.0

com.github.jai-imageio

jai-imageio-jpeg2000

1.3.0

org.apache.pdfbox

jbig2-imageio

3.0.2

参考问题文件

/crazyCodeLove/studentservice/blob/master/sys/src/main/resources/pdffile/000208-p1.pdf

/crazyCodeLove/studentservice/blob/master/sys/src/main/resources/pdffile/001659-p14.pdf

/crazyCodeLove/studentservice/blob/master/sys/src/main/resources/pdffile/main%20doc.pdf

/crazyCodeLove/studentservice/blob/master/sys/src/main/resources/pdffile/573636.pdf

参考文献

/questions/42169154/pdfbox1-8-12-convert-pdf-to-white-page-image

/questions/20424796/pdf-box-generating-blank-images-due-to-jbig2-images-in-it

/qq_15801963/article/details/80746830

/u/2345654/blog/1058192

/questions/18351583/illegalargumentexception-numbers-of-source-raster-bands-and-source-color-space

/questions/10416378/imageio-read-illegal-argument-exception-raster-bands-colour-space-components