Java库将pdf文件转换为高清图像方法

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
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<dependency>
<groupId>org.apache.pdfbox</groupId>
<artifactId>pdfbox</artifactId>
<version>2.0.16</version>
</dependency>
<!–https://mvnrepository.com/artifact/org.apache.pdfbox/fontbox–>
<dependency>
<groupId>org.apache.pdfbox</groupId>
<artifactId>fontbox</artifactId>
<version>2.0.16</version>
</dependency>
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2代码如下
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publicstaticvoidconvertPdf2Image(StringpdfPath,StringimageDirPath){
log.info(“startconvertpdffile:[{}]toimagepath:[{}]”,pdfPath,imageDirPath);
if(!newFile(pdfPath).exists()){
log.info(“pdfFilename:[{}]notexist”,pdfPath);
return;
}
if(!newFile(imageDirPath).exists()){
log.info(“imageDir:[{}]notexist”,imageDirPath);
return;
}
byte[]pdfContent=FileUtil.getFileContentByte(pdfPath);
Stringfilename=FileUtil.getFilename(pdfPath);
floatdpi=200;
convertPdf2Image(pdfContent,filename,imageDirPath,dpi);
log.info(“convertpdffile:[{}]toimagesuccess”,filename);
}
privatestaticvoidconvertPdf2Image(byte[]pdfContent,StringpdfFilename,StringimageDirPath,floatdpi){
log.info(“convertpdfFilename:[{}]toimageDir:[{}]withdpi:[{}]”,pdfFilename,imageDirPath,dpi);
if(ArrayUtils.isEmpty(pdfContent)){
return;
}
//为了保证显示清除，至少90
if(dpi<90){
dpi=90;
}
StringbaseSir=imageDirPath;
if(baseSir.endsWith(“/”)||baseSir.endsWith(“\”)){
baseSir+=pdfFilename+”_”;
}else{
baseSir+=File.separator+pdfFilename+”_”;
}
PDDocumentdocument=null;
BufferedOutputStreamoutputStream=null;
try{
document=PDDocument.load(pdfContent);
intpageCount=document.getNumberOfPages();
PDFRendererpdfRenderer=newPDFRenderer(document);
StringimgPath;
for(inti=0;i<pageCount;i++){
imgPath=baseSir+i+”.png”;
outputStream=newBufferedOutputStream(newFileOutputStream(imgPath));
BufferedImageimage=pdfRenderer.renderImageWithDPI(i,dpi,ImageType.RGB);
ImageIO.write(image,”png”,outputStream);
outputStream.close();
log.info(“converttopng,total[{}],now[{}],ori:[{}],des[{}]”,pageCount,i+1,pdfFilename,imgPath);
}
}catch(IOExceptione){
log.error(“convertpdftoimageerror,pdfFilename:”+pdfFilename,e);
}finally{
IOUtil.closeSilently(outputStream);
IOUtil.closeSilently(document);
}
}
//IOUtil.closeSilently代码
publicstaticvoidcloseSilently(Closeableio){
if(io!=null){
try{
io.close();
}catch(IOExceptione){
e.printStackTrace();
}
}
}
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在实际使用中遇到问题
1）ERRORo.a.p.contentstream.PDFStreamEngine911-CannotreadJBIG2image:jbig2-imageioisnotinstalled
2）CannotreadJPEG2000image:JavaAdvancedImaging(JAI)ImageI/OToolsarenotinstalled
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
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<dependency>
<groupId>com.github.jai-imageio</groupId>
<artifactId>jai-imageio-core</artifactId>
<version>1.4.0</version>
</dependency>
<!–https://mvnrepository.com/artifact/com.github.jai-imageio/jai-imageio-jpeg2000–>
<dependency>
<groupId>com.github.jai-imageio</groupId>
<artifactId>jai-imageio-jpeg2000</artifactId>
<version>1.3.0</version>
</dependency>
<!–https://mvnrepository.com/artifact/org.apache.pdfbox/jbig2-imageio–>
<dependency>
<groupId>org.apache.pdfbox</groupId>
<artifactId>jbig2-imageio</artifactId>
<version>3.0.2</version>
</dependency>