java 使用 iText 从 pdf 文件中提取一页
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extracting one page from pdf file using iText
提问by Ahmed
I want to return one page from pdf files from java servlet (to reduce file size download), using itext library. using this code
我想使用 itext 库从 java servlet 的 pdf 文件返回一页（以减少文件大小下载）。使用此代码
try {
PdfReader reader = new PdfReader(input);
Document document = new Document(reader.getPageSizeWithRotation(page_number) );
PdfSmartCopy copy1 = new PdfSmartCopy(document, response.getOutputStream());
copy1.setFullCompression();
document.open();
copy1.addPage(copy1.getImportedPage(reader, page_i) );
copy1.freeReader(reader);
reader.close();
document.close();
} catch (DocumentException e) {
e.printStackTrace();
}
this code returns the page, but the file size is large and some times equals the original file size, even it is just a one page.
此代码返回页面，但文件大小很大，有时甚至等于原始文件大小，即使它只是一页。
回答by Bruno Lowagie
I have downloaded a single file from your repository: Abdomen.pdf
我从您的存储库下载了一个文件：Abdomen.pdf
I have then used the following code to "burst" that PDF:
然后我使用以下代码“爆破”该 PDF：
public static void main(String[] args) throws DocumentException, IOException {
PdfReader reader = new PdfReader("resources/Abdomen.pdf");
int n = reader.getNumberOfPages();
reader.close();
String path;
PdfStamper stamper;
for (int i = 1; i <= n; i++) {
reader = new PdfReader("resources/abdomen.pdf");
reader.selectPages(String.valueOf(i));
path = String.format("results/abdomen/p-%s.pdf", i);
stamper = new PdfStamper(reader,new FileOutputStream(path));
stamper.close();
reader.close();
}
}
To "burst" means to split in separate pages. While the original file Abdomen.pdf is 72,570 KB (about 70.8 MB), the separate pages are much smaller:
“burst”意味着分成不同的页面。虽然原始文件 Abdomen.pdf 为 72,570 KB（约 70.8 MB），但单独的页面要小得多：
I can not reproduce the problem you describe.
我无法重现您描述的问题。
回答by Marc Magon
A bit more updated and a lot cleaner (5.5.6 and up) :
更新了一点，更干净了（5.5.6 及更高版本）：
/**
* 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 {
PdfReader reader = new PdfReader(src);
SmartPdfSplitter splitter = new SmartPdfSplitter(reader);
int part = 1;
while (splitter.hasMorePages()) {
splitter.split(new FileOutputStream("results/merge/part_" + part + ".pdf"), 200000);
part++;
}
reader.close();
}
