Question

我想分割PDF文件并添加密码以保护它们。我可以拆分PDF但我无法为每个拆分文件添加密码。从我的代码中我发现错误＆＃34; java.io.IOException：找不到PDF标题签名。＆＃34; 我不知道要解决它们：＆＃39;（

`

public class TestSplitPDF {

private static String USER_PASS = "Hello123";

private static String OWNER_PASS = "12345";


public void createPdf(String filename) throws IOException, DocumentException {

        OutputStream file = new FileOutputStream(new File(filename));
        PdfReader reader = new PdfReader(filename);         
        Document document = new Document();         
        PdfCopy c = new PdfCopy(document,new FileOutputStream(filename));
                    PdfWriter pdfWriter = PdfWriter.getInstance(document, file);
                    pdfWriter.setEncryption(USER_PASS.getBytes(), OWNER_PASS.getBytes(),
                            PdfWriter.AllowPrinting, PdfWriter.STRENGTH128BITS);
                    document = new Document();
                    document.open();
                    int pageSize = reader.getNumberOfPages();
                    System.out.println(filename +" Page : "+pageSize);
                    for (int i=1 ; i<pageSize ; i++) {
                        c.addPage(c.getImportedPage(reader, i));
                    }
                    document.close();
                    file.close();
                    //reader.close();

}

public void SplitPDF () {
      try {
          PdfReader Split_PDF_By_Size = new PdfReader("C:/JavaCode/PDFTest.pdf");          
          Document document=new Document();
          PdfCopy copy=new PdfCopy(document,new FileOutputStream("C:/JavaCode/PDFTest_1.pdf"));
          document.open();          
          int number_of_pages = Split_PDF_By_Size.getNumberOfPages();
          int pagenumber=1; /* To generate file name dynamically */
          int Find_PDF_Size; /* To get PDF size in bytes */
          float combinedsize=0; /* To convert this to Kilobytes and estimate new PDF size */ 
          String FileName = "C:/JavaCode/PDFTest_1.pdf";
          for (int i = 1; i < number_of_pages; i++ ) {
              if (combinedsize==0 && i !=1 ){ /* Generate new file only for second time when first document size
                          exceeds limit and incoming loop counter is not 1 */
                  document = new Document();
                  pagenumber++;
                  FileName="C:/JavaCode/PDFTest_"+ pagenumber+".pdf"; /* Dynamic file name */                    
                  copy = new PdfCopy(document,new FileOutputStream(FileName));
                  document.open();
                  copy.addPage(copy.getImportedPage(Split_PDF_By_Size, i)); /* Import pages from original document */
                  Find_PDF_Size=copy.getCurrentDocumentSize(); /* Estimate PDF size in bytes */           
                  combinedsize=(float)Find_PDF_Size/1024; /* Convert bytes to kilobytes */  
                  }//end if
              else {
                  copy.addPage(copy.getImportedPage(Split_PDF_By_Size, i)); /* Import pages from original document */
                  Find_PDF_Size=copy.getCurrentDocumentSize(); /* Estimate PDF size in bytes */           
                  combinedsize=(float)Find_PDF_Size/1024; /* Convert bytes to kilobytes */  
              }
                  if (combinedsize > 1024 || i==number_of_pages) { /* Close document if the page is the last page or if limit reaches */
                  document.close();
                  combinedsize=0; /* reset variable to generate next file, if required */
                  }//end if
          }//end for
          document.close();
          System.out.println("PDF Split By Size Completed. Number of Documents Created:"+pagenumber);  
          for(int p=1 ; p<pagenumber ; p++) {
         FileName = "C:/JavaCode/PDFTest_"+p+".pdf";
        TestSplitPDF pdf2 = new TestSplitPDF();
        pdf2.createPdf(FileName);
          }//end for     
        }//end try
        catch (Exception i)
        {
            System.out.println(i);
        }//end catch      
}//end splitPDF
public static void main (String args[]) throws IOException, DocumentException {
    TestSplitPDF usePDF = new TestSplitPDF();
    usePDF.SplitPDF();
}



   }

`

感谢您的帮助。

Answer 1

您创建file对象的那一刻，您将销毁您即将阅读的PDF（它变成一个0字节的打开文件）：

OutputStream file = new FileOutputStream(new File(filename));

然后，当您尝试阅读此文件时，您会收到IOException：

PdfReader reader = new PdfReader(filename);

找不到PDF标题签名。这意味着PdfReader在文件开头找不到%PDF-。很明显，为什么会发生这种情况：文件不再是PDF文件，而是一个0字节的文件。

这是你应该如何修复你的方法：

public void createPdf(String src, String dest) throws IOException, DocumentException {
    PdfReader reader = new PdfReader(src);
    PdfStamper stamper = new PdfStamper(reader, new FileOutputStream(dest));
    stamper.setEncryption(USER_PASS.getBytes(), OWNER_PASS.getBytes(),
                        PdfWriter.AllowPrinting, PdfWriter.STRENGTH128BITS);
    stamper.close();
}

您的代码真的难以理解：您正在混合PdfCopy和PdfWriter。请在开始编码之前阅读文档，并且不要使用引用我姓名的iText版本开始编码（我是Lowagie并且你正在使用com.lowagie类）。阅读此页面以获取更多信息：http://itextpdf.com/salesfaq

拆分PDF并在PDF文件中添加密码

1 个答案: