学步园

查了一堆资料，终于从2on1这个例子中有所启示，根据这个改造的方法。

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

import com.lowagie.text.Document;
import com.lowagie.text.DocumentException;
import com.lowagie.text.Rectangle;
import com.lowagie.text.pdf.PdfImportedPage;
import com.lowagie.text.pdf.PdfReader;
import com.lowagie.text.pdf.PdfWriter;

public class PDFUtil {
 public static PdfImportedPage getPage(String file_name,int i){
  
  try {
   File out = new File("2on1.pdf"); // 创建一个输出的临时文件
   FileOutputStream outfile = new FileOutputStream(out);
   PdfReader reader = new PdfReader(file_name);  // 创建reader
   Rectangle psize = reader.getPageSize(1);
   float width = psize.height();
   float height = psize.width();

   // step 1: creation of a document-object
   Document document = new Document(new Rectangle(width, height)); // 创建文件的大小，以前因为没有创建document造成了经常报nullpoint
   PdfWriter writer = PdfWriter.getInstance(document,outfile);
   document.open();
   PdfImportedPage page1 = writer.getImportedPage(reader, i);
   writer.freeReader(reader);
   reader = null;
   writer = null;
   outfile.close();

   return page1;
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (DocumentException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  return null;
 }
}