IText实现多个pdf转成一个pdf

package com.pdf;

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

import com.lowagie.text.Document;
import com.lowagie.text.DocumentException;
import com.lowagie.text.pdf.PdfCopy;
import com.lowagie.text.pdf.PdfImportedPage;
import com.lowagie.text.pdf.PdfReader;

public class PdfOperate {
public static void main(String[] args) {
String[] files = { "G:/abc/1.pdf", "G:/abc/2.pdf" , "G:/abc/3.pdf", "G:/abc/4.pdf"};
String savepath = "G:/test3.pdf";
morePdfTopdf(files, savepath);
}

public static void morePdfTopdf(String[] files, String savepath) {
Document document = null;
try {
document = new Document(new PdfReader(files[0]).getPageSize(1));
PdfCopy copy = new PdfCopy(document, new FileOutputStream(savepath));
document.open();
for (int i = 0; i < files.length; i++) {
PdfReader reader = new PdfReader(files[i]);
int n = reader.getNumberOfPages();//获得总页码
for (int j = 1; j <= n; j++) {
document.newPage();
PdfImportedPage page = copy.getImportedPage(reader, j);//从当前Pdf,获取第j页
copy.addPage(page);
}
}
} catch (IOException e) {
e.printStackTrace();
} catch (DocumentException e) {
e.printStackTrace();
}finally{
if(document != null){
document.close();
}
}
}
}