使用 apache poi api 创建 Word 文档时，如何添加 X of Y 格式的页码？

POI API 中是否指定了任何方法来获取总页数，我可以在文档的页脚中添加页码，但无法添加总页数值。

页数Word取决于很多因素，例如字体大小、段落顶部/底部边距和填充、打印机设置、手动插入的分页符等。所以不能直接存到文件中。它将在运行时计算Word正在渲染其页面。

但是我们可以使用页脚中的字段来计算页码和总页数。

使用最多的示例apache poi 3.14:

import java.io.*;

import org.apache.poi.xwpf.usermodel.*;

import org.apache.poi.xwpf.model.XWPFHeaderFooterPolicy;
//import org.apache.poi.wp.usermodel.HeaderFooterType;

public class CreateWordHeaderFooter {

 public static void main(String[] args) throws Exception {

  XWPFDocument doc= new XWPFDocument();

  // the body content
  XWPFParagraph paragraph = doc.createParagraph();
  XWPFRun run=paragraph.createRun();  
  run.setText("The Body:");

  paragraph = doc.createParagraph();
  run=paragraph.createRun();  
  run.setText("Lorem ipsum.... page 1");

  paragraph = doc.createParagraph();
  run=paragraph.createRun();
  run.addBreak(BreakType.PAGE); 
  run.setText("Lorem ipsum.... page 2");

  paragraph = doc.createParagraph();
  run=paragraph.createRun();
  run.addBreak(BreakType.PAGE); 
  run.setText("Lorem ipsum.... page 3");

  // create header-footer
  XWPFHeaderFooterPolicy headerFooterPolicy = doc.getHeaderFooterPolicy();
  if (headerFooterPolicy == null) headerFooterPolicy = doc.createHeaderFooterPolicy();

  // create header start
  XWPFHeader header = headerFooterPolicy.createHeader(XWPFHeaderFooterPolicy.DEFAULT);
  //XWPFHeader header = doc.createHeader(HeaderFooterType.DEFAULT);

  paragraph = header.getParagraphArray(0);
  if (paragraph == null) paragraph = header.createParagraph();
  paragraph.setAlignment(ParagraphAlignment.LEFT);

  run = paragraph.createRun();  
  run.setText("The Header:");

  // create footer start
  XWPFFooter footer = headerFooterPolicy.createFooter(XWPFHeaderFooterPolicy.DEFAULT);
  //XWPFFooter footer = doc.createFooter(HeaderFooterType.DEFAULT);

  paragraph = footer.getParagraphArray(0);
  if (paragraph == null) paragraph = footer.createParagraph();
  paragraph.setAlignment(ParagraphAlignment.CENTER);

  run = paragraph.createRun();  
  run.setText("Page ");
  paragraph.getCTP().addNewFldSimple().setInstr("PAGE \\* MERGEFORMAT");
  run = paragraph.createRun();  
  run.setText(" of ");
  paragraph.getCTP().addNewFldSimple().setInstr("NUMPAGES \\* MERGEFORMAT");

  FileOutputStream out = new FileOutputStream("CreateWordHeaderFooter.docx");
  doc.write(out);
  out.close();
  doc.close();

 }
}

中的字段Word那么是{PAGE \* MERGEFORMAT} and {NUMPAGES \* MERGEFORMAT}.

对于使用电流apache poi 4.1.2无需XWPFHeaderFooterPolicy using XWPFDocument.createHeader, XWPFDocument.createFooter and HeaderFooterType:

...
//import org.apache.poi.xwpf.model.XWPFHeaderFooterPolicy;
import org.apache.poi.wp.usermodel.HeaderFooterType;
...

  // create header-footer
  //XWPFHeaderFooterPolicy headerFooterPolicy = doc.getHeaderFooterPolicy();
  //if (headerFooterPolicy == null) headerFooterPolicy = doc.createHeaderFooterPolicy();

  // create header start
  //XWPFHeader header = headerFooterPolicy.createHeader(XWPFHeaderFooterPolicy.DEFAULT);
  XWPFHeader header = doc.createHeader(HeaderFooterType.DEFAULT);
...
  // create footer start
  //XWPFFooter footer = headerFooterPolicy.createFooter(XWPFHeaderFooterPolicy.DEFAULT);
  XWPFFooter footer = doc.createFooter(HeaderFooterType.DEFAULT);
...