Java生成PDF笔记整理

1. 引入依赖, groupId:com.itextpdf, version:8.0.4, artifactId如下

   kernel,io,layout,forms
   

2. 创建pdf对象

   try(ByteArrayOutputStream outputStream = new ByteArrayOutputStream()){
      PdfWriter writer = new PdfWriter(outputStream, new WriterProperties().setFullCompressionMode(true));
      PdfDocument pdfDoc = new PdfDocument(writer);
      Document document = new Document(pdfDoc, PageSize.LETTER);
      document.setMargins(5, 15, 36, 15);
      // 添加内容 ...
      Table table = .... ; // 创建Table对象
      document.add(table);
      //
      document.close();
      return outputStream.toByteArray() ;
   }
   

3. 在pdf每页顶部固定位置添加页眉

    int numberOfPages = pdfDoc.getNumberOfPages();
    LocalDate now = LocalDate.now();
    String dateContent = "Date : " + now.getYear()+ "/"+ now.getMonthValue() +"/"+ now.getDayOfMonth() ;
    Paragraph dateParagraph = new Paragraph(dateContent)
            .setFontSize(7)
            .setFontColor(ColorConstants.BLACK);
    for (int i = 1; i <= numberOfPages; i++) {
        String pageContent = "Page: "+ i +" of " + numberOfPages ;
        Paragraph pageParagraph = new Paragraph( pageContent)
                .setFontSize(7)
                .setFontColor(ColorConstants.BLACK);
        Rectangle pageSize = pdfDoc.getPage(i).getPageSize();
        float x = pageSize.getWidth() * 0.6f -2;
        float y = pageSize.getTop() - 12;
        doc.showTextAligned(pageParagraph, x, y, i, TextAlignment.LEFT, VerticalAlignment.BOTTOM, 0);
        doc.showTextAligned(dateParagraph, x + 70, y, i, TextAlignment.LEFT, VerticalAlignment.BOTTOM, 0);
    }
   

4. 合并pdf

   // part1Bytes、part2Bytes 为两个pdf文件的字节数组
   try(ByteArrayInputStream part1InputSteam = new ByteArrayInputStream(part1Bytes);
       ByteArrayInputStream part2InputStream = new ByteArrayInputStream(part2Bytes)){
       // Create PdfDocument object of each pdf
       PdfDocument part1Doc = new PdfDocument(new PdfReader(part1InputSteam));
       PdfDocument part2Doc = new PdfDocument(new PdfReader(part2InputStream));
       // 
       merger.merge(part1Doc, 1, part1Doc.getNumberOfPages());
       merger.merge(part2Doc, 1, part2Doc.getNumberOfPages());
       // Source documents can be closed implicitly after merging,
       // by passing true to the setCloseSourceDocuments(boolean) method
       part1Doc.close();
       part2Doc.close();
   }
   

Table 创建及属性配置

1. 创建Table对象

   Cell cell = ... ; 
   // columnWidth 会使得表格的列宽度按照比例分配
   float[] columnWidth = {1, 2, 1};
   Table table = new Table(UnitValue.createPercentArray(columnWidth))
   
   table.addCell(cell);
   

2. 表格填充整个宽度

   table.useAllAvailableWidth();
   // table.setWidth(UnitValue.createPercentValue(100)); // 也可以设置宽度 
   

3. 创建普通文本Cell

   Cell cell = new Cell() ;
   // 填充单元格内容
   Paragraph paragraph = new Paragraph(content).setFontSize(7) ;
   cell.add(paragraph);
   

4. 设置对其方式

     Cell cell = new Cell() ;
    cell.setTextAlignment(TextAlignment.CENTER) ;
    cell.setVerticalAlignment(VerticalAlignment.MIDDLE)
    cell.setHorizontalAlignment(HorizontalAlignment.CENTER) ;
   

5. 创建图片Cell

   ClassPathResource resource = new ClassPathResource("banner.jpg");
   byte[] bannerData = resource.getContentAsByteArray();
   ImageData imageData = ImageDataFactory.create(bannerData);
   Image banner = new Image(imageData);
   // 设置图片宽度
   banner.setWidth(80) ;
   Cell cell = new Cell().add(banner);
   

6. 合并单元格

   table.addCell(new Cell(1, 3).add(new Paragraph("Cell with colspan 3")));
   table.addCell(new Cell(2, 1).add(new Paragraph("Cell with rowspan 2")));
   

7. 去除表格边框

   // 这个设置不生效 table.setBorder(Border.NO_BORDER);
   Cell cell = new Cell() ;
   // ...
   cell.setBorder(Border.NO_BORDER) ;
   

Div 使用

1. 创建Div对象

    Paragraph divHeader = new Paragraph("Hello : 1" )
            .setFontSize(7).setMargins(0,0,0,0).setPaddings(0,0,0,0);
    Paragraph divText = new Paragraph("World : 2")
            .setFontSize(7).setMargins(0,0,0,0).setPaddings(0,0,0,0);
    Div div = new Div().add(divHeader).add(divText)
            .setWidth(160).setPaddings(8, 0, 0, 0)
            .setHorizontalAlignment(HorizontalAlignment.LEFT) ;
   

IEventHandler 使用（符合event事件的时候在pdf中插入内容）

1. 继承IEventHandler 接口, 实现handleEvent 方法

   public abstract class HelloHeaderEventHandler implements IEventHandler {
       private final Document doc;
       private final Table header;
       private final float tableHeight;
   
       protected HelloHeaderEventHandler(Document doc, Table header){
           this.doc = doc ;
           this.header = header ;
           this.tableHeight = this.calTableHeight(header) ;
       }
   
       @Override
       public void handleEvent(Event currentEvent) {
           PdfDocumentEvent docEvent = (PdfDocumentEvent) currentEvent;
           PdfDocument pdfDoc = docEvent.getDocument();
           PdfPage page = docEvent.getPage();
           PdfCanvas canvas = new PdfCanvas(page.newContentStreamBefore(), page.getResources(), pdfDoc);
           PageSize pageSize = pdfDoc.getDefaultPageSize();
           float coordX = pageSize.getX() + doc.getLeftMargin();
           float coordY = pageSize.getTop() - doc.getTopMargin();
           float width = pageSize.getWidth() - doc.getRightMargin() - doc.getLeftMargin();
           float height = getHeaderHeight();
           Rectangle rect = new Rectangle(coordX, coordY, width, height);
           this.doHandleEvent(canvas, rect);
       }
       
       private void doHandleEvent(PdfCanvas canvas, Rectangle rect) {
           new Canvas(canvas, rect)
                   .add(header)
                   .close();
       }
       
       private float getHeaderHeight() {
           return tableHeight;
       }
   
       private float calTableHeight(Table table){
           TableRenderer renderer = (TableRenderer) table.createRendererSubTree();
           renderer.setParent(new DocumentRenderer(doc));
           // Simulate the positioning of the renderer to find out how much space the header table will occupy.
           LayoutResult result = renderer.layout(new LayoutContext(new LayoutArea(0, PageSize.A4)));
           return result.getOccupiedArea().getBBox().getHeight();
       }
   }
   

2. PdfDocument 对象添加事件

   PdfWriter writer = new PdfWriter(outputStream, new WriterProperties().setFullCompressionMode(true));
   PdfDocument pdfDoc = new PdfDocument(writer);
   Document document = new Document(pdfDoc, PageSize.LETTER);
   // 
   Table header = ...; // 创建Table对象
   IEventHandler eventHandler = new HelloHeaderEventHandler(document, header)
   pdfDoc.addEventHandler(PdfDocumentEvent.END_PAGE, eventHandler);
   // 设置页面边距
   float topMargin = 3 + eventHandler.getHeaderHeight();
   document.setMargins(topMargin, 15, 36, 15);