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 pdfPdfDocument 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) methodpart1Doc.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) ;}@Overridepublic 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);