java pdf 合并单元格

Java可以使用Apache PDFBox库来实现PDF合并单元格操作。PDFBox是一款开源的Java库，可以用于创建、修改和提取PDF文档。下面介绍如何使用PDFBox来实现PDF合并单元格操作。

1.引入PDFBox库

使用Maven构建工具，添加以下依赖：

<dependency>
<groupId>org.apache.pdfbox</groupId>
<artifactId>pdfbox</artifactId>
<version>2.0.18</version>
</dependency>

2.创建PDF文档

使用PDFBox创建PDF文档，并添加表格和单元格。示例代码如下：

PDDocument document = new PDDocument();
PDPage page = new PDPage();
document.addPage(page);
PDPageContentStream contentStream = new PDPageContentStream(document, page);

//创建表格
float margin = 50;
float tableWidth = page.getMediaBox().getWidth() - (2 * margin);
float yStartNewPage = page.getMediaBox().getHeight() - (2 * margin);
float yStart = yStartNewPage;
float bottomMargin = 70;
List<String[]> rows = new ArrayList<>();
rows.add(new String[] {"Cell 1", "Cell 2", "Cell 3"});
rows.add(new String[] {"Cell 4", "Cell 5", "Cell 6"});
rows.add(new String[] {"Cell 7", "Cell 8", "Cell 9"});
int rowsPerPage = 3;
int start = 0;
boolean drawContent = true;
float footerYPosition = bottomMargin - 15;
BaseTable table = new BaseTable(yStart, yStartNewPage, bottomMargin, tableWidth, margin, document, page, true, drawContent);
Row<PDPage> headerRow = table.createRow(15f);
headerRow.createCell(20, "Header 1");
headerRow.createCell(20, "Header 2");
headerRow.createCell(20, "Header 3");
table.addHeaderRow(headerRow);
while (start < rows.size()) {
Row<PDPage> row = table.createRow(10f);
String[] rowData = rows.get(start++);
row.createCell(20, rowData[0]);
row.createCell(20, rowData[1]);
row.createCell(20, rowData[2]);
table.addRow(row);
if (start % rowsPerPage == 0 || start == rows.size()) {
table.draw();
contentStream.drawLine(margin, footerYPosition, page.getMediaBox().getWidth() - margin, footerYPosition);
writeFooter(contentStream);
if (start != rows.size()) {
contentStream.endText();
contentStream.close();
page = new PDPage();
document.addPage(page);
contentStream = new PDPageContentStream(document, page);
table = new BaseTable(yStartNewPage, yStartNewPage, bottomMargin, tableWidth, margin, document, page, true, drawContent);
table.addHeaderRow(headerRow);
}
}
}
contentStream.close();
document.save("merged_cells.pdf");
document.close();

3.合并单元格

使用PDFBox的PDPageContentStream类可以合并PDF文档中的单元格。示例代码如下：

PDPageContentStream contentStream = new PDPageContentStream(document, page, AppendMode.APPEND, true);
contentStream.beginText();
contentStream.setFont(PDType1Font.HELVETICA, 12);
contentStream.newLineAtOffset(margin + 20, yStartNewPage - 30);
contentStream.showText("Merged cells");
contentStream.endText();
contentStream.moveTextPositionByAmount(0, -60);
PDRectangle rect = table.getCell(0, 0).getRectangle();
float startX = rect.getLowerLeftX();
float startY = rect.getLowerLeftY();
float width = table.getCell(2, 2).getRectangle().getUpperRightX() - startX;
float height = table.getCell(2, 2).getRectangle().getUpperRightY() - startY;
contentStream.addRect(startX, startY, width, height);
contentStream.stroke();
contentStream.close();

以上就是使用Java实现PDF合并单元格的方法。PDFBox库提供了丰富的PDF处理功能，可以自由地创建、修改和提取PDF文档。