在itext7中为跨多页的表格绘制自定义边框

import com.itextpdf.kernel.geom.Rectangle;
import com.itextpdf.kernel.pdf.canvas.PdfCanvas;
import com.itextpdf.layout.element.Table;
import com.itextpdf.layout.renderer.TableRenderer;

public class CustomTableRenderer extends TableRenderer {
    
    public CustomTableRenderer(Table modelElement) {
        super(modelElement);
    }
    
    @Override
    public void draw(DrawContext drawContext) {
        super.draw(drawContext);
        
        // 获取表格的边界框
        Rectangle tableRect = getOccupiedAreaBBox();
        
        // 获取表格的行数和列数
        int numRows = rows.size();
        int numCols = rows.isEmpty() ? 0 : rows.get(0).getCells().size();
        
        // 绘制自定义边框
        PdfCanvas canvas = drawContext.getCanvas();
        canvas.saveState();
        canvas.setLineWidth(2f);
        canvas.setStrokeColor(Color.RED);
        
        for (int row = 0; row < numRows; row++) {
            for (int col = 0; col < numCols; col++) {
                // 获取单元格的边界框
                Rectangle cellRect = rows.get(row).getCells().get(col).getOccupiedAreaBBox();
                
                // 绘制单元格的边框
                canvas.rectangle(cellRect.getLeft(), cellRect.getBottom(), cellRect.getWidth(), cellRect.getHeight());
                canvas.stroke();
            }
        }
        
        canvas.restoreState();
    }
}

import com.itextpdf.kernel.pdf.PdfDocument;
import com.itextpdf.kernel.pdf.PdfWriter;
import com.itextpdf.layout.Document;
import com.itextpdf.layout.element.Cell;
import com.itextpdf.layout.element.Table;

public class CustomTableBorderExample {
    
    public static void main(String[] args) {
        // 创建PDF文档
        PdfDocument pdfDoc = new PdfDocument(new PdfWriter("custom_table_border.pdf"));
        Document doc = new Document(pdfDoc);
        
        // 创建表格
        Table table = new Table(3);
        
        // 设置表格的渲染器为自定义渲染器
        table.setNextRenderer(new CustomTableRenderer(table));
        
        // 添加单元格
        for (int i = 0; i < 10; i++) {
            Cell cell = new Cell().add("Cell " + (i + 1));
            table.addCell(cell);
        }
        
        // 将表格添加到文档中
        doc.add(table);
        
        // 关闭文档
        doc.close();
    }
}