com.gccloud.starter.common.utils.excel.WaterMarkSheetWriteHandler Maven / Gradle / Ivy

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package com.gccloud.starter.common.utils.excel;

import com.alibaba.excel.write.handler.SheetWriteHandler;
import com.alibaba.excel.write.metadata.holder.WriteSheetHolder;
import com.alibaba.excel.write.metadata.holder.WriteWorkbookHolder;
import lombok.SneakyThrows;
import lombok.extern.slf4j.Slf4j;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.usermodel.XSSFRelation;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.font.FontRenderContext;
import java.awt.geom.Rectangle2D;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;

/**
 * excel 水印处理
 * 使用案例：EasyExcel.write(filePath, UserExportEntity.class).inMemory(true).registerWriteHandler(new WaterMarkSheetWriteHandler("萌级小菜鸟")).sheet("模板").doWrite(userList);
 *
 * @author liuchengbiao
 * @date 2021/9/26 3:50 下午
 */
@Slf4j
public class WaterMarkSheetWriteHandler implements SheetWriteHandler {
    /**
     * 水印文本
     */
    private String text;

    public WaterMarkSheetWriteHandler(String text) {
        this.text = text;
    }

    public static ByteArrayOutputStream createWaterMark(String content) throws IOException {
        int width = 200;
        int height = 150;
        // 获取bufferedImage对象
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        int fontStyle = Font.BOLD;
        int fontSize = 20;
        // String fontType = "微软雅黑";
        // Font font = new Font(fontType, fontStyle, fontSize);
        Font font = new Font(null, fontStyle, fontSize);
        // 获取Graphics2d对象
        Graphics2D g2d = image.createGraphics();
        image = g2d.getDeviceConfiguration().createCompatibleImage(width, height, Transparency.TRANSLUCENT);
        g2d.dispose();
        g2d = image.createGraphics();
        // 设置字体颜色和透明度，最后一个参数为透明度
        g2d.setColor(new Color(0, 0, 0, 20));
        // 设置字体
        g2d.setStroke(new BasicStroke(1));
        // 设置字体类型  加粗 大小
        g2d.setFont(font);
        // 设置倾斜度
        g2d.rotate(-0.5, (double) image.getWidth() / 2, (double) image.getHeight() / 2);
        FontRenderContext context = g2d.getFontRenderContext();
        Rectangle2D bounds = font.getStringBounds(content, context);
        double x = (width - bounds.getWidth()) / 2;
        double y = (height - bounds.getHeight()) / 2;
        double ascent = -bounds.getY();
        double baseY = y + ascent;
        // 写入水印文字原定高度过小，所以累计写水印，增加高度
        g2d.drawString(content, (int) x, (int) baseY);
        // 设置透明度
        g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER));
        // 释放对象
        g2d.dispose();
        ByteArrayOutputStream os = new ByteArrayOutputStream();
        ImageIO.write(image, "png", os);
        return os;
    }

    public static void putWaterRemarkToExcel(XSSFSheet sheet, byte[] bytes) {
        //add relation from sheet to the picture data
        XSSFWorkbook workbook = sheet.getWorkbook();
        int pictureIdx = workbook.addPicture(bytes, Workbook.PICTURE_TYPE_PNG);
        String rID = sheet.addRelation(null, XSSFRelation.IMAGES, workbook.getAllPictures().get(pictureIdx))
                .getRelationship().getId();
        //set background picture to sheet
        sheet.getCTWorksheet().addNewPicture().setId(rID);
    }

    @Override
    public void beforeSheetCreate(WriteWorkbookHolder writeWorkbookHolder, WriteSheetHolder writeSheetHolder) {
    }

    @SneakyThrows
    @Override
    public void afterSheetCreate(WriteWorkbookHolder writeWorkbookHolder, WriteSheetHolder writeSheetHolder) {
        log.info("设置Excel水印:{}", text);
        log.warn("设置水印比较耗时间，必须采用 inMemory(true) 方式进行，否则会出现类转换失败异常");
        try (ByteArrayOutputStream waterMark = createWaterMark(text)) {
            XSSFSheet sheet = (XSSFSheet) writeSheetHolder.getSheet();
            putWaterRemarkToExcel(sheet, waterMark.toByteArray());
        }
    }
}