java后台拼接9宫格头像和添加水印文字，效果：

参考：https://blog.csdn.net/shichen88/article/details/101293541

1、拼接工具类：

package com.bai.blog.utils.files;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.geom.AffineTransform;
import java.awt.geom.RoundRectangle2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

/**
 * 拼接图片 参考：https://blog.csdn.net/shichen88/article/details/101293541
 * FileName: FileSplitUtil
 * Create by: 漠天
 * Date: 2019/12/23
 */
public class FileSplitUtil {

    /**
     * 合成图片
     *
     * @param imagePaths    List<String>
     * @param message       String
     * @param outPutPath    String
     * @throws IOException
     * return String
     */
    public static String overlapImage(List<String> imagePaths, String message, String outPutPath) throws IOException {

        int withAndHeight = 530;//背景图片的宽高

        int dividerWithAndHeight = 20;//divider分割空白宽高

        int sonImageWithAndHeight = 150;//画的子头像图片的宽高

        int sonImageRadius= 30;//画的子头像的圆角

        // 设置背景图片大小，自己添加替换图片逻辑
//        BufferedImage backgroundImage = resizeImage(566, 230, ImageIO.read(new File(backgroundPath)));

        //new一个白色背景板
        BufferedImage backgroundImage = new BufferedImage(withAndHeight,withAndHeight,BufferedImage.TYPE_INT_ARGB);
        backgroundImage.getGraphics().setColor(Color.white);
        backgroundImage.getGraphics().fillRect(0,0,withAndHeight,withAndHeight);
        backgroundImage.getGraphics().dispose();
        backgroundImage = setClip(backgroundImage,30);

        // 初始化有效的图片BufferedImage列表
        List<BufferedImage> bufferedImageList = new ArrayList<>();
        for(String imagePath:imagePaths){
            bufferedImageList.add(setClip(resizeImage(sonImageWithAndHeight, sonImageWithAndHeight, ImageIO.read(new File(imagePath))),sonImageRadius));
        }

        // 获取背景画布
        Graphics2D graphics = backgroundImage.createGraphics();
        // 在背景图片上添加文字
        graphics.setColor(Color.blue);
        graphics.setFont(new Font("宋体", Font.PLAIN, 20));
        graphics.drawString(message, sonImageWithAndHeight/3, sonImageWithAndHeight/3);

        // 画出旋转的文字，在指定位置
        Font font = new Font("宋体", Font.PLAIN, 80);
        AffineTransform affineTransform = new AffineTransform();
        affineTransform.rotate(-Math.toRadians(45), 50, 20);
        Font rotatedFont = font.deriveFont(affineTransform);
        graphics.setFont(rotatedFont);
        graphics.drawString(message, sonImageWithAndHeight, withAndHeight-sonImageWithAndHeight);

        // 在背景图片上添加子图片
        if(bufferedImageList.size()>0){

            if(bufferedImageList.size()<2){

                graphics.drawImage(bufferedImageList.get(0), dividerWithAndHeight, dividerWithAndHeight, withAndHeight-dividerWithAndHeight*2, withAndHeight-dividerWithAndHeight*2, null);

            }else if(bufferedImageList.size()<3){

                int newSonWidth =  withAndHeight/2-dividerWithAndHeight*2;
                int centerPlex =(withAndHeight-newSonWidth)/2;
                graphics.drawImage(bufferedImageList.get(0), dividerWithAndHeight+dividerWithAndHeight/2, centerPlex, newSonWidth, newSonWidth, null);
                graphics.drawImage(bufferedImageList.get(1), newSonWidth+dividerWithAndHeight*2+dividerWithAndHeight/2, centerPlex, newSonWidth, newSonWidth, null);

            }else if(bufferedImageList.size()<10){

                for(int i=0;i<bufferedImageList.size();i++){
                    if(i<3){//012
                        graphics.drawImage(bufferedImageList.get(i), sonImageWithAndHeight*i+dividerWithAndHeight*i+dividerWithAndHeight, dividerWithAndHeight, sonImageWithAndHeight, sonImageWithAndHeight, null);
                    }else if(i<6){//345
                        graphics.drawImage(bufferedImageList.get(i), sonImageWithAndHeight*(i%3)+dividerWithAndHeight*(i%3)+dividerWithAndHeight, sonImageWithAndHeight+dividerWithAndHeight*2, sonImageWithAndHeight, sonImageWithAndHeight, null);
                    }else if(i<9){//678
                        graphics.drawImage(bufferedImageList.get(i), sonImageWithAndHeight*(i%6)+dividerWithAndHeight*(i%6)+dividerWithAndHeight, sonImageWithAndHeight*2+dividerWithAndHeight*3, sonImageWithAndHeight, sonImageWithAndHeight, null);
                    }
                }

            }
        }

        graphics.dispose();

        // 输出新的图片
        ImageIO.write(backgroundImage, "png", new File(outPutPath));
        return outPutPath;
    }

    /**
     * 重新设置图片大小
     *
     * @param width
     * @param height
     * @param bufferedImage
     * @return
     */
    private static BufferedImage resizeImage(int width, int height, BufferedImage bufferedImage) {
        BufferedImage newBufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        newBufferedImage.getGraphics().drawImage(bufferedImage.getScaledInstance(width, height, Image.SCALE_SMOOTH), 0, 0, null);
        return newBufferedImage;
    }


    /**
     * 图片设置圆角 （画白边）
     * @param srcImage  BufferedImage
     * @param radius    Int
     * @param border    Int
     * @param padding   Int
     * @return          BufferedImage
     * @throws IOException
     */
    private static BufferedImage setRadius(BufferedImage srcImage, int radius, int border, int padding) throws IOException{
        int width = srcImage.getWidth();
        int height = srcImage.getHeight();
        int canvasWidth = width + padding * 2;
        int canvasHeight = height + padding * 2;

        BufferedImage image = new BufferedImage(canvasWidth, canvasHeight, BufferedImage.TYPE_INT_ARGB);
        Graphics2D gs = image.createGraphics();
        gs.setComposite(AlphaComposite.Src);
        gs.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        gs.setColor(Color.WHITE);
        gs.fill(new RoundRectangle2D.Float(0, 0, canvasWidth, canvasHeight, radius, radius));
        gs.setComposite(AlphaComposite.SrcAtop);
        gs.drawImage(setClip(srcImage, radius), padding, padding, null);
        if(border !=0){
            gs.setColor(Color.GRAY);
            gs.setStroke(new BasicStroke(border));
            gs.drawRoundRect(padding, padding, canvasWidth - 2 * padding, canvasHeight - 2 * padding, radius, radius);
        }
        gs.dispose();
        return image;
    }

    /**
     * 图片设置圆角
     * @param srcImage  BufferedImage
     * @return          BufferedImage
     * @throws IOException
     */
    private static BufferedImage setRadius(BufferedImage srcImage) throws IOException{
        int radius = (srcImage.getWidth() + srcImage.getHeight()) / 6;
        return setRadius(srcImage, radius, 2, 5);
    }

    /**
     * 图片切圆角
     *  圆角矩形：
     *  RoundRectangle2D rectRound = new RoundRectangle2D.Double(20,30,130,100,18,15);//左上角是(20，30)，宽是130，高是100，圆角的长轴是18，短轴是15。
     *
     * @param srcImage  BufferedImage
     * @param radius    radius
     * @return          BufferedImage
     */
    private static BufferedImage setClip(BufferedImage srcImage, int radius){
        int width = srcImage.getWidth();
        int height = srcImage.getHeight();
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
        Graphics2D gs = image.createGraphics();
        gs.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        gs.setClip(new RoundRectangle2D.Double(0, 0, width, height, radius, radius));
        gs.drawImage(srcImage, 0, 0, null);
        gs.dispose();
        return image;
    }
}

2、调用：

        List<String> formatFilePath = new ArrayList<>();
        formatFilePath.add("D:/JavaLibFiles/Files/1.png");
        formatFilePath.add("D:/JavaLibFiles/Files/2.png");
        formatFilePath.add("D:/JavaLibFiles/Files/3.png");
        formatFilePath.add("D:/JavaLibFiles/Files/4.png");
        formatFilePath.add("D:/JavaLibFiles/Files/5.png");
        formatFilePath.add("D:/JavaLibFiles/Files/6.png");
        formatFilePath.add("D:/JavaLibFiles/Files/7.png");

        String outPutPath = "D:/JavaLibFiles/Files/splitImage.png";

        String message = "测试拼接信息";
        
        String splitResultImagePath = FileSplitUtil.overlapImage(formatFilePath,message,outPutPath);
        // 结果地址：splitResultImagePath