Java用自带的Image IO给图片添加水印

1.  文字水印

import sun.font.FontDesignMetrics;
import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
/**
 * @Author ChengJianSheng
 * @Date 2021/6/10
 */
public class WatermarkUtil
{
    public static void main(String[] args) throws IOException
        {
            addText("F:/1.jpeg", "我的梦想是成为火影");
        }
        /**
         * 加文字水印
         * @param srcPath   原文件路径
         * @param content   文字内容
         * @throws IOException
         */
    public static void addText(String srcPath, String content) throws IOException
    {
        //  读取原图片信息
        BufferedImage srcImage = ImageIO.read(new File(srcPath));
        int width = srcImage.getWidth();
        int height = srcImage.getHeight();
        //  创建画笔，设置绘图区域
        BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        Graphics2D g = bufferedImage.createGraphics();
        g.drawImage(srcImage, 0, 0, width, height, null);
        //        g.drawImage(srcImage.getScaledInstance(width, height, Image.SCALE_SMOOTH), 0, 0, null);
        g.setFont(new Font("宋体", Font.PLAIN, 32));
        g.setColor(Color.RED);
        //  计算文字长度
        int len = g.getFontMetrics(g.getFont()).charsWidth(content.toCharArray(), 0, content.length());
        FontDesignMetrics metrics = FontDesignMetrics.getMetrics(g.getFont());
        int len2 = metrics.stringWidth(content);
        System.out.println(len);
        System.out.println(len2);
        //  计算文字坐标
        int x = width - len - 10;
        int y = height - 20;
        //        int x = width - 2 * len;
        //        int y = height - 1 * len;
        g.drawString(content, x, y);
        g.dispose();
        //  输出文件
        FileOutputStream fos = new FileOutputStream("F:/2.png");
        ImageIO.write(bufferedImage, "png", fos);
        fos.flush();
        fos.close();
    }
}

可以设置文字透明度

g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, 0.8f));

2.  旋转文字

import sun.font.FontDesignMetrics;
import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
/**
 * @Author ChengJianSheng
 * @Date 2021/6/10
 */
public class WatermarkUtil
{
    // 水印透明度
    private static final float alpha = 0.5 f;
    // 水印文字字体
    private static final Font font = new Font("宋体", Font.BOLD, 30);
    // 水印文字颜色
    private static final Color color = Color.RED;
    public static void main(String[] args) throws IOException
        {
            addText("F:/1.jpeg", "图片由木叶村提供，仅供忍者联军使用！");
        }
        /**
         * 加文字水印
         * @param srcPath   原文件路径
         * @param content   文字内容
         * @throws IOException
         */
    public static void addText(String srcPath, String content) throws IOException
    {
        //  读取原图片信息
        BufferedImage srcImage = ImageIO.read(new File(srcPath));
        int width = srcImage.getWidth();
        int height = srcImage.getHeight();
        //  创建画笔，设置绘图区域
        BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        Graphics2D g = bufferedImage.createGraphics();
        g.drawImage(srcImage, 0, 0, width, height, null);
        //        g.drawImage(srcImage.getScaledInstance(width, height, Image.SCALE_SMOOTH), 0, 0, null);
        //  旋转文字
        AffineTransform affineTransform = g.getTransform();
        affineTransform.rotate(Math.toRadians(-30), 0, 0);
        Font rotatedFont = font.deriveFont(affineTransform);
        g.setFont(rotatedFont); // 字体
        g.setColor(color); // 颜色
        g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, alpha)); // 透明度
        //  计算文字长度
        int len = g.getFontMetrics(g.getFont()).charsWidth(content.toCharArray(), 0, content.length());
        FontDesignMetrics metrics = FontDesignMetrics.getMetrics(g.getFont());
        int len2 = metrics.stringWidth(content);
        System.out.println(len);
        System.out.println(len2);
        //  计算水印文字坐标
        int x = width / 5;
        int y = height / 3 * 2;
        g.drawString(content, x, y);
        g.dispose();
        //  输出文件
        FileOutputStream fos = new FileOutputStream("F:/2.png");
        ImageIO.write(bufferedImage, "png", fos);
        fos.flush();
        fos.close();
    }
}

画矩形框

import sun.font.FontDesignMetrics;
import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
/**
 * @Author ChengJianSheng
 * @Date 2021/6/10
 */
public class WatermarkUtil
{
    // 水印透明度
    private static final float alpha = 0.5 f;
    // 水印文字字体
    private static final Font font = new Font("宋体", Font.BOLD, 30);
    // 水印文字颜色
    private static final Color color = Color.RED;
    public static void main(String[] args) throws IOException
        {
            addText("F:/1.jpeg", "图片由木叶村提供，仅供忍者联军使用！");
        }
        /**
         * 加文字水印
         * @param srcPath   原文件路径
         * @param content   文字内容
         * @throws IOException
         */
    public static void addText(String srcPath, String content) throws IOException
    {
        //  读取原图片信息
        BufferedImage srcImage = ImageIO.read(new File(srcPath));
        int width = srcImage.getWidth();
        int height = srcImage.getHeight();
        //  创建画笔，设置绘图区域
        BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        Graphics2D g = bufferedImage.createGraphics();
        g.drawImage(srcImage, 0, 0, width, height, null);
        g.setFont(font); // 字体
        g.setColor(color); // 颜色
        g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, alpha)); // 透明度
        //  计算文字宽高度
        FontDesignMetrics metrics = FontDesignMetrics.getMetrics(font);
        int textWidth = metrics.stringWidth(content); //  文字宽度
        int textHeight = metrics.getHeight(); //  文字高度
        //  计算文字坐标
        int x = (width - textWidth) / 2;
        int y = (height + textHeight) / 2;
        //  写文字
        g.drawString(content, x, y);
        //  画矩形
        int padding = 10; // 内边距
        g.drawRect(x - padding / 2, y - textHeight, textWidth + padding, textHeight + padding);
        g.dispose();
        //  输出文件
        FileOutputStream fos = new FileOutputStream("F:/2.png");
        ImageIO.write(bufferedImage, "png", fos);
        fos.flush();
        fos.close();
    }
}

3.  旋转坐标轴

import sun.font.FontDesignMetrics;
import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
/**
 * @Author ChengJianSheng
 * @Date 2021/6/10
 */
public class WatermarkUtil
{
    // 水印透明度
    private static final float alpha = 0.5 f;
    // 水印文字字体
    private static final Font font = new Font("宋体", Font.BOLD, 30);
    // 水印文字颜色
    private static final Color color = Color.RED;
    public static void main(String[] args) throws IOException
        {
            addText("F:/1.jpeg", "图片由木叶村提供，仅供忍者联军使用！");
        }
        /**
         * 加文字水印
         * @param srcPath   原文件路径
         * @param content   文字内容
         * @throws IOException
         */
    public static void addText(String srcPath, String content) throws IOException
    {
        //  读取原图片信息
        BufferedImage srcImage = ImageIO.read(new File(srcPath));
        int width = srcImage.getWidth();
        int height = srcImage.getHeight();
        //  创建画笔，设置绘图区域
        BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        Graphics2D g = bufferedImage.createGraphics();
        g.drawImage(srcImage, 0, 0, width, height, null);
        g.setFont(font); // 字体
        g.setColor(color); // 颜色
        g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, alpha)); // 透明度
        //  计算文字宽高度
        FontDesignMetrics metrics = FontDesignMetrics.getMetrics(font);
        int textWidth = metrics.stringWidth(content); //  文字宽度
        int textHeight = metrics.getHeight(); //  文字高度
        //  旋转坐标轴
        g.translate(-width / 5, height / 4);
        g.rotate(-30 * Math.PI / 180);
        //  计算文字坐标
        int x = (width - textWidth) / 2;
        int y = (height + textHeight) / 2;
        //  写文字
        g.drawString(content, x, y);
        //  画矩形
        int padding = 10; // 内边距
        g.drawRect(x - padding / 2, y - textHeight, textWidth + padding, textHeight + padding);
        g.dispose();
        //  输出文件
        FileOutputStream fos = new FileOutputStream("F:/2.png");
        ImageIO.write(bufferedImage, "png", fos);
        fos.flush();
        fos.close();
    }
}

结合下载功能，完整的代码如下：

/**
 * 下载
 */
@
GetMapping("/download")
public void download(@RequestParam("mediaId") String mediaId, HttpServletRequest request, HttpServletResponse response) throws IOException
{
    SysFile sysFile = sysFileService.getByMediaId(mediaId);
    if(null == sysFile)
    {
        throw new IllegalArgumentException("文件不存在");
    }
    String mimeType = request.getServletContext().getMimeType(sysFile.getPath());
    System.out.println(mimeType);
    response.setContentType(sysFile.getContentType());
    response.setHeader(HttpHeaders.CONTENT_DISPOSITION, "attachment;filename=" + URLEncoder.encode(sysFile.getOriginalFilename(), "UTF-8"));
    //        FileInputStream fis = new FileInputStream(sysFile.getPath());
    ServletOutputStream sos = response.getOutputStream();
    WatermarkUtil.addText(sysFile.getPath(), "哈哈哈哈", sos);
    //        IOUtils.copy(fis, sos);
    //        IOUtils.closeQuietly(fis);
    IOUtils.closeQuietly(sos);
}

import sun.font.FontDesignMetrics;
import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
/**
 * @Author ChengJianSheng
 * @Date 2021/6/10
 */
public class WatermarkUtil
{
    // 水印透明度
    private static final float alpha = 0.5 f;
    // 水印文字字体
    private static final Font font = new Font("宋体", Font.BOLD, 30);
    // 水印文字颜色
    private static final Color color = Color.RED;
    /**
     * 加文字水印
     * @param srcPath   原文件路径
     * @param content   文字内容
     * @throws IOException
     */
    public static void addText(String srcPath, String content, OutputStream outputStream) throws IOException
    {
        //  读取原图片信息
        BufferedImage srcImage = ImageIO.read(new File(srcPath));
        int width = srcImage.getWidth();
        int height = srcImage.getHeight();
        //  画板
        BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        //  画笔
        Graphics2D g = bufferedImage.createGraphics();
        g.drawImage(srcImage, 0, 0, width, height, null);
        g.setFont(font); // 字体
        g.setColor(color); // 颜色
        g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, alpha)); // 透明度
        //  计算文字宽高度
        FontDesignMetrics metrics = FontDesignMetrics.getMetrics(font);
        int textWidth = metrics.stringWidth(content); //  文字宽度
        int textHeight = metrics.getHeight(); //  文字高度
        //  旋转坐标轴
        g.translate(-width / 5, height / 4);
        g.rotate(-30 * Math.PI / 180);
        //  计算文字坐标
        int x = (width - textWidth) / 2;
        int y = (height + textHeight) / 2;
        //  写文字
        g.drawString(content, x, y);
        //  画矩形
        int padding = 10; // 内边距
        g.drawRect(x - padding / 2, y - textHeight, textWidth + padding, textHeight + padding);
        g.dispose();
        //  输出
        ImageIO.write(bufferedImage, "png", outputStream);
    }
}

另外的写法

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;

/**
 * @ProjectName: test
 * @Package: com.test.utils
 * @ClassName: MyTest
 * @Author: luqiming
 * @Description:
 * @Date: 2020/10/29 11:48
 * @Version: 1.0
 */
public class AddWatermarkUtil {
    public static void waterPress(String srcImgPath, String outImgPath,
                           Color markContentColor, int fontSize, String waterMarkContent) {
        try {
            String[] waterMarkContents = waterMarkContent.split("\\|\\|");
            // 读取原图片信息
            File srcImgFile = new File(srcImgPath);
            Image srcImg = ImageIO.read(srcImgFile);
            int srcImgWidth = srcImg.getWidth(null);
            int srcImgHeight = srcImg.getHeight(null);
            // 加水印
            BufferedImage bufImg = new BufferedImage(srcImgWidth, srcImgHeight, BufferedImage.TYPE_INT_RGB);
            // 得到画笔对象
            Graphics2D g = bufImg.createGraphics();
            // 设置起点
            g.drawImage(srcImg, 0, 0, srcImgWidth, srcImgHeight, null);
            Font font = new Font("宋体", Font.PLAIN, fontSize);
            // 根据图片的背景设置水印颜色
            g.setColor(markContentColor);
            // 设置水印文字字体
            g.setFont(font);
            // 数组长度
            int contentLength = waterMarkContents.length;
            // 获取水印文字中最长的
            int maxLength = 0;
            for (int i = 0; i < contentLength; i++) {
                int fontlen = getWatermarkLength(waterMarkContents[i], g);
                if (maxLength < fontlen) {
                    maxLength = fontlen;
                }
            }

            for (int j = 0; j < contentLength; j++) {
                waterMarkContent = waterMarkContents[j];
                int tempX = 10;
                int tempY = fontSize;
                // 单字符长度
                int tempCharLen = 0;
                // 单行字符总长度临时计算
                int tempLineLen = 0;
                StringBuffer sb = new StringBuffer();
                for (int i = 0; i < waterMarkContent.length(); i++) {
                    char tempChar = waterMarkContent.charAt(i);
                    tempCharLen = getCharLen(tempChar, g);
                    tempLineLen += tempCharLen;
                    if (tempLineLen >= srcImgWidth) {
                        // 长度已经满一行,进行文字叠加
                        g.drawString(sb.toString(), tempX, tempY);
                        // 清空内容,重新追加
                        sb.delete(0, sb.length());
                        tempLineLen = 0;
                    }
                    // 追加字符
                    sb.append(tempChar);
                }
                // 通过设置后两个输入参数给水印定位
                g.drawString(sb.toString(), 20, srcImgHeight - (contentLength - j - 1) * tempY-50);
            }
            g.dispose();

            // 输出图片
            FileOutputStream outImgStream = new FileOutputStream(outImgPath);
            ImageIO.write(bufImg, "jpg", outImgStream);
            outImgStream.flush();
            outImgStream.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static int getCharLen(char c, Graphics2D g) {
        return g.getFontMetrics(g.getFont()).charWidth(c);
    }

    /**
     * 获取水印文字总长度
     *
     * @paramwaterMarkContent水印的文字
     * @paramg
     * @return水印文字总长度
     */
    public static int getWatermarkLength(String waterMarkContent, Graphics2D g) {
        return g.getFontMetrics(g.getFont()).charsWidth(
                waterMarkContent.toCharArray(), 0, waterMarkContent.length());
    }


    public static void main(String[] args) {
        // 原图位置, 输出图片位置, 水印文字颜色, 水印文字
        String font = "张天爱||就很完美||2020-05-27 17:00:00";
        String inputAddress = "F:/UpupooWallpaper/1.jpg";
        String outputAddress = "F:/UpupooWallpaper/1.jpg";
        Color color = Color.GREEN;
        waterPress(inputAddress, outputAddress, color, 50, font);
    }
}

添加效果

关于水印位置，需要修改：

//左下角
 g.drawString(sb.toString(), 0, srcImgHeight - (contentLength - j - 1) * tempY);

//右下角
 g.drawString(sb.toString(), srcImgWidth - maxLength, srcImgHeight - (contentLength - j - 1) * tempY);

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