图片加水印，java实现

用java api实现的版本：

import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.RenderingHints;
import java.awt.Transparency;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;

import javax.imageio.ImageIO;
import javax.swing.ImageIcon;

public class ImgMarkUtil {
    /** 
     * 给图片添加水印、可设置水印图片旋转角度 
     * @param iconPath 水印图片路径 
     * @param srcImgPath 源图片路径 
     * @param targerPath 目标图片路径 
     * @param degree 水印图片旋转角度 
     */  
    public static void markImgByIcon(String iconPath, String srcImgPath,  
            String targetPath, Integer degree) {  
        try { 
            Image srcImg = ImageIO.read(new File(srcImgPath));  
  
            BufferedImage buffImg = new BufferedImage(srcImg.getWidth(null),  
                    srcImg.getHeight(null), BufferedImage.TYPE_INT_RGB); 
            Graphics2D g = (Graphics2D)buffImg.getGraphics(); //得到画笔对象  
            
            String srcImgType = srcImgPath.substring(srcImgPath.lastIndexOf(".")+1);
            //如果原图为png或gif格式，设置背景透明
            if("png".equalsIgnoreCase(srcImgType) || "gif".equalsIgnoreCase(srcImgType)) {
                buffImg = g.getDeviceConfiguration().createCompatibleImage(srcImg.getWidth(null),  
                                srcImg.getHeight(null), Transparency.TRANSLUCENT);
                g.dispose();
                g = buffImg.createGraphics();
            }
            
            g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,  
                    RenderingHints.VALUE_INTERPOLATION_BILINEAR);  //设置对线段的锯齿状边缘处理 
            g.drawImage(srcImg, 0, 0, null); //画原图 
            
            if (null != degree) {  
                g.rotate(Math.toRadians(degree), (double) buffImg.getWidth() / 2, 
                                (double) buffImg.getHeight() / 2);  //设置水印旋转  
            }  
  
            //水印图象的路径，水印一般为gif或者png的，这样可设置透明度  
            ImageIcon imgIcon = new ImageIcon(iconPath); 
            Image img = imgIcon.getImage();
  
            float alpha = 0.7f; //透明度  
            g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, alpha)); //设置水印透明度 
            g.drawImage(img, buffImg.getWidth()-img.getWidth(null)-10, 
                            buffImg.getHeight()-img.getHeight(null)-10, null);//画水印
            g.setComposite(AlphaComposite.SrcOver);  //设置回默认值SrcOver
  
            g.dispose();  
  
            ImageIO.write(buffImg, srcImgType, new File(targetPath));// 生成图片 
        } catch (Exception e) {  
            e.printStackTrace();  
        }
        
    }
}

 

除了自己实现，还可以直接用开源的thumbnailator，代码如下：

import java.awt.image.BufferedImage;
import java.io.File;

import javax.imageio.ImageIO;

import net.coobird.thumbnailator.Thumbnails;
import net.coobird.thumbnailator.geometry.Positions;

public class ImgMarkUtil {
    /** 
     * 给图片添加水印、可设置水印图片旋转角度 
     * @param iconPath 水印图片路径 
     * @param srcImgPath 源图片路径 
     * @param targerPath 目标图片路径 
     * @param degree 水印图片旋转角度 
     */  
    public static void markImgByIcon(String iconPath, String srcImgPath,  
            String targetPath, Integer degree) {  
        try {             
            BufferedImage originalImage = ImageIO.read(new File(srcImgPath));
            BufferedImage watermarkImage = ImageIO.read(new File(iconPath));

            BufferedImage thumbnail = Thumbnails.of(originalImage)
                    .size(originalImage.getWidth(), originalImage.getHeight()) 
                    .watermark(Positions.BOTTOM_RIGHT, watermarkImage, 0.7f)
                    .asBufferedImage();
            
            String srcImgType = srcImgPath.substring(srcImgPath.lastIndexOf(".")+1);
            ImageIO.write(thumbnail, srcImgType, new File(targetPath)); 
        } catch (Exception e) {  
            e.printStackTrace();  
        }
        
    }
}