java实现图片加水印

import java.awt.AlphaComposite;    
import java.awt.Color;    
import java.awt.Font;    
import java.awt.Graphics2D;    
import java.awt.Image;    
import java.awt.geom.AffineTransform;    
import java.awt.image.AffineTransformOp;    
import java.awt.image.BufferedImage;    
import java.io.File;    
import java.io.IOException;    
   
import javax.imageio.ImageIO;    
   
/**   
 * @author Eric Xu   
 *   
 */   
public final class ImageUtils {    
    /**   
     * 图片水印   
     * @param pressImg 水印图片   
     * @param targetImg 目标图片   
     * @param x 修正值 默认在中间   
     * @param y 修正值 默认在中间   
     * @param alpha 透明度   
     */   
    public final static void pressImage(String pressImg, String targetImg, int x, int y, float alpha) {    
        try {    
            File img = new File(targetImg);    
            Image src = ImageIO.read(img);    
            int wideth = src.getWidth(null);    
            int height = src.getHeight(null);    
            BufferedImage image = new BufferedImage(wideth, height, BufferedImage.TYPE_INT_RGB);    
            Graphics2D g = image.createGraphics();    
            g.drawImage(src, 0, 0, wideth, height, null);    
            //水印文件    
            Image src_biao = ImageIO.read(new File(pressImg));    
            int wideth_biao = src_biao.getWidth(null);    
            int height_biao = src_biao.getHeight(null);    
            g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, alpha));    
            g.drawImage(src_biao, (wideth - wideth_biao) / 2, (height - height_biao) / 2, wideth_biao, height_biao, null);    
            //水印文件结束    
            g.dispose();    
            ImageIO.write((BufferedImage) image, "jpg", img);    
        } catch (Exception e) {    
            e.printStackTrace();    
        }    
    }    
   
    /**   
     * 文字水印   
     * @param pressText 水印文字   
     * @param targetImg 目标图片   
     * @param fontName 字体名称   
     * @param fontStyle 字体样式   
     * @param color 字体颜色   
     * @param fontSize 字体大小   
     * @param x 修正值   
     * @param y 修正值   
     * @param alpha 透明度   
     */   
    public static void pressText(String pressText, String targetImg, String fontName, int fontStyle, Color color, int fontSize, int x, int y, float alpha) {    
        try {    
            File img = new File(targetImg);    
            Image src = ImageIO.read(img);    
            int width = src.getWidth(null);    
            int height = src.getHeight(null);    
            BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);    
            Graphics2D g = image.createGraphics();    
            g.drawImage(src, 0, 0, width, height, null);    
            g.setColor(color);    
            g.setFont(new Font(fontName, fontStyle, fontSize));    
            g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, alpha));    
            g.drawString(pressText, (width - (getLength(pressText) * fontSize)) / 2 + x, (height - fontSize) / 2 + y);    
            g.dispose();    
            ImageIO.write((BufferedImage) image, "jpg", img);    
        } catch (Exception e) {    
            e.printStackTrace();    
        }    
    }    
   
    /**   
     * 缩放   
     * @param filePath 图片路径   
     * @param height 高度   
     * @param width 宽度   
     * @param bb 比例不对时是否需要补白   
     */   
    public static void resize(String filePath, int height, int width, boolean bb) {    
        try {    
            double ratio = 0.0; //缩放比例     
            File f = new File(filePath);    
            BufferedImage bi = ImageIO.read(f);    
            Image itemp = bi.getScaledInstance(width, height, bi.SCALE_SMOOTH);    
            //计算比例    
            if ((bi.getHeight() > height) || (bi.getWidth() > width)) {    
                if (bi.getHeight() > bi.getWidth()) {    
                    ratio = (new Integer(height)).doubleValue() / bi.getHeight();    
                } else {    
                    ratio = (new Integer(width)).doubleValue() / bi.getWidth();    
                }    
                AffineTransformOp op = new AffineTransformOp(AffineTransform.getScaleInstance(ratio, ratio), null);    
                itemp = op.filter(bi, null);    
            }    
            if (bb) {    
                BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);    
                Graphics2D g = image.createGraphics();    
                g.setColor(Color.white);    
                g.fillRect(0, 0, width, height);    
                if (width == itemp.getWidth(null))    
                    g.drawImage(itemp, 0, (height - itemp.getHeight(null)) / 2, itemp.getWidth(null), itemp.getHeight(null), Color.white, null);    
                else   
                    g.drawImage(itemp, (width - itemp.getWidth(null)) / 2, 0, itemp.getWidth(null), itemp.getHeight(null), Color.white, null);    
                g.dispose();    
                itemp = image;    
            }    
            ImageIO.write((BufferedImage) itemp, "jpg", f);    
        } catch (IOException e) {    
            e.printStackTrace();    
        }    
    }    
   
    public static void main(String[] args) throws IOException {    
        pressImage("f:\\imgtest\\Lyvee_1.jpg", "f:\\imgtest\\Lyvee1_1.jpg", 0, 0, 0.5f);    
        pressText("无条件为你", "i:\\imgtest\\Lyvee1_1.jpg", "黑体", 36, Color.white, 80, 0, 0, 0.3f);    
        resize("f:\\imgtest\\Lyvee1_1.jpg", 500, 500, true);    
    } 
   
    public static int getLength(String text) {    
        int length = 0;    
        for (int i = 0; i < text.length(); i++) {    
            if (new String(text.charAt(i) + "").getBytes().length > 1) {    
                length += 2;    
            } else {    
                length += 1;    
            }    
        }    
        return length / 2;    
    }    
}