Java实现图片加水印且控制位置和透明度.doc

Java实现图片加水印且控制位置和透明度昨天要做一个给图片加水印的功能，不想使用一些插件，就在网上转了一会儿，经过改装成了我需要的功能，代码如下：package org.guhao;import java.awt.AlphaComposite;import java.awt.Graphics2D;import java.awt.Image;import java.awt.image.BufferedImage;import java.io.File;import java.text.SimpleDateFormat;import java.util.Date;import javax.imageio.ImageIO;public class TestWatermark /* 图片水印* param pressimg 水印图片* param targetimg 目标图片* param location 位置：1、左上角，2、右上角，3、左下角，4、右下角，5、正中间* param alpha 透明度*/public static void pressImage(String pressimg, String targetimg, int location, float alpha) try /读取目标图片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);/水印文件Image src_biao = ImageIO.read(new File(pressimg);int width_biao = src_biao.getWidth(null);int height_biao = src_biao.getHeight(null);/如果水印图片高或者宽大于目标图片是做的处理,使其水印宽或高等于目标图片的宽高，并且等比例缩放int new_width_biao = width_biao;int new_height_biao = height_biao;if(width_biao width)new_width_biao = width;new_height_biao = (int) (double)new_width_biao/width_biao*height);if(new_height_biao height)new_height_biao = height;new_width_biao = (int) (double)new_height_biao/height_biao*new_width_biao);/根据位置参数确定坐标位置int x = 0;int y = 0;switch(location)case 1:break;case 2:x = width new_width_biao;break;case 3:y = height new_height_biao;break;case 4:x = width new_width_biao;y = height new_height_biao;break;case 5:x = (width new_width_biao)/2;y = (height new_height_biao)/2;break;default:break;g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, alpha);g.drawImage(src_biao, x, y, new_width_biao, new_height_biao, null);/水印文件结束g.dispose();ImageIO.write( image, “png”, img); catch (Exception e) e.printStackTrace();这个功能我用1000张图片做测试的，平均0.1秒左右操作一张图片，本地测的，如果是服务器的话相信会很快的，但是这个还有一个bug，就是给背 景透明的png图片加水印会使背景变黑，这大概是重新drawImage的时候改变了图片的一些属性，如果那个朋友解决了这个问题记得告诉