java改变png图片的透明度

java改变png图片的透明度

博客分类：  java

java png 

 package cn;

 import java.awt.Graphics2D;
 import java.awt.image.BufferedImage;
 import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.FileInputStream;

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

 public class ChangeImageAlpha {

 /**
 * 改变png图片的透明度
 * @param srcImageFile 源图像地址
 * @param descImageDir 输出图片的路径和名称
 * @param alpha 输出图片的透明度1-10
 */
 private static void setAlpha(String srcImageFile, String descImageDir,int alpha) {

     try {
     //读取图片
     FileInputStream stream = new FileInputStream(new File(srcImageFile));// 指定要读取的图片

     // 定义一个字节数组输出流，用于转换数组
     ByteArrayOutputStream os = new ByteArrayOutputStream();

     byte[] data =new byte[1024];// 定义一个1K大小的数组
     while (stream.read(data) != -1) {
     os.write(data);
     }

         ImageIcon imageIcon = new ImageIcon(os.toByteArray());
         BufferedImage bufferedImage = new BufferedImage(imageIcon.getIconWidth(), imageIcon.getIconHeight(),
         BufferedImage.TYPE_4BYTE_ABGR);
         Graphics2D g2D = (Graphics2D) bufferedImage.getGraphics();
         g2D.drawImage(imageIcon.getImage(), 0, 0, imageIcon.getImageObserver());

         //判读透明度是否越界
         if (alpha < 0) {
         alpha = 0;
         } else if (alpha > 10) {
         alpha = 10;
         }

         // 循环每一个像素点，改变像素点的Alpha值
         for (int j1 = bufferedImage.getMinY(); j1 < bufferedImage.getHeight(); j1++) {
         for (int j2 = bufferedImage.getMinX(); j2 < bufferedImage.getWidth(); j2++) {
         int rgb = bufferedImage.getRGB(j2, j1);
         rgb = ((alpha * 255 / 10) << 24) | (rgb & 0x00ffffff);
         bufferedImage.setRGB(j2, j1, rgb);
         }
         }
         g2D.drawImage(bufferedImage, 0, 0, imageIcon.getImageObserver());

         // 生成图片为PNG

         ImageIO.write(bufferedImage, "png", new File(descImageDir));

     } catch (Exception e) {
     e.printStackTrace();
     }

 }

 public static void main(String[] args) {
 setAlpha("F:/gfsciy20110326fscjy1999ppp.png","F:/gfsciy20110326fscjy1999ppp-4.png", 4);

 }


 }