将白色背景图片变透明

--非常牛：

package test;


import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.regex.Pattern;

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

public class Picture {

	public static void convert(String path) {
		// TODO Auto-generated constructor stub
		try {
			BufferedImage image = ImageIO.read(new File(path));
			ImageIcon imageIcon = new ImageIcon(image);
			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());
			int alpha = 0;
			for (int j1 = bufferedImage.getMinY(); j1 < bufferedImage
					.getHeight(); j1++) {
				for (int j2 = bufferedImage.getMinX(); j2 < bufferedImage
						.getWidth(); j2++) {
					int rgb = bufferedImage.getRGB(j2, j1);
					if (colorInRange(rgb))
						alpha = 0;
					else
						alpha = 255;
					rgb = (alpha << 24) | (rgb & 0x00ffffff);
					bufferedImage.setRGB(j2, j1, rgb);
				}
			}
			g2D.drawImage(bufferedImage, 0, 0, imageIcon.getImageObserver());
			// 生成图片为PNG
			String outFile = path.substring(0, path.lastIndexOf("."));
			ImageIO.write(bufferedImage, "png", new File(outFile + ".png"));
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public static boolean colorInRange(int color) {
		int red = (color & 0xff0000) >> 16;
		int green = (color & 0x00ff00) >> 8;
		int blue = (color & 0x0000ff);
		if (red >= color_range && green >= color_range && blue >= color_range)
			return true;
		return false;
	}

	public static int color_range = 210;
	public static Pattern pattern = Pattern.compile("[0-9]*");

	public static boolean isNo(String str) {
		return pattern.matcher(str).matches();
	}

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		String path = JOptionPane.showInputDialog(null, "请输入图片目录");
		if (path == null || !new File(path).isDirectory()) {
			JOptionPane.showMessageDialog(null, "输入目录有误！");
			return;
		}
		String color = JOptionPane.showInputDialog(null, "请输入色差范围0~255(建议10~50)");
		if (isNo(color)) {
			color_range = 255 - Integer.parseInt(color);
			File file = new File(path);
			String[] files = file.list();
			for (int i = 0; i < files.length; i++) {
				String ext = files[i].substring(files[i].lastIndexOf(".") + 1);
				if (ext.equals("jpg")) {
					convert(path + "//" + files[i]);
				}
			}
			JOptionPane.showMessageDialog(null, "转换完成！");
		} else {
			JOptionPane.showMessageDialog(null, "输入的数字有误！");
		}
	}

}