缩小图片工具类

package com.juqi.group.common.util;

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

import javax.imageio.ImageIO;


public class ImageUtil {

	/**
	 * 缩小图片
	 * 
	 * @param srcFile
	 *            原图片
	 * @param destFile
	 *            目标图片
	 * @param multiple
	 *            缩略倍数       
	 * @throws IOException
	 */
	public static void resizeFix(File srcFile, File destFile,float multiple) throws IOException {
		BufferedImage srcImgBuff = ImageIO.read(srcFile);
		int width = srcImgBuff.getWidth();
		int height = srcImgBuff.getHeight();
		int zoomWidth = (int)(width *multiple);
		int zoomHeight = (int)(height *multiple);
		BufferedImage imgBuff = scaleImage(srcImgBuff, width, height,
				zoomWidth, zoomHeight);
		writeFile(imgBuff, destFile);
	}
	

	public static void writeFile(BufferedImage imgBuf, File destFile)
			throws IOException {
		File parent = destFile.getParentFile();
		if (!parent.exists()) {
			parent.mkdirs();
		}
		ImageIO.write(imgBuf, "jpeg", destFile);
	}

	private static BufferedImage scaleImage(BufferedImage srcImgBuff,
			int width, int height, int zoomWidth, int zoomHeight) {
		int[] colorArray = srcImgBuff.getRGB(0, 0, width, height, null, 0,
				width);
		BufferedImage outBuff = new BufferedImage(zoomWidth, zoomHeight,
				BufferedImage.TYPE_INT_RGB);
		// 宽缩小的倍数
		float wScale = (float) width / zoomWidth;
		int wScaleInt = (int) (wScale + 0.5);
		// 高缩小的倍数
		float hScale = (float) height / zoomHeight;
		int hScaleInt = (int) (hScale + 0.5);
		int area = wScaleInt * hScaleInt;
		int x0, x1, y0, y1;
		int color;
		long red, green, blue;
		int x, y, i, j;
		for (y = 0; y < zoomHeight; y++) {
			// 得到原图高的Y坐标
			y0 = (int) (y * hScale);
			y1 = y0 + hScaleInt;
			for (x = 0; x < zoomWidth; x++) {
				x0 = (int) (x * wScale);
				x1 = x0 + wScaleInt;
				red = green = blue = 0;
				for (i = x0; i < x1; i++) {
					for (j = y0; j < y1; j++) {
						color = colorArray[width * j + i];
						red += getRedValue(color);
						green += getGreenValue(color);
						blue += getBlueValue(color);
					}
				}
				outBuff.setRGB(x, y, comRGB((int) (red / area),
						(int) (green / area), (int) (blue / area)));
			}
		}
		return outBuff;
	}

	private static int getRedValue(int rgbValue) {
		return (rgbValue & 0x00ff0000) >> 16;
	}

	private static int getGreenValue(int rgbValue) {
		return (rgbValue & 0x0000ff00) >> 8;
	}

	private static int getBlueValue(int rgbValue) {
		return rgbValue & 0x000000ff;
	}

	private static int comRGB(int redValue, int greenValue, int blueValue) {
		return (redValue << 16) + (greenValue << 8) + blueValue;
	}

	public static void main(String[] args) throws Exception {
		long time = System.currentTimeMillis();
		ImageUtil.resizeFix(new File("E:\\pic\\mark.jpg"), new File("E:\\pic\\mark_2.jpg") , 1/2f);
		ImageUtil.resizeFix(new File("E:\\pic\\mark.jpg"), new File("E:\\pic\\mark_4.jpg") , 1/4f);
		time = System.currentTimeMillis() - time;
		System.out.println("resize2 img in " + time + "ms");
	}

}