参考资料写了一个生成缩略图的类

写了有一年多了，还是拿出来，以备后用

 

 

package cn.tofishes.util.image;

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

import com.sun.image.codec.jpeg.ImageFormatException;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;
/**
 * 生成图片缩略图
 * @author ToFishes
 *
 */
public class ReduceImage {

	/**
	 * 自定义宽高生成缩略图
	 * @param imgSrc 原图片的绝对路径名
	 * @param imgDist 生成缩略图后的存放绝对路径名
	 * @param widthDist 缩略图的宽度
	 * @param heightDist 缩略图的高度
	 */
	public static void reduceImg(String imgSrc, String imgDist, int widthDist,
			int heightDist) {
		try {
			File srcfile = new File(imgSrc);
			if (!srcfile.exists()) {
				return;
			}
			Image src = javax.imageio.ImageIO.read(srcfile);

			reduceImg(src, imgDist, widthDist, heightDist);

		} catch (IOException ex) {
			ex.printStackTrace();
		}
	}
	/**
	 * 按照图片原有比例生成图片缩略图，maxSize为图片高度、宽度的最大值。
	 * @param imgSrc 原图片的绝对路径
	 * @param imgDist 生成缩略图后的存放绝对路径名
	 * @param maxSize 图片高度、宽度的最大值。
	 */
	public static void reduceImg(String imgSrc, String imgDist, int maxSize) {
		File srcfile = new File(imgSrc);
		if (!srcfile.exists()) {
			return;
		}
		try {
			Image src = javax.imageio.ImageIO.read(srcfile);
			
			float width = src.getWidth(null);
			float height = src.getHeight(null);
			
			/* 获得图片缩放的比例，哪个大就以哪个为标准
			 * 前面的width或height得设置为float类型，否则相除得整型0
			 *  */
			float proportion = width > height ? maxSize/width : maxSize/height;

			int widthDist = Math.round(width*proportion);
			int heightDist = Math.round(height*proportion);

			reduceImg(src, imgDist, widthDist, heightDist);
			
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	}

	public static void reduceImg(Image src, String imgDist, int widthDist,
			int heightDist) throws ImageFormatException, IOException {
		
			if (widthDist <= 0 || heightDist <= 0 ) {
				throw new ImageFormatException("缩略图高宽不能等于小于0");
			}
			BufferedImage tag = new BufferedImage(widthDist, heightDist,
					BufferedImage.TYPE_INT_RGB);

			// tag.getGraphics().drawImage(src.getScaledInstance(widthDist,
			// heightDist, Image.SCALE_SMOOTH), 0, 0, null);
			tag.getGraphics().drawImage(
					src.getScaledInstance(widthDist, heightDist,
							Image.SCALE_AREA_AVERAGING), 0, 0, null);

			FileOutputStream out = new FileOutputStream(imgDist);
			JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
			encoder.encode(tag);
			out.close();
	}
	/**
	 * @param args
	 */
	public static void main(String[] args) {

		String imageSrc = "G:/1218794106_ddvip_459.jpg";
		String imgDist = "G:/1218794106.jpg";
		long start = System.currentTimeMillis();
		ReduceImage.reduceImg(imageSrc, imgDist, 120);
		long end = System.currentTimeMillis();
		System.out.println("耗用时间为:  --  " + (end - start) + "毫秒");
		System.out.println("耗用时间为:  --  " + (end - start) / 1000.0 + "秒");
	}

}