图片工具类，完成图片的截取,缩放(ImageHepler )

package com.lz.hr_picture.helper;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.RenderingHints;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.awt.image.ColorModel;
import java.awt.image.WritableRaster;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import javax.imageio.ImageIO;


/**
 * 图片工具类，完成图片的截取
 *
 * @author penghuaiyi
 * @date 2010-11-10
 */
public class ImageHepler {
    /**
     * 实现图像的等比缩放
     * @param source
     * @param targetW
     * @param targetH
     * @return
     */
    private static BufferedImage resize(BufferedImage source, int targetW,
            int targetH) {
        // targetW，targetH分别表示目标长和宽
        int type = source.getType();
        BufferedImage target = null;
        double sx = (double) targetW / source.getWidth();
        double sy = (double) targetH / source.getHeight();
        // 这里想实现在targetW，targetH范围内实现等比缩放。如果不需要等比缩放
        // 则将下面的if else语句注释即可
        if (sx < sy) {
            sx = sy;
            targetW = (int) (sx * source.getWidth());
        } else {
            sy = sx;
            targetH = (int) (sy * source.getHeight());
        }
        if (type == BufferedImage.TYPE_CUSTOM) { // handmade
            ColorModel cm = source.getColorModel();
            WritableRaster raster = cm.createCompatibleWritableRaster(targetW,
                    targetH);
            boolean alphaPremultiplied = cm.isAlphaPremultiplied();
            target = new BufferedImage(cm, raster, alphaPremultiplied, null);
        } else
            target = new BufferedImage(targetW, targetH, type);
        Graphics2D g = target.createGraphics();
        // smoother than exlax:
        g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
                RenderingHints.VALUE_INTERPOLATION_BICUBIC);
        g.drawRenderedImage(source, AffineTransform.getScaleInstance(sx, sy));
        g.dispose();
        return target;
    }

    /**
     * 实现图像的等比缩放和缩放后的截取
     * @param inFilePath 要截取文件的路径
     * @param outFilePath 截取后输出的路径
     * @param width 要截取宽度
     * @param hight 要截取的高度
     * @param proportion
     * @throws Exception
     */

    public static void saveImageAsJpg(String inFilePath, String outFilePath,
            int width, int hight, boolean proportion)throws Exception {
         File file = new File(inFilePath);
         InputStream in = new FileInputStream(file);
         File saveFile = new File(outFilePath);

        BufferedImage srcImage = ImageIO.read(in);
        if (width > 0 || hight > 0) {
            // 原图的大小
            int sw = srcImage.getWidth();
            int sh = srcImage.getHeight();
            // 如果原图像的大小小于要缩放的图像大小，直接将要缩放的图像复制过去
            if (sw > width && sh > hight) {
                srcImage = resize(srcImage, width, hight);
            } else {
                String fileName = saveFile.getName();
                String formatName = fileName.substring(fileName
                        .lastIndexOf('.') + 1);
                ImageIO.write(srcImage, formatName, saveFile);
                return;
            }
        }
        // 缩放后的图像的宽和高
        int w = srcImage.getWidth();
        int h = srcImage.getHeight();
        // 如果缩放后的图像和要求的图像宽度一样，就对缩放的图像的高度进行截取
        if (w == width) {
            // 计算X轴坐标
            int x = 0;
            int y = h / 2 - hight / 2;
            saveSubImage(srcImage, new Rectangle(x, y, width, hight), saveFile);
        }
        // 否则如果是缩放后的图像的高度和要求的图像高度一样，就对缩放后的图像的宽度进行截取
        else if (h == hight) {
            // 计算X轴坐标
            int x = w / 2 - width / 2;
            int y = 0;
            saveSubImage(srcImage, new Rectangle(x, y, width, hight), saveFile);
        }
        in.close();
    }
    /**
     * 实现缩放后的截图
     * @param image 缩放后的图像
     * @param subImageBounds 要截取的子图的范围
     * @param subImageFile 要保存的文件
     * @throws IOException
     */
    private static void saveSubImage(BufferedImage image,
            Rectangle subImageBounds, File subImageFile) throws IOException {
        if (subImageBounds.x < 0 || subImageBounds.y < 0
                || subImageBounds.width - subImageBounds.x > image.getWidth()
                || subImageBounds.height - subImageBounds.y > image.getHeight()) {
            System.out.println("Bad   subimage   bounds");
            return;
        }
        BufferedImage subImage = image.getSubimage(subImageBounds.x,subImageBounds.y, subImageBounds.width, subImageBounds.height);
        String fileName = subImageFile.getName();
        String formatName = fileName.substring(fileName.lastIndexOf('.') + 1);
        ImageIO.write(subImage, formatName, subImageFile);
    }

    public static void main(String[] args)throws Exception{
    	ImageHepler.saveImageAsJpg("E:\\证书图片\\1.jpg", "E:\\pics\\1.jpg", 600, 400, true);
    }


}