java上传图片放大（小图等比放大，大图等比裁剪）

import java.awt.Graphics; 
import java.awt.Image; 
import java.awt.image.BufferedImage; 
import java.io.File; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import javax.imageio.ImageIO; 
   
import com.sun.image.codec.jpeg.JPEGCodec; 
import com.sun.image.codec.jpeg.JPEGImageEncoder; 
   
/**
 * 上传图片-小图片放大图片不变型，但会模糊(取决于图片本身的像素)
 * 
 * @author sunlight
 * 
 */ 
public class AmplificationImage { 
   
    /**
     * 判断图片是否大于目标尺寸
     * 
     * @param srcPath
     * @param maxWidth
     * @param maxHeight
     * @return
     */ 
    public static boolean isBigImage(String srcPath, int maxWidth, int maxHeight) { 
        BufferedImage bufferedImage = null; 
        try { 
            File of = new File(srcPath); 
            if (of.canRead()) { 
                bufferedImage = ImageIO.read(of); 
            } 
        } catch (Exception e) { 
            return false; 
        } 
        if (bufferedImage != null) { 
            int width = bufferedImage.getWidth(); 
            int height = bufferedImage.getHeight(); 
            if (width > maxWidth && height > maxHeight) { 
                return true; 
            } 
        } 
        return false; 
    } 
   
    /**
     * 图片放大的方法（不会变色）
     * @param inputUrl 图片输入路劲
     * @param outputUrl 图片输出路劲
     * @param maxWidth 目标宽
     * @param maxHeight 目标高
     * @param proportion 是否等比缩放
     * @return
     */ 
    public static boolean zoomPicture(String inputUrl, String outputUrl, 
            int maxWidth, int maxHeight, boolean proportion) { 
        try { 
            // 获得源文件 
            File file = new File(inputUrl); 
            if (!file.exists()) { 
                return false; 
            } 
            Image img = ImageIO.read(file); 
            // 判断图片格式是否正确 
            if (img.getWidth(null) == -1) { 
                return false; 
            } else { 
                int newWidth; 
                int newHeight; 
                // 判断是否是等比缩放 
                if (proportion == true) { 
                    // 为等比缩放计算输出的图片宽度及高度 
                    double rate1 = ((double) img.getWidth(null)) 
                            / (double) maxWidth; 
                    double rate2 = ((double) img.getHeight(null)) 
                            / (double) maxHeight; 
                    // 根据缩放比率大的进行缩放控制 
                    double rate = rate1 > rate2 ? rate2 : rate1; 
                    newWidth = (int) (((double) img.getWidth(null)) / rate); 
                    newHeight = (int) (((double) img.getHeight(null)) / rate); 
                } else { 
                    newWidth = maxWidth; // 输出的图片宽度 
                    newHeight = maxHeight; // 输出的图片高度 
                } 
                BufferedImage tag = new BufferedImage((int) newWidth, 
                        (int) newHeight, BufferedImage.TYPE_INT_RGB); 
   
                tag.getGraphics().drawImage( 
                        img.getScaledInstance(newWidth, newHeight, 
                                Image.SCALE_SMOOTH), 0, 0, null); 
                FileOutputStream out = new FileOutputStream(outputUrl); 
                // JPEGImageEncoder可适用于其他图片类型的转换 
                JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out); 
                encoder.encode(tag); 
                out.close(); 
            } 
        } catch (Exception e) { 
            e.printStackTrace(); 
        } 
        return true; 
    } 
       
    /**
     * 对图片进行放大（部分图片会变红）
     * @param srcPath
     *            原始图片路径(绝对路径)
     * @param newPath
     *            放大后图片路径（绝对路径）
     * @param times
     *            放大倍数
     * @return 是否放大成功
     */ 
   
    public static boolean zoomInImage(String srcPath, String newPath, 
            int maxWidth, int maxHeight) { 
        BufferedImage bufferedImage = null; 
        try { 
            File of = new File(srcPath); 
            if (of.canRead()) { 
                bufferedImage = ImageIO.read(of); 
            } 
        } catch (IOException e) { 
            // TODO: 打印日志 
            return false; 
        } 
        if (bufferedImage != null) { 
            bufferedImage = zoomInImage(bufferedImage, maxWidth, maxHeight); 
            try { 
                // TODO: 这个保存路径需要配置下子好一点 
                ImageIO.write(bufferedImage, "JPG", new File(newPath)); // 保存修改后的图像,全部保存为JPG格式 
            } catch (IOException e) { 
                // TODO 打印错误信息 
                return false; 
            } 
        } 
        return true; 
    } 
   
    /**
     * 对图片进行放大
     * 
     * @param originalImage
     *            原始图片
     * @param maxWidth
     *            目标宽度
     * @param maxHeight
     *            目标高度
     * @return
     */ 
    private static BufferedImage zoomInImage(BufferedImage originalImage, 
            int maxWidth, int maxHeight) { 
        int times = 1; // 放大倍数 
        int width = originalImage.getWidth(); 
        int height = originalImage.getHeight(); 
        double sw = (maxWidth * 1.0) / (width * 1.0); 
        double sh = (maxHeight * 1.0) / (height * 1.0); 
        if (width > maxWidth && height > maxHeight) { 
            return originalImage; 
        } else if (width < maxWidth && height < maxHeight) { 
            if (sw > sh) { 
                times = (int) (sw + 0.8); 
            } else { 
                times = (int) (sh + 0.8); 
            } 
        } else if (width < maxWidth && height > maxHeight) { 
            times = (int) (sw + 0.8); 
        } else { 
            times = (int) (sh + 0.8); 
        } 
        int lastW = times * width; 
        int lastH = times * height; 
        BufferedImage newImage = new BufferedImage(lastW, lastH, originalImage 
                .getType()); 
        Graphics g = newImage.getGraphics(); 
        g.drawImage(originalImage, 0, 0, lastW, lastH, null); 
        g.dispose(); 
        return newImage; 
    } 
}