java图片放大缩小 java怎么把图片等比例缩小

package mytiny.com.common;
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;import javax.imageio.ImageIO;
public class ImageZipUtil {
    public static void main(String[] args) {
zipWidthHeightImageFile(new File("D:\\3.png"), new File("D:\\3.png"), 375, 180, 0.8f);        // System.out.println("ok");
    }    /**
     * 根据设置的宽高等比例压缩图片文件<br>
     * 先保存原文件，再压缩、上传
     * 
     * @param oldFile
     *            要进行压缩的文件
     * @param newFile
     *            新文件
     * @param width
     *            宽度 //设置宽度时（高度传入0，等比例缩放）
     * @param height
     *            高度 //设置高度时（宽度传入0，等比例缩放）
     * @param quality
     *            质量
     * @return 返回压缩后的文件的全路径
     */
    public static String zipImageFile(File oldFile, File newFile, int width, int height, float quality) {
        if (oldFile == null) {
            return null;
        }
        try {
            /** 对服务器上的临时文件进行处理 */
            Image srcFile = ImageIO.read(oldFile);
            int w = srcFile.getWidth(null);
            int h = srcFile.getHeight(null);
            double bili;
            if (width > 0) {
                bili = width / (double) w;
                height = (int) (h * bili);
            } else {
                if (height > 0) {
                    bili = height / (double) h;
                    width = (int) (w * bili);
                }
            }            String srcImgPath = newFile.getAbsoluteFile().toString();
            // System.out.println(srcImgPath);
            String subfix = "jpg";
            subfix = srcImgPath.substring(srcImgPath.lastIndexOf(".") + 1, srcImgPath.length());            BufferedImage buffImg = null;
            if (subfix.equals("png")) {
                buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
            } else {
                buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
            }            Graphics2D graphics = buffImg.createGraphics();
            graphics.setBackground(new Color(255, 255, 255));
            graphics.setColor(new Color(255, 255, 255));
            graphics.fillRect(0, 0, width, height);
            graphics.drawImage(srcFile.getScaledInstance(width, height, Image.SCALE_SMOOTH), 0, 0, null);            ImageIO.write(buffImg, subfix, new File(srcImgPath));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return newFile.getAbsolutePath();
    }    /**
     * 按设置的宽度高度压缩图片文件<br>
     * 先保存原文件，再压缩、上传
     * 
     * @param oldFile
     *            要进行压缩的文件全路径
     * @param newFile
     *            新文件
     * @param width
     *            宽度
     * @param height
     *            高度
     * @param quality
     *            质量
     * @return 返回压缩后的文件的全路径
     */
    public static boolean zipWidthHeightImageFile(File oldFile, File newFile, int width, int height, float quality) {
        if (oldFile == null) {
            return false;
        }
        Image srcFile = null;
        BufferedImage buffImg = null;
        try {
            /** 对服务器上的临时文件进行处理 */
            srcFile = ImageIO.read(oldFile);            String srcImgPath = newFile.getAbsoluteFile().toString();
            // System.out.println(srcImgPath);
            String subfix = "jpg";
            subfix = srcImgPath.substring(srcImgPath.lastIndexOf(".") + 1, srcImgPath.length());            if (subfix.equals("png")) {
                buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
            } else {
                buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
            }            Graphics2D graphics = buffImg.createGraphics();
            graphics.setBackground(new Color(255, 255, 255));
            graphics.setColor(new Color(255, 255, 255));
            graphics.fillRect(0, 0, width, height);
            graphics.drawImage(srcFile.getScaledInstance(width, height, Image.SCALE_SMOOTH), 0, 0, null);            ImageIO.write(buffImg, subfix, new File(srcImgPath));
            return true;        } catch (Exception e) {
            e.printStackTrace();
            return false;
        } finally {
            if (srcFile != null) {
                srcFile.flush();
            }
            if (buffImg != null) {
                buffImg.flush();
            }        }
    }
}

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