java中压缩图片的代码辅助类

package cn.com.images; import java.awt.Graphics; import java.awt.Image; import java.awt.image.BufferedImage; import java.io.File; import java.io.IOException; import java.math.BigDecimal; import java.math.MathContext; import java.util.ArrayList; import javax.imageio.ImageIO; /*** * 对图片进行操作 * * @author chenzheng_java * @since 2011/7/29 * */ public class ImageHelper { private static ImageHelper imageHelper = null; public static ImageHelper getImageHelper() { if (imageHelper == null) { imageHelper = new ImageHelper(); } return imageHelper; } /*** * 按指定的比例缩放图片 * * @param sourceImagePath * 源地址 * @param destinationPath * 改变大小后图片的地址 * @param scale * 缩放比例，如1.2 */ public static void scaleImage(String sourceImagePath, String destinationPath, double scale,String format) { File file = new File(sourceImagePath); BufferedImage bufferedImage; try { bufferedImage = ImageIO.read(file); int width = bufferedImage.getWidth(); int height = bufferedImage.getHeight(); width = parseDoubleToInt(width * scale); height = parseDoubleToInt(height * scale); Image image = bufferedImage.getScaledInstance(width, height, Image.SCALE_SMOOTH); BufferedImage outputImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics graphics = outputImage.getGraphics(); graphics.drawImage(image, 0, 0, null); graphics.dispose(); ImageIO.write(outputImage, format, new File(destinationPath)); } catch (IOException e) { System.out.println("scaleImage方法压缩图片时出错了"); e.printStackTrace(); } } /*** * 将图片缩放到指定的高度或者宽度 * @param sourceImagePath 图片源地址 * @param destinationPath 压缩完图片的地址 * @param width 缩放后的宽度 * @param height 缩放后的高度 * @param auto 是否自动保持图片的原高宽比例 * @param format 图图片格式 例如 jpg */ public static void scaleImageWithParams(String sourceImagePath, String destinationPath, int width, int height, boolean auto,String format) { try { File file = new File(sourceImagePath); BufferedImage bufferedImage = null; bufferedImage = ImageIO.read(file); if (auto) { ArrayList<Integer> paramsArrayList = getAutoWidthAndHeight(bufferedImage,width,height); width = paramsArrayList.get(0); height = paramsArrayList.get(1); System.out.println("自动调整比例，width="+width+" height="+height); } Image image = bufferedImage.getScaledInstance(width, height, Image.SCALE_DEFAULT); BufferedImage outputImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics graphics = outputImage.getGraphics(); graphics.drawImage(image, 0, 0, null); graphics.dispose(); ImageIO.write(outputImage, format, new File(destinationPath)); } catch (Exception e) { System.out.println("scaleImageWithParams方法压缩图片时出错了"); e.printStackTrace(); } } /** * 将double类型的数据转换为int，四舍五入原则 * * @param sourceDouble * @return */ private static int parseDoubleToInt(double sourceDouble) { int result = 0; result = (int) sourceDouble; return result; } /*** * * @param bufferedImage 要缩放的图片对象 * @param width_scale 要缩放到的宽度 * @param height_scale 要缩放到的高度 * @return 一个集合，第一个元素为宽度，第二个元素为高度 */ private static ArrayList<Integer> getAutoWidthAndHeight(BufferedImage bufferedImage,int width_scale,int height_scale){ ArrayList<Integer> arrayList = new ArrayList<Integer>(); int width = bufferedImage.getWidth(); int height = bufferedImage.getHeight(); double scale_w =getDot2Decimal( width_scale,width); System.out.println("getAutoWidthAndHeight width="+width + "scale_w="+scale_w); double scale_h = getDot2Decimal(height_scale,height); if (scale_w<scale_h) { arrayList.add(parseDoubleToInt(scale_w*width)); arrayList.add(parseDoubleToInt(scale_w*height)); } else { arrayList.add(parseDoubleToInt(scale_h*width)); arrayList.add(parseDoubleToInt(scale_h*height)); } return arrayList; } /*** * 返回两个数a/b的小数点后三位的表示 * @param a * @param b * @return */ public static double getDot2Decimal(int a,int b){ BigDecimal bigDecimal_1 = new BigDecimal(a); BigDecimal bigDecimal_2 = new BigDecimal(b); BigDecimal bigDecimal_result = bigDecimal_1.divide(bigDecimal_2,new MathContext(4)); Double double1 = new Double(bigDecimal_result.toString()); System.out.println("相除后的double为："+double1); return double1; } }