Swing图片处理工具类ImageHelper

package zju.archeo.images;import java.awt.Color;import java.awt.Graphics2D;import java.awt.Image;import java.awt.Toolkit;import java.awt.image.BufferedImage;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.net.URL;import javax.imageio.ImageIO;import javax.swing.ImageIcon;import com.sun.image.codec.jpeg.JPEGCodec;import com.sun.image.codec.jpeg.JPEGEncodeParam;import com.sun.image.codec.jpeg.JPEGImageEncoder;public class ImageHelper {public static ImageIcon loadImage(String name) {ImageIcon image = null;try {URL url = ImageHelper.class.getResource(name);if (url != null) {Image img = Toolkit.getDefaultToolkit().createImage(url);if (img != null)image = new ImageIcon(img);}} catch (Throwable ex) {System.out.println("ERROR: loading image " + name+ " failed. Exception: " + ex.getMessage());}return image;}public static ImageIcon loadLocalImage(String path) {return new ImageIcon(path);}/** *  * @param dir  *            图片所在的文件夹路径,以路径分隔符结尾 * @param name *            图片文件名，包括扩展名 * @param smName *            输出文件名，包括扩展名 * @param n *            图片名 * @param width *            目标宽 * @param height *            目标高 * @param per *            压缩百分比 */public static void compressPic(String dir, String name, String smName, int width, int height, double per){try {File file = new File(dir+name);Image src = ImageIO.read(file); // 构造Image对象int old_w = src.getWidth(null); // 得到源图宽int old_h = src.getHeight(null);// 得到源图高// 图片跟据长宽留白，成一个正方形图。BufferedImage oldpic;if (old_w > old_h) {oldpic = new BufferedImage(old_w, old_w,BufferedImage.TYPE_INT_RGB);}else if(old_w < old_h) {oldpic = new BufferedImage(old_h, old_h,BufferedImage.TYPE_INT_RGB);}else{oldpic = new BufferedImage(old_w, old_h,BufferedImage.TYPE_INT_RGB);}Graphics2D g = oldpic.createGraphics();g.setColor(Color.white);if (old_w > old_h) {g.fillRect(0, 0, old_w, old_w);g.drawImage(src, 0, (old_w - old_h) / 2, old_w, old_h,Color.white, null);}else if(old_w < old_h) {g.fillRect(0, 0, old_h, old_h);g.drawImage(src, (old_h - old_w) / 2, 0, old_w, old_h,Color.white, null);}else{// g.fillRect(0,0,old_h,old_h);g.drawImage(src.getScaledInstance(old_w, old_h,Image.SCALE_SMOOTH), 0, 0, null);}g.dispose();src = oldpic;// 图片调整为方形结束int new_w = 0, new_h = 0; double w2 = (old_w * 1.00) / (width * 1.00);double h2 = (old_h * 1.00) / (height * 1.00);if(old_w > width)new_w = (int) Math.round(old_w / w2);elsenew_w = old_w;if(old_h > height)new_h = (int) Math.round(old_h / h2);// 计算新图长宽elsenew_h = old_h;BufferedImage tag = new BufferedImage(new_w, new_h,BufferedImage.TYPE_INT_RGB);// tag.getGraphics().drawImage(src,0,0,new_w,new_h,null); //绘制缩小后的图tag.getGraphics().drawImage(src.getScaledInstance(new_w, new_h, Image.SCALE_SMOOTH), 0,0, null);FileOutputStream newimage = new FileOutputStream(dir+smName); // 输出到文件流JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(newimage);JPEGEncodeParam jep = JPEGCodec.getDefaultJPEGEncodeParam(tag);jep.setQuality((float) per, true); // 压缩质量 encoder.encode(tag, jep);// encoder.encode(tag); //近JPEG编码newimage.close();} catch (IOException ex) {ex.printStackTrace();}}/** * 根据路径名和文件名获取小图片，返回小图片路径 * @param dir * 图片路径，以分隔符结束 * @param name * 图片名，最好包含扩展名 * @return * 缩小后的图片路径，以jpg为扩展名，默认大小45*45，压缩率0.7 */public static String getSmallImage(String dir, String name){String trueName = name, ext = "";int pos = name.lastIndexOf('.');if(pos != -1){ //包含扩展名trueName = name.substring(0, pos);ext = name.substring(pos); //包含.}String smallName = trueName+"_small"+ext;compressPic(dir, name, smallName, 45, 45, 0.7);return dir+smallName;} public static void main(String args[]){  getSmallImage("tmp"+File.separator, "Koala.jpg"); } }