CyberJos is Blogging.

有興趣的不妨看看：http://www.mindprod.com/unmain.html

不過重點是，學它要做啥？我只想到兩個理由：

• 一、如果你不想讓別人輕易地 trace 你的程式碼時，可以依照這本手冊來做。對我來說，玩的都是 open source 的東西，也不怕被 trace，甚至希望大家一起來 trace。所以可能用在公司裡，防同事和老闆會比較有用吧。
• 二、置之死地而後生。學會之後，就可以去想辦法避免寫出這樣的程式碼。雖然程式碼並不一定會變的比較好維護，但至少維護起來不會太困難。

/** * Image utility. * * @author Joseph Kuo * @since */ import java.awt.Graphics2D; import java.awt.image.BufferedImage; import java.awt.image.ColorModel; import java.awt.image.WritableRaster; import java.io.File; import java.io.IOException; import javax.imageio.ImageIO; public class ImageUtils { public static final String JPEG_SUFFIX_1 = "jpg"; public static final String JPEG_SUFFIX_2 = "jpeg"; public static final String PNG_SUFFIX = "png"; public static final String GIF_SUFFIX = "gif"; public static final String[] IMAGE_SUFFIXES = { PNG_SUFFIX, GIF_SUFFIX, JPEG_SUFFIX_1, JPEG_SUFFIX_2 }; // Check if the name of the given file has image format suffix. public static boolean isImage(File file) { return file != null && isImageFilename(file.getName()); } // Check if the given name has image format suffix. public static boolean isImageFilename(String filename) { if (filename == null || filename.length() < 1) { return false; } // Check if it has '.' int index = filename.lastIndexOf("."); if (-1 == index) { return false; } // Check the extension. String filenameExt = filename.substring(index + 1); for (String ext : IMAGE_SUFFIXES) { if (ext.equalsIgnoreCase(filenameExt)) { return true; } } return false; } // width: target width, height: target height. public static boolean scaleImage(File source, File target, int width, int height) { // Check if source is an image and readable. if (!isImage(source)) { return false; } BufferedImage bImage = null; try { bImage = ImageIO.read(source); } catch (IOException ex) { } if (null == bImage) { return false; } // Set right width and height. int sWidth = bImage.getWidth(); int sHeight = bImage.getHeight(); if (width <= 0 && height <= 0) { width = sWidth; height = sHeight; } else if (width <= 0) { width = (int) ((double) sWidth * height / sHeight); } else if (height <= 0) { height = (int) ((double) sHeight * width / sWidth); } // Prepare the target image environment. BufferedImage bImage2 = null; if (bImage.getType() != BufferedImage.TYPE_CUSTOM) { bImage2 = new BufferedImage(width, height, bImage.getType()); Graphics2D g2d = (Graphics2D) bImage2.getGraphics(); g2d.scale((double) width / sWidth, (double) height / sHeight); g2d.drawImage(bImage, 0, 0, null); g2d.dispose(); } else { ColorModel cm = bImage.getColorModel(); WritableRaster raster = cm.createCompatibleWritableRaster(width, height); boolean alphaPremultiplied = cm.isAlphaPremultiplied(); bImage2 = new BufferedImage(cm, raster, alphaPremultiplied, null); } try { // Get image format. String formatName = source.getName().substring(source.getName().indexOf(".")); // We can not save a file as 'gif', so we save it as 'png'. if (GIF_SUFFIX.equalsIgnoreCase(formatName)) { formatName = PNG_SUFFIX; } // And we also choose the right JPEG format 'jpeg' instand of 'jpg' if (!PNG_SUFFIX.equalsIgnoreCase(formatName)) { formatName = JPEG_SUFFIX_2; } ImageIO.write(bImage2, formatName, target); } catch (IOException ex) { return false; } return true; } }