这里面包含了一百多个JAVA源文件

				This example implements a method for writing a JPEG file with a specific compression quality. In J2SE 1.4, the compression capability is not functioning properly. This example demonstrates a workaround. 
				    // Reads the jpeg image in infile, compresses the image,
				    // and writes it back out to outfile.
				    // compressionQuality ranges between 0 and 1,
				    // 0-lowest, 1-highest.
				    public void compressJpegFile(File infile, File outfile, float compressionQuality) {
				        try {
				            // Retrieve jpg image to be compressed
				            RenderedImage rendImage = ImageIO.read(infile);
				    
				            // Find a jpeg writer
				            ImageWriter writer = null;
				            Iterator iter = ImageIO.getImageWritersByFormatName("jpg");
				            if (iter.hasNext()) {
				                writer = (ImageWriter)iter.next();
				            }
				    
				            // Prepare output file
				            ImageOutputStream ios = ImageIO.createImageOutputStream(outfile);
				            writer.setOutput(ios);
				    
				            // Set the compression quality
				            ImageWriteParam iwparam = new MyImageWriteParam();
				            iwparam.setCompressionMode(ImageWriteParam.MODE_EXPLICIT) ;
				            iwparam.setCompressionQuality(compressionQuality);
				    
				            // Write the image
				            writer.write(null, new IIOImage(rendImage, null, null), iwparam);
				    
				            // Cleanup
				            ios.flush();
				            writer.dispose();
				            ios.close();
				        } catch (IOException e) {
				        }
				    }
				    
				    // This class overrides the setCompressionQuality() method to workaround
				    // a problem in compressing JPEG images using the javax.imageio package.
				    public class MyImageWriteParam extends JPEGImageWriteParam {
				        public MyImageWriteParam() {
				            super(Locale.getDefault());
				        }
				    
				        // This method accepts quality levels between 0 (lowest) and 1 (highest) and simply converts
				        // it to a range between 0 and 256; this is not a correct conversion algorithm.
				        // However, a proper alternative is a lot more complicated.
				        // This should do until the bug is fixed.
				        public void setCompressionQuality(float quality) {
				            if (quality < 0.0F || quality > 1.0F) {
				                throw new IllegalArgumentException("Quality out-of-bounds!");
				            }
				            this.compressionQuality = 256 - (quality * 256);
				        }
				    }