大型网站对图片的下载，存放，及压缩管理

大型网站对图片的下载，存放，及压缩管理

 

构建保存图片的路径：

1 String pathdir = "/images/product/"+ productTypeId+ "/"+ productId+ "/prototype";//构建文件保存的目录  

为什么要有那么多个目录，因为java本身不会去获取图片，而是调用了操作系统的一些接口来获取图片，如果一个目录下图片太多的话，操作系统获取图片的速度会变慢 ，所以巴巴运动网在构建图片路径的时候搞了多个目录，分散保存图片。

有了这个pathdir就可以得到图片保存目录的真实路径：

1 String realpathdir = request.getSession().getServletContext().getRealPath(pathdir);

获取了图片的真实路径后，就可以开始保存图片了： 

1 File savedir = new File(realpathdir);
2 File file = saveFile(savedir, filename, imagefile.getFileData());

imagefile为struts的FormFile类的对象，filename为文件名，这两个属性都可以从前台获取过来。以下是saveFile方法的代码： 

 1 /**
 2      * 保存文件
 3      * @param savedir 存放目录
 4      * @param fileName 文件名称
 5      * @param data 保存的内容
 6      * @return 保存的文件
 7      * @throws Exception
 8 */
 9 public static File saveFile(File savedir, String fileName, byte[] data) throws Exception{
10 if(!savedir.exists()) savedir.mkdirs();//如果目录不存在就创建
11 File file = new File(savedir, fileName);
12 FileOutputStream fileoutstream = new FileOutputStream(file);
13 fileoutstream.write(data);
14 fileoutstream.close();
15 return file;
16 }

保存完图片后还要保存一张图片的缩略图，宽度为140px 

这里我们用到了一个从网上下的用于压缩图片的ImageSizer工具类的静态方法，resize方法传进去的四个参数分别代表原始图片对象，需要被压缩的图片对象，压缩宽度的大小，图片后缀名。这个工具类只能压缩jpg, png, gif(非动画)三种格式，如果想压缩更多的格式需要付费。以下是该工具类： 

  1 /**
  2  * 图像压缩工具
  3  * @author lihuoming@sohu.com
  4  *
  5 */
  6 public class ImageSizer {
  7 public static final MediaTracker tracker = new MediaTracker(new Component() {
  8 private static final long serialVersionUID = 1234162663955668507L;} 
  9 );
 10 /**
 11      * @param originalFile 原图像
 12      * @param resizedFile 压缩后的图像
 13      * @param width 图像宽
 14      * @param format 图片格式 jpg, png, gif(非动画)
 15      * @throws IOException
 16 */
 17 public static void resize(File originalFile, File resizedFile, int width, String format) throws IOException {
 18 if(format!=null && "gif".equals(format.toLowerCase())){
 19 resize(originalFile, resizedFile, width, 1);
 20 return;
 21 }
 22 FileInputStream fis = new FileInputStream(originalFile);
 23 ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
 24 int readLength = -1;
 25 int bufferSize = 1024;
 26 byte bytes[] = new byte[bufferSize];
 27 while ((readLength = fis.read(bytes, 0, bufferSize)) != -1) {
 28 byteStream.write(bytes, 0, readLength);
 29 }
 30 byte[] in = byteStream.toByteArray();
 31 fis.close();
 32 byteStream.close();
 33 
 34 Image inputImage = Toolkit.getDefaultToolkit().createImage( in );
 35 waitForImage( inputImage );
 36 int imageWidth = inputImage.getWidth( null );
 37 if ( imageWidth < 1 ) 
 38 throw new IllegalArgumentException( "image width " + imageWidth + " is out of range" );
 39 int imageHeight = inputImage.getHeight( null );
 40 if ( imageHeight < 1 ) 
 41 throw new IllegalArgumentException( "image height " + imageHeight + " is out of range" );
 42 
 43 // Create output image.
 44 int height = -1;
 45 double scaleW = (double) imageWidth / (double) width;
 46 double scaleY = (double) imageHeight / (double) height;
 47 if (scaleW >= 0 && scaleY >=0) {
 48 if (scaleW > scaleY) {
 49 height = -1;
 50 } else {
 51 width = -1;
 52 }
 53 }
 54 Image outputImage = inputImage.getScaledInstance( width, height, java.awt.Image.SCALE_DEFAULT);
 55 checkImage( outputImage ); 
 56 encode(new FileOutputStream(resizedFile), outputImage, format); 
 57 } 
 58 
 59 /** Checks the given image for valid width and height. */
 60 private static void checkImage( Image image ) {
 61 waitForImage( image );
 62 int imageWidth = image.getWidth( null );
 63 if ( imageWidth < 1 ) 
 64 throw new IllegalArgumentException( "image width " + imageWidth + " is out of range" );
 65 int imageHeight = image.getHeight( null );
 66 if ( imageHeight < 1 ) 
 67 throw new IllegalArgumentException( "image height " + imageHeight + " is out of range" );
 68 }
 69 
 70 /** Waits for given image to load. Use before querying image height/width/colors. */
 71 private static void waitForImage( Image image ) {
 72 try {
 73 tracker.addImage( image, 0 );
 74 tracker.waitForID( 0 );
 75 tracker.removeImage(image, 0);
 76 } catch( InterruptedException e ) { e.printStackTrace(); }
 77 } 
 78 
 79 /** Encodes the given image at the given quality to the output stream. */
 80 private static void encode( OutputStream outputStream, Image outputImage, String format ) 
 81 throws java.io.IOException {
 82 int outputWidth = outputImage.getWidth( null );
 83 if ( outputWidth < 1 ) 
 84 throw new IllegalArgumentException( "output image width " + outputWidth + " is out of range" );
 85 int outputHeight = outputImage.getHeight( null );
 86 if ( outputHeight < 1 ) 
 87 throw new IllegalArgumentException( "output image height " + outputHeight + " is out of range" );
 88 
 89 // Get a buffered image from the image.
 90 BufferedImage bi = new BufferedImage( outputWidth, outputHeight,
 91 BufferedImage.TYPE_INT_RGB ); 
 92 Graphics2D biContext = bi.createGraphics();
 93 biContext.drawImage( outputImage, 0, 0, null );
 94 ImageIO.write(bi, format, outputStream);
 95 outputStream.flush(); 
 96 } 
 97 
 98 /**
 99      * 缩放gif图片
100      * @param originalFile 原图片
101      * @param resizedFile 缩放后的图片
102      * @param newWidth 宽度
103      * @param quality 缩放比例 (等比例)
104      * @throws IOException
105 */
106 private static void resize(File originalFile, File resizedFile, int newWidth, float quality) throws IOException {
107 if (quality < 0 || quality > 1) {
108 throw new IllegalArgumentException("Quality has to be between 0 and 1");
109 } 
110 ImageIcon ii = new ImageIcon(originalFile.getCanonicalPath());
111 Image i = ii.getImage();
112 Image resizedImage = null; 
113 int iWidth = i.getWidth(null);
114 int iHeight = i.getHeight(null); 
115 if (iWidth > iHeight) {
116 resizedImage = i.getScaledInstance(newWidth, (newWidth * iHeight) / iWidth, Image.SCALE_SMOOTH);
117 } else {
118 resizedImage = i.getScaledInstance((newWidth * iWidth) / iHeight, newWidth, Image.SCALE_SMOOTH);
119 } 
120 // This code ensures that all the pixels in the image are loaded.
121 Image temp = new ImageIcon(resizedImage).getImage(); 
122 // Create the buffered image.
123 BufferedImage bufferedImage = new BufferedImage(temp.getWidth(null), temp.getHeight(null),
124 BufferedImage.TYPE_INT_RGB); 
125 // Copy image to buffered image.
126 Graphics g = bufferedImage.createGraphics(); 
127 // Clear background and paint the image.
128 g.setColor(Color.white);
129 g.fillRect(0, 0, temp.getWidth(null), temp.getHeight(null));
130 g.drawImage(temp, 0, 0, null);
131 g.dispose(); 
132 // Soften.
133 float softenFactor = 0.05f;
134 float[] softenArray = {0, softenFactor, 0, softenFactor, 1-(softenFactor*4), softenFactor, 0, softenFactor, 0};
135 Kernel kernel = new Kernel(3, 3, softenArray);
136 ConvolveOp cOp = new ConvolveOp(kernel, ConvolveOp.EDGE_NO_OP, null);
137 bufferedImage = cOp.filter(bufferedImage, null); 
138 // Write the jpeg to a file.
139 FileOutputStream out = new FileOutputStream(resizedFile); 
140 // Encodes image as a JPEG data stream
141 JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out); 
142 JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam(bufferedImage); 
143 param.setQuality(quality, true); 
144 encoder.setJPEGEncodeParam(param);
145 encoder.encode(bufferedImage);
146 }
147 }