Java 创建图片的缩略图示例

 
void createThumbnail(String filename, int thumbWidth, int thumbHeight, 
             int quality, String outFilename) 
        throws InterruptedException, FileNotFoundException, IOException 
{ 
        // load image from filename 
        Image image = Toolkit.getDefaultToolkit().getImage(filename); 
        MediaTracker mediaTracker = new MediaTracker(new Container()); 
        mediaTracker.addImage(image, 0); 
        mediaTracker.waitForID(0); 
        // use this to test for errors at this point: 
    // System.out.println(mediaTracker.isErrorAny()); 
        // determine thumbnail size from WIDTH and HEIGHT 
        double thumbRatio = (double)thumbWidth / (double)thumbHeight; 
        int imageWidth = image.getWidth(null); 
        int imageHeight = image.getHeight(null); 
        double imageRatio = (double)imageWidth / (double)imageHeight; 
        if (thumbRatio < imageRatio) { 
            thumbHeight = (int)(thumbWidth / imageRatio); 
        } else { 
            thumbWidth = (int)(thumbHeight * imageRatio); 
        } 
    
        // draw original image to thumbnail image object and 
        // scale it to the new size on-the-fly 
        BufferedImage thumbImage = new BufferedImage(thumbWidth, thumbHeight, 
        BufferedImage.TYPE_INT_RGB); 
        Graphics2D graphics2D = thumbImage.createGraphics(); 
        graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION, 
        RenderingHints.VALUE_INTERPOLATION_BILINEAR); 
        graphics2D.drawImage(image, 0, 0, thumbWidth, thumbHeight, null); 
  
        // save thumbnail image to outFilename 
        BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(outFilename)); 
        JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out); 
        JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam(thumbImage); 
        quality = Math.max(0, Math.min(quality, 100)); 
        param.setQuality((float)quality / 100.0f, false); 
        encoder.setJPEGEncodeParam(param); 
        encoder.encode(thumbImage); 
        out.close(); 
}

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