java 代码判断图片格式后缀名称

 /**
 * 图片判断
 */
private static String getFormatName(Object o) {
     try {
         // Create an image input stream on the image
         ImageInputStream iis = ImageIO.createImageInputStream(o);  

         // Find all image readers that recognize the image format
         Iterator<ImageReader> iter = ImageIO.getImageReaders(iis);
         if (!iter.hasNext()) {
             // No readers found
             return null;
         }  

         // Use the first reader
         ImageReader reader = (ImageReader) iter.next();  

         // Close stream
         iis.close();  

         // Return the format name
         return reader.getFormatName();
     } catch (IOException e) {
         //
     }

     // The image could not be read
     return null;
 }