获取MD5值

//获取MD5值
	 public static String getMd5ByFile(File file) throws FileNotFoundException {  
         String value = null;  
         FileInputStream in = new FileInputStream(file);  
     try {  
         MappedByteBuffer byteBuffer = in.getChannel().map(FileChannel.MapMode.READ_ONLY, 0, file.length());  
         MessageDigest md5 = MessageDigest.getInstance("MD5");  
         md5.update(byteBuffer);  
         BigInteger bi = new BigInteger(1, md5.digest());  
         value = bi.toString(16);  
     } catch (Exception e) {  
         e.printStackTrace();  
     } finally {  
             if(null != in) {  
                 try {  
                 in.close();  
             } catch (IOException e) {  
                 e.printStackTrace();  
             }  
         }  
     }  
     return value;  
     }