java的MD5加密

/**
	 * MD5加密
	 * @param plainText
	 * @return
	 */
	public String Md5(String plainText) { 
			String md5="";
			try {
				MessageDigest md = MessageDigest.getInstance("MD5"); 
				md.update(plainText.getBytes()); 
				byte b[] = md.digest(); 

				int i; 

				StringBuffer buf = new StringBuffer(""); 
				for (int offset = 0; offset < b.length; offset++) { 
				i = b[offset]; 
				if(i<0) i+= 256; 
				if(i<16) 
				buf.append("0"); 
				buf.append(Integer.toHexString(i)); 
				} 
				//返回32位加密
				md5=buf.toString();
			} catch (NoSuchAlgorithmException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			return md5; 
		}