记录一下，说不定以后什么时候用到， 工具类这种东西能默默写下来的人是真牛逼，我承认我做不到，以后用不到的时候复制过去用就好！
如下： Md5加密工具类：
DigestUtils：
package com.macw.util; import java.io.UnsupportedEncodingException; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; public class DigestUtils { // 获取md5加密算法对象 private final static MessageDigest md; private final static char[] cs = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' }; static { try { md = MessageDigest.getInstance("md5"); } catch (NoSuchAlgorithmException e) { // TODO Auto-generated catch block e.printStackTrace(); throw new RuntimeException(e); } } public static String md5(String text) { try { byte[] bs = md.digest(text.getBytes("utf-8")); StringBuilder sb = new StringBuilder(); for (byte b : bs) { sb.append(cs[(b >> 4) & 0x0f]); sb.append(cs[b & 0x0f]); } return sb.toString(); } catch (UnsupportedEncodingException e) { // TODO Auto-generated catch block e.printStackTrace(); throw new RuntimeException(e); } } //测试 public static void main(String[] args) { System.out.println(md5("hello world")); System.out.println(md5("hello world")); System.out.println(md5("hello_world")); System.out.println(md5("hello_world")); } }