Java 的 MD5 加密——Java自带的 MD5 加密

转载自：http://blog.sina.com.cn/s/blog_6b275753010161t3.html

利用Java自带的MD5加密

package test.md5;

import java.security.MessageDigest;

public class MD5Util {

    public final static String MD5(String s) {

        char hexDigits[]={'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};       

        try {

            byte[] btInput = s.getBytes();

            // 获得MD5摘要算法的 MessageDigest 对象

            MessageDigest mdInst = MessageDigest.getInstance("MD5");

            // 使用指定的字节更新摘要

            mdInst.update(btInput);

            // 获得密文

            byte[] md = mdInst.digest();

            // 把密文转换成十六进制的字符串形式

            int j = md.length;

            char str[] = new char[j * 2];

            int k = 0;

            for (int i = 0; i < j; i++) {

                byte byte0 = md[i];

                str[k++] = hexDigits[byte0 >>> 4 & 0xf];

                str[k++] = hexDigits[byte0 & 0xf];

            }

            return new String(str);

        } catch (Exception e) {

            e.printStackTrace();

            return null;

        }

    }

    public static void main(String[] args) {

        System.out.println(MD5Util.MD5("20121221"));

        System.out.println(MD5Util.MD5("加密"));

    }

}