Java 工具类 字符串转MD5串

package com.arjun;import java.security.MessageDigest;import java.security.NoSuchAlgorithmException;/** * Created by Arjun on 2017/4/6. */public class MD5Tools {    public static void main(String[] args) {        String test = MD5("test");        System.out.println(test);    }    private static String MD5(String sourceStr) {        String result = "NULL";        try {            MessageDigest md = MessageDigest.getInstance("MD5");            md.update(sourceStr.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));            }            result = buf.toString();            System.out.println("MD5(" + sourceStr + ",32 小写) = " + result.toLowerCase());            System.out.println("MD5(" + sourceStr + ",32 大写) = " + result.toUpperCase());            System.out.println("MD5(" + sourceStr + ",16 小写) = " + buf.toString().substring(8, 24).toLowerCase());            System.out.println("MD5(" + sourceStr + ",16 大写) = " + buf.toString().substring(8, 24).toUpperCase());        } catch (NoSuchAlgorithmException e) {            System.out.println(e);        }        return result;    }}