MD5加密Java工具類

原文：http://www.open-open.com/code/view/1421764946296

 

import java.security.MessageDigest;
public class MD5 {
    //公鹽
    private static final String PUBLIC_SALT = "demo" ;
    //十六進制下數字到字符的映射數組  
    private final static String[] hexDigits = {"0", "1", "2", "3", "4",  
        "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f"};
     
    /**
     * 用戶密碼加密，鹽值為 ：私鹽+公鹽
     * @param  password 密碼
     * @param  salt 私鹽
     * @return  MD5加密字符串
     */
    public static String encryptPassword(String password,String salt){
        return encodeByMD5(PUBLIC_SALT+password+salt);
    }
     
    /**
     * md5加密算法
     * @param  originString
     * @return 
     */
    private static String encodeByMD5(String originString){  
        if (originString != null){  
            try{  
                //創建具有指定算法名稱的信息摘要  
                MessageDigest md = MessageDigest.getInstance("MD5");  
                //使用指定的字節數組對摘要進行最后更新，然后完成摘要計算  
                byte[] results = md.digest(originString.getBytes());  
                //將得到的字節數組變成字符串返回  
                String resultString = byteArrayToHexString(results);  
                return resultString.toUpperCase();  
            } catch(Exception ex){  
                ex.printStackTrace();  
            }  
        }  
        return null;  
    } 
     
    /**  
     * 轉換字節數組為十六進制字符串 
     * @param     字節數組 
     * @return    十六進制字符串 
     */  
    private static String byteArrayToHexString(byte[] b){  
        StringBuffer resultSb = new StringBuffer();  
        for (int i = 0; i < b.length; i++){  
            resultSb.append(byteToHexString(b[i]));  
        }  
        return resultSb.toString();  
    }  
       
    /** 將一個字節轉化成十六進制形式的字符串     */  
    private static String byteToHexString(byte b){  
        int n = b;  
        if (n < 0)  
            n = 256 + n;  
        int d1 = n / 16;  
        int d2 = n % 16;  
        return hexDigits[d1] + hexDigits[d2];  
    }
}