MD5的加密和验证

package com.ysj.test;

import java.security.MessageDigest;

/**
* 对密码进行加密和验证的程序
*/
public class Md5 {

/** 十六进制下数字到字符的映射数组 */
private final static String[] hexDigits = { "0", "1", "2", "3", "4", "5",
"6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };

/**
* 把inputString加密。
*
* @param inputString
*            待加密的字符串
* @return
*/
public static String createPassword(String inputString) {
return encodeByMD5(inputString);
}

/**
* 验证输入的密码是否正确
*
* @param password
*            真正的密码（加密后的真密码）
* @param inputString
*            输入的字符串
* @return
*/
public static boolean authenticatePassword(String password,
String inputString) {
if (password.equals(encodeByMD5(inputString))) {
return true;
} else {
return false;
}
}

/**
* 对字符串进行MD5编码
*
* @param originString
* @return
*/
private static String encodeByMD5(String originString) {
if (originString != null) {
try {
MessageDigest md = MessageDigest.getInstance("MD5");
byte[] results = md.digest(originString.getBytes());
String resultString = byteArrayToHexString(results);
return resultString.toUpperCase();
} catch (Exception ex) {
ex.printStackTrace();
}
}
return null;
}

/**
* 转换字节数组为16进制字串
*
* @param b
*            字节数组
* @return 十六进制字串
*/
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();
}

/**
* 将一个字节转化成16进制形式的字符串
*
* @param b
* @return
*/
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];
}

public static void main(String[] args) {
String password = Md5.createPassword("888888");
System.out.println("对888888用MD5摘要后的字符串：" + password);
String inputString = "8888";
System.out.println("8888与密码匹配？"
+ Md5.authenticatePassword(password, inputString));
inputString = "888888";
System.out.println("888888与密码匹配？"
+ Md5.authenticatePassword(password, inputString));
}
}


来源： http://yuncode.net/code/c_50b460ae6791910