import java.security.MessageDigest;



/**
* 对密码进行加密和验证的类
*/
public class CipherUtil{

//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 */
public static String generatePassword(String inputString){
return encodeByMD5(inputString);
}

/**
* 验证输入的密码是否正确
* @param password 加密后的密码
* @param inputString 输入的字符串
* @return 验证结果,TRUE:正确 FALSE:错误
*/
public static boolean validatePassword(String password, String inputString){
if(password.equals(encodeByMD5(inputString))){
return true;
} else{
return false;
}
}
/** 对字符串进行MD5加密 */
private static String encodeByMD5(String originString){
if (originString != null){
try{
//创建具有指定算法名称的信息摘要
MessageDigest md = MessageDigest.getInstance("MD5");
//使用指定的字节数组对摘要进行最后更新,然后完成摘要计算
byte[] results = md.digest(originString.getBytes());
//将得到的字节数组变成字符串返回
String resultString = byteArrayToHexString(results);
return resultString.toUpperCase();
} catch(Exception ex){
ex.printStackTrace();
}
}
return null;
}

/**
* 转换字节数组为十六进制字符串
* @param 字节数组
* @return 十六进制字符串
*/
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();
}

/** 将一个字节转化成十六进制形式的字符串 */
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];
}
}

package com.sunnylocus.util;

import java.security.MessageDigest;

/**
* 对密码进行加密和验证的类
*/
public class CipherUtil{

//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 */
public static String generatePassword(String inputString){
return encodeByMD5(inputString);
}

/**
* 验证输入的密码是否正确
* @param password 加密后的密码
* @param inputString 输入的字符串
* @return 验证结果,TRUE:正确 FALSE:错误
*/
public static boolean validatePassword(String password, String inputString){
if(password.equals(encodeByMD5(inputString))){
return true;
} else{
return false;
}
}
/** 对字符串进行MD5加密 */
private static String encodeByMD5(String originString){
if (originString != null){
try{
//创建具有指定算法名称的信息摘要
MessageDigest md = MessageDigest.getInstance("MD5");
//使用指定的字节数组对摘要进行最后更新,然后完成摘要计算
byte[] results = md.digest(originString.getBytes());
//将得到的字节数组变成字符串返回
String resultString = byteArrayToHexString(results);
return resultString.toUpperCase();
} catch(Exception ex){
ex.printStackTrace();
}
}
return null;
}

/**
* 转换字节数组为十六进制字符串
* @param 字节数组
* @return 十六进制字符串
*/
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();
}

/** 将一个字节转化成十六进制形式的字符串 */
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];
}
}

Java代码
package com.sunnylocus.util;

public class Main {
public static void main(String[] args) {
String pwd1="123";
String pwd2="";
CipherUtil cipher = new CipherUtil();
System.out.println("未加密的密码:"+pwd1);
//将123加密
pwd2 = cipher.generatePassword(pwd1);
System.out.println("加密后的密码:"+pwd2);

System.out.print("验证密码是否下确:");
if(cipher.validatePassword(pwd2, pwd1)) {
System.out.println("正确");
}
else {
System.out.println("错误");
}
}
}

package com.sunnylocus.util;

public class Main {
public static void main(String[] args) {
String pwd1="123";
String pwd2="";
CipherUtil cipher = new CipherUtil();
System.out.println("未加密的密码:"+pwd1);
//将123加密
pwd2 = cipher.generatePassword(pwd1);
System.out.println("加密后的密码:"+pwd2);

System.out.print("验证密码是否下确:");
if(cipher.validatePassword(pwd2, pwd1)) {
System.out.println("正确");
}
else {
System.out.println("错误");
}
}
}