算法 - 随机密码生成算法

import java.util.Random;/*** Created by 谭健 on /10/16. 11:13.* © All Rights Reserved.*/public class Password {public Password() {}// 提供强度的构造方法public Password(int strengthLevel, int length) {this.strengthLevel = strengthLevel;this.length = length;}/*** Password level config* 1 level : only number* 2 level : number and lowercase letters* 3 level : number , lowercase letters , capital letters* 4 level : number , lowercase letters , capital letters , special characters*/private int strengthLevel = 4;// 需要的密码长度private int length = 6;private static final Random RANDOM = new Random();// getter and setterpublic int getLength() {return length;}public void setLength(int length) {this.length = length;}public int getStrengthLevel() {return strengthLevel;}public void setStrengthLevel(int strengthLevel) {this.strengthLevel = strengthLevel;}// 用char类型是因为char类型效率比数组方式要高// 因为伪随机数random在nextInt()的时候会出现向更小的数偏离的情况，所以用一个randomMax来修正private static final int randomMax = 100000000;// 因为数组下标从0开始private static final int index = 1;// 一共26个字母private static final int numberOfLetter = 26;// ascii码表数字从48开始private static final int nunberIndex = 48;// 数组下标0-9代表10个数字private static final int numberMax = 9;// 大写字母ascii码表从65开始private static final int capitalIndex = 65;// 小写字母ascii码表从65开始private static final int lowercaseIndex = 97;// 特殊字符的起始ascii码表序号取第一个数字private static final int special = 0;// 特殊字符集，第一个数字代表ascii码表序号，第二个代表从这里开始一共使用多少个字符private static final int[][] specialCharacter = {{33, 14}, {58, 6}, {91, 5}, {123, 3}};// 取随机密码public String getRandomPassword() throws Exception {StringBuffer buffer = new StringBuffer();if (length <= 0)throw new Exception("length can not <= 0");for (int i = 0; i < length; i++)buffer.append((char) getNextChar());return buffer.toString();}// 取得下一个ascii编码private int getNextChar() throws Exception {if (strengthLevel < 1 || strengthLevel > 4)throw new Exception("This level is not supported");// ascii编码int x = 0;// 伪字符ascii编码final int puppetLetter = RANDOM.nextInt(randomMax) % numberOfLetter;// 伪数字ascii编码final int puppetNumber = RANDOM.nextInt(randomMax) % numberMax + nunberIndex;// 按照字符等级强度取ascii值final int levelIndex = RANDOM.nextInt(randomMax) % strengthLevel;// 特殊字符的随机集合下标（数组第一维）final int specialType = RANDOM.nextInt(randomMax) % specialCharacter.length;// 特殊字符的ascii编码final int specialInt = RANDOM.nextInt(randomMax) % specialCharacter[specialType][index] + specialCharacter[specialType][special];// 根据密码强度等级获取随机ascii编码switch (strengthLevel) {case 1:x = puppetNumber;break;case 2:if (levelIndex == index)x = puppetNumber;elsex = puppetLetter + lowercaseIndex;break;case 3:if (levelIndex == 0)x = puppetNumber;else if (levelIndex == index)x = puppetLetter + lowercaseIndex;elsex = puppetLetter + capitalIndex;break;case 4:if (levelIndex == 0)x = puppetNumber;else if (levelIndex == index)x = puppetLetter + lowercaseIndex;else if (levelIndex == index * 2)x = puppetLetter + capitalIndex;elsex = specialInt;break;default:}return x;}public static void main(String[] args) {System.out.println(System.currentTimeMillis());Password password = new Password();for (int i = 0; i < 10000; i++)try {System.out.println(password.getRandomPassword());} catch (Exception e) {e.printStackTrace();}System.out.println(System.currentTimeMillis());}}