算法

算法 - 随机密码生成算法

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import java.util.Random;/** * Created by 谭健 on 2017/10/16. 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 setter    public 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;                else                    x = puppetLetter + lowercaseIndex;                break;            case 3:                if (levelIndex == 0)                    x = puppetNumber;                else if (levelIndex == index)                    x = puppetLetter + lowercaseIndex;                else                    x = 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;                else                    x = 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());    }}