package com.doumee.core.utils;
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import java.security.SecureRandom;
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import java.util.Locale;
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import java.util.Objects;
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import java.util.Random;
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public class RandomString {
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protected static final String upper = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
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protected static final String lower = upper.toLowerCase(Locale.ROOT);
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protected static final String digits = "0123456789";
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protected static final String alphaNumeric = upper + lower + digits;
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private final Random random;
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private final char[] symbols;
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private final char[] buf;
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public RandomString(int length, Random random, String symbols) {
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if (length < 1) {
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throw new IllegalArgumentException();
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}
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if (symbols.length() < 2) {
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throw new IllegalArgumentException();
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}
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this.random = Objects.requireNonNull(random);
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this.symbols = symbols.toCharArray();
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this.buf = new char[length];
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}
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/**
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* Create an alphanumeric string generator.
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*/
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public RandomString(int length, Random random) {
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this(length, random, alphaNumeric);
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}
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/**
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* Create an alphanumeric strings from a secure generator.
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*/
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public RandomString(int length) {
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this(length, new SecureRandom());
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}
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/**
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* Create session identifiers.
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*/
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public RandomString() {
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this(21);
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}
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/**
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* Generate a random string.
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*/
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public String nextString() {
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for (int idx = 0; idx < buf.length; ++idx) {
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buf[idx] = symbols[random.nextInt(symbols.length)];
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}
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return new String(buf);
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}
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}
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