Java权重概率工具类

  简单权重概率工具实现功能：获取int、double类型的随机数，获取概率事件，从集合中取随机元素，获取两数间随机数，获取某数组、list范围内N个随机数，从[0-9] 和 [A-Z] 中随机定长的字符串。

package com.xiu.util;import java.util.ArrayList;import java.util.Collection;import java.util.Collections;import java.util.Iterator;import java.util.LinkedHashMap;import java.util.List;import java.util.Map;import java.util.Map.Entry;import java.util.Random;import java.util.Set;/** *权重概率 * * @author xiu * @version 2017年8月9日 下午3:58:36  */public class Probability {private final static Random random = new Random();private static char[] numbersAndLetters = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ".toCharArray();private Probability() {}/** * 获取随机数 * * @param min * @param max * @return Integer, null: when max < min */public static final Integer rand(int min, int max) {int tmp = max - min;if (tmp < 0) {return null;} else if (tmp == 0) {return min;} else {return random.nextInt(tmp + 1) + min;}}/** * 获取随机数 * * @param min * @param max * @return Integer, null: when max < min */public static final Long rand(long min, long max) {int tmp = Math.abs((int) (max - min));if (tmp < 0) {return null;} else if (tmp == 0) {return min;} else {return random.nextInt(tmp + 1) + min;}}/** * 获取随机数(double) * * @param min *            最小值 * @param max *            最大值 * @param round *            保留多少位小数（不能太大） * @return Double, null: when max < min */public static final Double rand(double min, double max, int round) {double dRound = Math.pow(10, round);int iMin = (int) (min * dRound);int iMax = (int) (max * dRound);Integer r = rand(iMin, iMax);if (r == null) {return null;}return r / dRound;}/** * 获取概率事件，几率最多支持3位小数 * * @param map *            参数举例: Map(1=>20.1, 2=>29.9, 3=>50), 则20.1%几率返回1, 29.9%返回2, *            50%返回3 * @return 返回键值 */public static final <T> T getRand(Map<T, Double> map,int multiple) { // 放大位数// 求和int sum = 0;Iterator<Entry<T, Double>> iter = map.entrySet().iterator();while (iter.hasNext()) {Entry<T, Double> entry = iter.next();Double v = entry.getValue();sum += v * multiple;}if (sum <= 0) {return null;}// 产生0-sum的整数随机int luckNum = random.nextInt(sum) + 1;int tmp = 0;iter = map.entrySet().iterator();while (iter.hasNext()) {Entry<T, Double> entry = iter.next();Double v = entry.getValue();tmp += v * multiple;if (luckNum <= tmp) {return entry.getKey();}}return null;}/** * 获取概率事件，几率最多支持3位小数 * * @param map *            参数举例: HashMap(1=>20.1, 2=>29.9, 3=>50), 则20.1%几率返回1, 29.9%返回2, *            50%返回3 * @return 返回键值 */public static final <T> T getRand(Set<T> map) {int multiple = 1000; // 放大位数// 求和int sum = map.size() * multiple;if (sum <= 0) {return null;}// 产生0-sum的整数随机int luckNum = random.nextInt(sum) + 1;int tmp = 0;for (T one : map) { tmp += multiple;if (luckNum <= tmp) {return one;}}return null;}/** * 从集合中随机一个元素 *  * @date: 2016年4月12日 下午1:18:08 * @param map * @return */public static final <T> T getRand(Collection<T> map) {int multiple = 1000; // 放大位数// 求和int sum = map.size() * multiple;if (sum <= 0) {return null;}// 产生0-sum的整数随机int luckNum = random.nextInt(sum) + 1;int tmp = 0;for (T one : map) {tmp += multiple;if (luckNum <= tmp) {return one;}}return null;}/** * 获取概率事件 * * @param wildsArr *            字符数组 * @param num *            返回结果个数 * @return 选中结果（会有重复的） */public static final int[] getRandByStrArray(int[] wildsArr, int num) {int[] ret = new int[num];int len = wildsArr.length;for (int i = 0; i < num; i++) {int luckNum = random.nextInt(len);System.arraycopy(wildsArr, luckNum, ret, i, 1);}return ret;}/** * 由概率随机是否触发 * * @param chance *            0.00 - 100.00 * @return boolean */public static final boolean isLuck(double chance) {// chance = 50.0;// 测试：30%成功int chanceInt = (int) chance * 100;return Probability.rand(1, 10000) <= chanceInt;}/** * 获取两个数之间的随机数，得出的值符合正态分布 * * @param min *            最小值 * @param max *            最大值 * @param factor *            调整曲线参数 * @return */public static final int gaussianRand(int min, int max, int factor) {if (min > max) {return 0;}int middle = (int) Math.ceil((min + max) / 2.0);int in = max - middle;factor = factor < 0 ? 0 : factor;LinkedHashMap<Integer, Double> map = new LinkedHashMap<Integer, Double>();for (int i = min; i <= max; i++) {if (i == middle) {map.put(i, (double) in);} else {double tmp = Math.abs(in - Math.abs(middle - i));tmp = tmp <= 0 ? 1 : tmp;tmp = factor > 0 ? tmp * (1 + factor / 100.0) : tmp;tmp = tmp > in ? in : tmp;map.put(i, tmp);}}return Probability.getRand(map,1000);}/** * 获取两个数之间的随机数，得出的值符合正态分布 * * @param min *            最小值 * @param max *            最大值 * @return */public static final int gaussianRand(int min, int max) {return gaussianRand(min, max, 0);}/** * 在一个范围内随机一定量的的数值 * * @param start * @param end * @param num * @return */public static List<Integer> randomList(int start, int end, int num){List<Integer> reslut = new ArrayList<>();if (start >= end) {return reslut;}// 返回所有可能，打乱顺序if ((end - start) <= num) {for (int i = start; i < end; i++) {reslut.add(i);}Collections.shuffle(reslut);return reslut;}int temp = 0;for (int i = 0; i < num && i < (end - start); ) {temp = rand(start, end);if (!reslut.contains(temp)) {reslut.add(temp);i++;}}return reslut;}/** * 在一组数据里面随机几个值 * * @param array  随机的源数据 * @param num    获取数据个数 * @return */public static <T> List<T> getRandByArray(T[] array, int num){List<T> reslut = new ArrayList<>();List<T> temp = new ArrayList<>();for (T v : array) {temp.add(v);}if (num >= temp.size()) {return temp;}for (int i = 0; i < num; i++) {int index = rand(0, temp.size() - 1);T value = (T) temp.get(index);if (!reslut.contains(value)) {temp.remove(index);reslut.add(value);}}return reslut;}/** * 从[0-9] 和 [A-Z] 中随机定长的字符串 * * @param length 生成字符串长度 * @return */public static String randomString(int length) {if (length <= 0){return null;}char[] randBuffer = new char[length];for (int i = 0; i < randBuffer.length; i++) {randBuffer[i] = numbersAndLetters[random.nextInt(numbersAndLetters.length - 1)];}return new String(randBuffer);}}