java语言实现权重随机算法完整实例

package com.nggirl.test.weight.random;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Random;public class WeightRandom {public static void main(String[] args){WeightRandom wr = new WeightRandom();wr.initWeight(new String[]{"1","2","3","4"}, new Integer[]{100,100,200,600});Random r = new Random();for (int i = 0; i < 10; i++){Integer rv = r.nextint(wr.getMaxRandomValue());System.out.println(rv);System.out.println(wr.getElementByRandomValue(rv).getKey() + " " + rv);}HashMap<String, Integer> keyCount = new HashMap<String, Integer>();keyCount.put("1", 0);keyCount.put("2", 0);keyCount.put("3", 0);keyCount.put("4", 0);for (int i = 0; i < 10000; i++){Integer rv = r.nextint(wr.getMaxRandomValue());String key = wr.getElementByRandomValue(rv).getKey();keyCount.put(key, keyCount.get(key).intValue()+1);}System.out.println("");}private List<WeightElement> weightElements;public void initWeight(String[] keys, Integer[] weights){if(keys == null || weights == null || keys.length != weights.length){return;}weightElements = new ArrayList<WeightElement>();for (int i=0; i< keys.length; i++){weightElements.add(new WeightElement(keys[i], weights[i]));}rangeWeightElemnts();printRvs();}private void rangeWeightElemnts(){if(weightElements.size() == 0){return;}WeightElement ele0 = weightElements.get(0);ele0.setThresholdLow(0);ele0.setThresholdHigh(ele0.getWeight());for (int i = 1; i < weightElements.size(); i++){WeightElement curElement = weightElements.get(i);WeightElement preElement = weightElements.get(i - 1);curElement.setThresholdLow(preElement.getThresholdHigh());curElement.setThresholdHigh(curElement.getThresholdLow() + curElement.getWeight());}}public WeightElement getElementByRandomValue(Integer rv){//因为元素权重范围有序递增，所以这里可以改为二分查找for (WeightElement e:weightElements){if(rv >= e.getThresholdLow() && rv < e.getThresholdHigh()){return e;}}return null;}public Integer getMaxRandomValue(){if(weightElements == null || weightElements.size() == 0){return null;}return weightElements.get(weightElements.size() - 1).getThresholdHigh();}public void printRvs(){for (WeightElement e:weightElements){System.out.println(e.toString());}}static class WeightElement{private String key;private Integer weight;private Integer thresholdLow;private Integer thresholdHigh;public WeightElement(){}public WeightElement(Integer weight){this.key = weight.toString();this.weight = weight;}public WeightElement(String key, Integer weight){this.key = key;this.weight = weight;}public String getKey() {return key;}public void setKey(String key) {this.key = key;}public Integer getWeight() {return weight;}public void setWeight(Integer weight) {this.weight = weight;}public Integer getThresholdLow() {return thresholdLow;}public void setThresholdLow(Integer thresholdLow) {this.thresholdLow = thresholdLow;}public Integer getThresholdHigh() {return thresholdHigh;}public void setThresholdHigh(Integer thresholdHigh) {this.thresholdHigh = thresholdHigh;}public String toString(){return "key:"+this.key + " weight:" + this.weight + " low:"+this.thresholdLow+" heigh:"+this.thresholdHigh;}}}