权重随机算法Java实现

权重随机算法在抽奖，资源调度等系统中应用还是比较广泛的，一个简单的按照权重来随机的实现，权重为几个随机对象(分类)的命中的比例，权重设置越高命中越容易，之和可以不等于100；

简单实现代码如下：

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importjava.util.ArrayList;
importjava.util.List;
importjava.util.Random;  

publicclass WeightRandom {
    staticList<WeightCategory>  categorys = newArrayList<WeightCategory>();
    privatestatic Random random = newRandom();  

    publicstatic void initData() {
        WeightCategory wc1 = newWeightCategory("A",60);
        WeightCategory wc2 = newWeightCategory("B",20);
        WeightCategory wc3 = newWeightCategory("C",20);
        categorys.add(wc1);
        categorys.add(wc2);
        categorys.add(wc3);
    } 

    publicstatic void main(String[] args) {
          initData();
          Integer weightSum = 0;
          for(WeightCategory wc : categorys) {
              weightSum += wc.getWeight();
          } 

          if(weightSum <= 0) {
           System.err.println("Error: weightSum=" + weightSum.toString());
           return;
          }
          Integer n = random.nextInt(weightSum); // n in [0, weightSum)
          Integer m = 0;
          for(WeightCategory wc : categorys) {
               if(m <= n && n < m + wc.getWeight()) {
                 System.out.println("This Random Category is "+wc.getCategory());
                 break;
               }
               m += wc.getWeight();
          } 

    } 

} 

classWeightCategory {
    privateString category;
    privateInteger weight;  

    publicWeightCategory() {
        super();
    } 

    publicWeightCategory(String category, Integer weight) {
        super();
        this.setCategory(category);
        this.setWeight(weight);
    } 

    publicInteger getWeight() {
        returnweight;
    } 

    publicvoid setWeight(Integer weight) {
        this.weight = weight;
    } 

    publicString getCategory() {
        returncategory;
    } 

    publicvoid setCategory(String category) {
        this.category = category;
    }
}