权重随机算法Java实现详解编程语言

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：

    import java.util.ArrayList;   
    import java.util.List;   
    import java.util.Random;   
       
    public class WeightRandom {   
        static List<WeightCategory>  categorys = new ArrayList<WeightCategory>();   
        private static Random random = new Random();   
           
        public static void initData() {   
            WeightCategory wc1 = new WeightCategory("A",60);   
            WeightCategory wc2 = new WeightCategory("B",20);   
            WeightCategory wc3 = new WeightCategory("C",20);   
            categorys.add(wc1);   
            categorys.add(wc2);   
            categorys.add(wc3);   
        }   
       
        public static 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();   
              }   
       
                 
        }   
       
    }   
       
    class WeightCategory {   
        private String category;   
        private Integer weight;   
           
       
        public WeightCategory() {   
            super();   
        }   
       
        public WeightCategory(String category, Integer weight) {   
            super();   
            this.setCategory(category);   
            this.setWeight(weight);   
        }   
       
       
        public Integer getWeight() {   
            return weight;   
        }   
       
        public void setWeight(Integer weight) {   
            this.weight = weight;   
        }   
       
        public String getCategory() {   
            return category;   
        }   
       
        public void setCategory(String category) {   
            this.category = category;   
        }   
    }