權重隨機算法Java實現

權重隨機算法在抽獎，資源調度等系統中應用還是比較廣泛的，一個簡單的按照權重來隨機的實現，權重為幾個隨機對象(分類)的命中的比例，權重設置越高命中越容易，之和可以不等于100；

簡單實現代碼如下：

    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;  
        }  
    }