随机实例，随机值

/**
 * 随机项
 * @author healy
 *
 * @param <E>
 */
public class RandomEntry<E> {
    /**概率,单位%%(万分之)*/
    private int probability;
    /**概率对应的物品*/
    private E entry;
    
    public RandomEntry(){
        
    }

    /**
     * 
     * @param p 概率单位%%(取值范围：[0-10000))
     * @param entry
     */
    public RandomEntry(int p, E entry) {
        this.probability = p;
        this.entry = entry;
    }
    
    /**
     * 
     * @param p 小数(取值范围：[0-1))
     * @param entry
     */
    public RandomEntry(double p, E entry) {
        this.probability = (int)(p*RandomInstance.maxBaseInt);
        this.entry = entry;
    }

    public int getProbability() {
        return probability;
    }

    public void setProbability(int probability) {
        this.probability = probability;
    }

    public E getEntry() {
        return entry;
    }

    public void setEntry(E entry) {
        this.entry = entry;
    }

    @Override
    public String toString()
    {
        return "RandomEntry [probability=" + probability + ", entry=" + entry + "]";
    }

}

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

/**
 * 随机实例，应用于一个随机事件场景
 * 
 * @author healy
 * 
 */
public class RandomInstance<E>
{
    
    Random r = new Random();
    
    /** 总概率值 */
    int totalProbability = 0;
    
    public final static int maxBaseInt = 10000;
    
    /**
     * 随机项列表
     */
    List<RandomEntry<?>> reList = new ArrayList<RandomEntry<?>>();
    
    ConditionController<?> cc;
    
    public RandomInstance()
    {
        
    }
    
    public RandomInstance(ConditionController<?> cc)
    {
        this.cc = cc;
        
    }
    
    /**
     * 根据随机概率获取对应的实例
     * 
     * @return
     */
    public E getRandomEntry()
    {
        E retObj = null;
        
        int randomValue = r.nextInt(totalProbability);
        
        int curPoint = 0;
        
        int retry = 0;
        
        for (int i = 0; i < reList.size(); i++)
        {
            RandomEntry<?> re = reList.get(i);
//            LogUtil.info("i:" + i + "re:" + re + "curPoint:" + curPoint + "totalProbability:" + totalProbability
//                + "retry:" + retry);
            if (randomValue >= curPoint && randomValue < curPoint + re.getProbability())
            {
                if (cc != null && cc.rejectByCondition(re))
                {
                    // 如果当前概率物品已经达到最大限制，则跳过
                    randomValue = (randomValue + re.getProbability()) % totalProbability;
                    if (++retry >= reList.size())
                    {// 最大跳过次数为列表长度
                        break;
                    }
                }
                else
                {
                    retObj = (E)re.getEntry();
                    if (cc != null)
                    {
                        // 更新条件值
                        cc.updateConditionValue(re);
                    }
                    break;
                }
            }
            else
            {
                curPoint += re.getProbability();
            }
        }
        
        return retObj;
        
    }
    
    public void addRandomEntry(RandomEntry<?>... entries)
    {
        int total = 0;
        if (entries.length > 0)
        {
            
            // 遍历参数内容
            for (RandomEntry<?> re : entries)
            {
                total += re.getProbability();
                reList.add(re);
            }
            totalProbability += total;
        }
    }
    
    public void removeRandomEntry(RandomEntry<?>... entries)
    {
        int total = 0;
        if (entries.length > 0)
        {
            
            // 遍历参数内容
            for (RandomEntry<?> re : entries)
            {
                total += re.getProbability();
                reList.remove(re);
            }
            totalProbability -= total;
        }
    }
    
    @Override
    public String toString()
    {
        return "RandomInstance [r=" + r + ", totalProbability=" + totalProbability + ", reList=" + reList + ", cc="
            + cc + "]";
    }
    
}

RandomInstance<Integer> randomIns = new RandomInstance<Integer>();

for (Mine_reward info : rewardList) {

    RandomEntry<Integer> re = new RandomEntry<Integer>(info.getWeight(), info.getRewardId());

    randomIns.addRandomEntry(re);
}

int rewardId = randomIns.getRandomEntry();