drools入门(二)-规则引擎Drools解决汽水有关问题

drools入门(二)-----规则引擎Drools解决汽水问题

喝汽水问题：
1元钱一瓶汽水，喝完后两个空瓶换一瓶汽水，问：你有50元钱，最多可以喝到几瓶汽水？（不能借空瓶，呵呵无商不奸）

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answer：
1: 如果有超过一元钱， 则买一瓶汽水喝， 此时：?钱减少一元，同时拥有的空瓶增加一个。
2: 如果拥有至少两个空瓶， 则两个空瓶卖给老板兜里的钱加一（或是两个空瓶卖给老板换来一瓶汽水）。

SoftDrink.drl

#created on: 2011-10-18package com.jsptpd.rjy.zyj.maindialect "mvel"#list any import classes here.import com.jsptpd.rjy.zyj.main.SoftDrink.Customer#declare any global variables hererule "和了一瓶汽水"    when        $c:Customer(money>0,$m:money, $e:emptyBottle, $d :drinkBottleSum);    then        $c.money=$m-1;        $c.emptyBottle=$e+1;        $c.drinkBottleSum=$d+1;        System.out.println($c.getName()+"有 "+$c.getMoney()+" 元， 有空瓶 "+$c.getEmptyBottle()+" 个， 喝了 "+$c.getDrinkBottleSum()+" 瓶。");        update($c);endrule "用两个空瓶换了一瓶汽水"    when        $c:Customer(emptyBottle>1,$e:emptyBottle, $d:drinkBottleSum);    then        $c.emptyBottle=$e-2+1;        $c.drinkBottleSum=$d+1;         System.out.println($c.getName()+"有 "+$c.getMoney()+" 元， 有空瓶 "+$c.getEmptyBottle()+" 个， 喝了 "+$c.getDrinkBottleSum()+" 瓶。");        update($c);endrule "结束"    no-loop true    when         $c:Customer(money<=0,emptyBottle<2);    then         System.out.println("计算结束："+$c.getName()+"有 "+$c.getMoney()+" 元， 有空瓶 "+$c.getEmptyBottle()+" 个， 喝了 "+$c.getDrinkBottleSum()+" 瓶。");end

SoftDrink.java

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package com.jsptpd.rjy.zyj.main;import org.drools.KnowledgeBase;import org.drools.KnowledgeBaseFactory;import org.drools.builder.KnowledgeBuilder;import org.drools.builder.KnowledgeBuilderError;import org.drools.builder.KnowledgeBuilderErrors;import org.drools.builder.KnowledgeBuilderFactory;import org.drools.builder.ResourceType;import org.drools.io.ResourceFactory;import org.drools.logger.KnowledgeRuntimeLogger;import org.drools.logger.KnowledgeRuntimeLoggerFactory;import org.drools.runtime.StatefulKnowledgeSession;public class SoftDrink {/** * @param args */public static void main(String[] args) {try {KnowledgeBase knowledgeBase = readKnowledgeBase();StatefulKnowledgeSession statefulKnowledgeSession = knowledgeBase.newStatefulKnowledgeSession();KnowledgeRuntimeLogger knowledgeRuntimeLogger = KnowledgeRuntimeLoggerFactory.newFileLogger(statefulKnowledgeSession, "test");Customer customer=new Customer("小黄", 50, 0, 0);statefulKnowledgeSession.insert(customer);statefulKnowledgeSession.fireAllRules();knowledgeRuntimeLogger.close();statefulKnowledgeSession.dispose();} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}}private static KnowledgeBase readKnowledgeBase() throws Exception {KnowledgeBuilder knowledgeBuilder = KnowledgeBuilderFactory.newKnowledgeBuilder();knowledgeBuilder.add(ResourceFactory.newClassPathResource("SoftDrink.drl"), ResourceType.DRL);KnowledgeBuilderErrors knowledgeBuilderErrors = knowledgeBuilder.getErrors();if (knowledgeBuilderErrors.size() > 0) {for (KnowledgeBuilderError knowledgeBuilderError : knowledgeBuilderErrors) {System.out.println(knowledgeBuilderError);}throw new IllegalArgumentException("KnowledgeBuilder创建失败！");}KnowledgeBase knowledgeBase = KnowledgeBaseFactory.newKnowledgeBase();knowledgeBase.addKnowledgePackages(knowledgeBuilder.getKnowledgePackages());return knowledgeBase;}public static class Customer {private String name = "";private int money = 0;private int emptyBottle = 0;private int drinkBottleSum = 0;public Customer(String name, int money, int emptyBottle,int drinkBottleSum) {super();this.name = name;this.money = money;this.emptyBottle = emptyBottle;this.drinkBottleSum = drinkBottleSum;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getMoney() {return money;}public void setMoney(int money) {this.money = money;}public int getEmptyBottle() {return emptyBottle;}public void setEmptyBottle(int emptyBottle) {this.emptyBottle = emptyBottle;}public int getDrinkBottleSum() {return drinkBottleSum;}public void setDrinkBottleSum(int drinkBottleSum) {this.drinkBottleSum = drinkBottleSum;}}}

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运行结果：

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小黄有 2 元， 有空瓶 2 个， 喝了 94 瓶。

小黄有 2 元， 有空瓶 1 个， 喝了 95 瓶。

小黄有 1 元， 有空瓶 2 个， 喝了 96 瓶。

小黄有 1 元， 有空瓶 1 个， 喝了 97 瓶。

小黄有 0 元， 有空瓶 2 个， 喝了 98 瓶。

小黄有 0 元， 有空瓶 1 个， 喝了 99 瓶。

计算结束：小黄有 0 元， 有空瓶 1 个， 喝了 99 瓶。

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附件直接导入Eclipse中运行.

附件drl文件有java实现，这个是mvel实现。例外还有个重写的。

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