drools入门(二)-----规则引擎Drools解决汽水问题(复杂逻辑)

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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）

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: 2011-10-18
package com.jsptpd.rjy.zyj.main
dialect "mvel"
#list any import classes here.
import com.jsptpd.rjy.zyj.main.SoftDrink.Customer
#declare any global variables here

rule "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);
end

rule "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);
end

rule "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

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 block
e.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;
}
}
}