如何維護Drools全球事實計數器並根據其價值應用規則

Question

我是Drools的新手，並且正在研究一個我會得到一批事實（BankAccount信息）的要求。當連續三次輕微賬戶（年齡< 16）插入會話工作記憶中時，我必須發出警報消息。我已經嘗試維護全局變量並在插入小帳戶時增加它。但是我無法定義一個基於全局計數器值的規則，我必須使用它來發送警報消息。請在DRL文件下面找到並提供解決方案。

下面的規則不點火

rule checkCounterAndProduceAlert when 
     b: ResultFact(value > 2) 
    then 
     System.out.println("Alert****"); 
    end 

Here is the DRL full content of DRL file 




     package com.ys.drools.rules 

import com.ys.drools.facts.*; 

rule checkCounterAndProduceAlert 

no-loop true 
when 
    b: ResultFact(value > 2) 
then 
    System.out.println("Alert****"); 
end 


rule checkSeriesOfMinorAccount when 
    a : AccountHolder(age < 16) 
    b : ResultFact() 
then 
b.inc(); 
update(b); 

System.out.println("Incrementing count since minor account appered"); 
System.out.println("***********************************************"); 
System.out.println(b.getValue()); 
end 


rule checMajorAccount when 
    a : AccountHolder(age >16) 
    b :ResultFact() 
then 
b.reset(); 
update(b); 
System.out.println("Making count zero since major account appered"); 
System.out.println(b.getValue()); 
end 

這裏是Java類將加載3個小調賬戶和測試應用程序

package com.ys.drools.data.loader; 

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

import org.kie.api.KieServices; 
import org.kie.api.runtime.KieContainer; 
import org.kie.api.runtime.KieSession; 
import org.slf4j.Logger; 
import org.slf4j.LoggerFactory; 
import com.ys.drools.facts.AccountHolder; 
import com.ys.drools.util.BankAccountUtilService; 
import com.ys.drools.util.DroolsGlobalUtil; 

public class Test { 
    private BankAccountUtilService service; 
    private KieContainer kieContainer; 
    private KieSession kieSession; 
    private static Logger log = LoggerFactory 
      .getLogger(Test.class); 

    private List<AccountHolder> accountHolders=new ArrayList<AccountHolder>(); 

    public Test(){ 
     kieContainer= KieServices.Factory.get().getKieClasspathContainer();  
      kieSession = kieContainer.newKieSession("BankAccountSession"); 
    } 

    public static void main(String[] args) { 
     // TODO Auto-generated method stub 

     Test test=new Test(); 
     List<AccountHolder> aList=test.fillAccountHolderList(); 
     ResultFact fact=new ResultFact(); 
     test.kieSession.insert(fact); 
     for(int i=0;i<aList.size();i++){ 
     test.kieSession.insert(aList.get(i)); 
     test.kieSession.fireAllRules(); 
     } 

     } 


    public List<AccountHolder> fillAccountHolderList(){ 
     List<AccountHolder> accountHolders=new ArrayList<AccountHolder>(); 
     AccountHolder a1=new AccountHolder("Karun", 12); 
     AccountHolder a2=new AccountHolder("kumar", 12); 
     AccountHolder a3=new AccountHolder("rakesh", 10); 
     accountHolders.add(a1); 
     accountHolders.add(a2); 
     accountHolders.add(a3); 
     return accountHolders; 
    } 
} 

請提供此解決方案。運行測試等級時的輸出

Incrementing count since minor account appered 
*********************************************** 
1 
Incrementing count since minor account appered 
*********************************************** 
2 
Incrementing count since minor account appered 
*********************************************** 
3 
Making count zero since major account appered 
0 

（「警告****」）即使在值> 2後也不顯示。規則「checkCounterAndProduceAlert」沒有觸發

Answer 1

解決方案很簡單。

class Counter { 
    private int value; 
    public void inc(){ value++; } 
    public void reset(){ value = 0; } 
    public int getValue(){ return value; } 
} 

插入一個反事實考慮加入$c: Counter()模式的規則後，在適當的工作記憶和使用方法inc和reset。

rule checkCounterAndProduceAlert when 
    Counter(value == 3) 
then 
    System.out.println("Alert****"); 
end 

您可能需要指定是否應在連續未成年人的第六，第九，...個帳戶之後發出另一個警報。

編輯

您也可以申報，並在DRL文件中插入這樣的：

declare Counter 
    value : int 
end 

rule "insert counter" 
    salience 999999 
when 
    not Counter() 
then 
    insert(new Counter()); 
end