Java Drools - 应用了哪些规则和事实列表

Question

我对 drools 有点陌生，我想为一个项目了解更多，所以我在 eclipse 上用 drools 做了一个简单的程序。工作流程非常简单，我有一个珠宝产品模型，对于每件珠宝，我都会根据名称应用一个折扣。

效果很好，但我想查看事实列表以及每个触发规则使用了哪些事实。我有这个：

Rules.drl

package com.rule

import com.javainuse.model.Product
import com.javainuse.model.Counter

rule "Offer for Diamond"
    when 
        productObject: Product(type=="diamond")
    then
        productObject.setDiscount(15);
    end

rule "Offer for Gold"
    when 
        productObject: Product(type=="gold")
    then
        productObject.setDiscount(25);
    end

model.Product.java

package com.javainuse.model;

public class Product {
    private String type;
    private int discount;

   public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public int getDiscount() {
        return discount;
    }

    public void setDiscount(int discount) {
        this.discount = discount;
    }
}

main.DroolsTest.java

package com.javainuse.main;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.util.Collection;
import java.util.Iterator;
import org.drools.compiler.compiler.DroolsParserException;
import org.drools.compiler.compiler.PackageBuilder;
import org.drools.core.FactHandle;
import org.drools.core.RuleBase;
import org.drools.core.RuleBaseFactory;
import org.drools.core.WorkingMemory;
import com.javainuse.model.Product;

public class DroolsTest {

    public static void main(String[] args) throws DroolsParserException,
            IOException {
        DroolsTest droolsTest = new DroolsTest();
        droolsTest.executeDrools();
    }

    public void executeDrools() throws DroolsParserException, IOException {

        PackageBuilder packageBuilder = new PackageBuilder();

        String ruleFile = "/com/rule/Rules.drl";
        InputStream resourceAsStream = getClass().getResourceAsStream(ruleFile);

        Reader reader = new InputStreamReader(resourceAsStream);
        packageBuilder.addPackageFromDrl(reader);
        org.drools.core.rule.Package rulesPackage = packageBuilder.getPackage();
        RuleBase ruleBase = RuleBaseFactory.newRuleBase();
        ruleBase.addPackage(rulesPackage);

        WorkingMemory workingMemory = ruleBase.newStatefulSession();

        Product product = new Product();
        Product product2 = new Product();
        product.setType("gold");
        product2.setType("diamond");

        //List of facts!
        workingMemory.insert(product);
        workingMemory.insert(product2);
        workingMemory.fireAllRules();

System.out.println("Discount for " + product.getType() + " is " + product.getDiscount());

        System.out.println("Discount for " + product2.getType() + " is " + product2.getDiscount());

        //how many facts
        System.out.println("There are " + workingMemory.getFactCount() + " facts");
        //facts handles
        Collection<org.kie.api.runtime.rule.FactHandle> x = workingMemory.getFactHandles();
        System.out.println("Facts Handles: " + x +"\n");

        FactHandle fh;
        Iterator<org.kie.api.runtime.rule.FactHandle> it =  x.iterator();
        while(it.hasNext())
        {
            fh = (FactHandle) it.next();
            System.out.println("FactHandle to string "+fh.toExternalForm().toString());
        }
    }
}

输出：

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
Discount for gold is 25
Discount for diamond is 15
There are 2 facts
Facts Handles: [[fact 0:2:1889057031:1889057031:2:DEFAULT:NON_TRAIT:com.javainuse.model.Product@7098b907], [fact 0:1:93199773:93199773:1:DEFAULT:NON_TRAIT:com.javainuse.model.Product@58e1d9d]]

FactHandle to string 0:2:1889057031:1889057031:2:DEFAULT:NON_TRAIT
FactHandle to string 0:1:93199773:93199773:1:DEFAULT:NON_TRAIT

I want something like this:

Discount for gold is 25
Discount for diamond is 15
There are 2 facts: gold, diamond
gold triggered rule Offer for Gold
diamond triggered Offer for Diamond

可能吗？我检查了 WorkingMemory、Endpoint、FactHandle 的类，但什么也没有。

Answer 1

您可以使用 AgendaEventListener 在规则匹配时收到通知（以及使其匹配的事实）。

有关详细信息，请参阅此 post：Drools- how to find out which all rules were matched?

希望对您有所帮助，

Answer 2

我找到了一个解决方案，只是为了检查规则命中时在事实列表中触发了哪些事实。

在 model.Product.java 上创建了一个函数 return getType();

然后在主程序上main.Droolstest.java：调用函数获取事实getfacts(workingMemory);

public void getfacts( WorkingMemory workingMemory )
{
FactHandle fh;
Collection<org.kie.api.runtime.rule.FactHandle> x = workingMemory.getFactHandles();
Iterator<org.kie.api.runtime.rule.FactHandle> it =  x.iterator();

System.out.println("List of facts");
while(it.hasNext())
{
    fh = (FactHandle) it.next();

    Object getobj = workingMemory.getObject(fh);
    //System.out.println("GetObject to string: " + ((Object)getobj));

    if (getobj instanceof RuleFact) {
        System.out.println("\nIt's a Fact: ");
        ((RuleFact) getobj).print();
    }
    //System.out.println("FactHandle to string "+ ((Object) fh.toExternalForm()).toString());
   }

}

output:

Constructor RuleFact to gold
Constructor RuleFact to diamond
Constructor RuleFact to wood
Inserting facts on the facts list
List of facts

It's a Fact: 
gold

It's a Fact: 
diamond

Fire all the rules
Discount for gold is 95
Discount for diamond is 15
Discount for wood is 0
There are 2 facts
Inserting fact on the facts list
New Rule - fire all the rules
There are 3 facts
Discount for gold is 95
Discount for diamond is 15
Discount for wood is 90
List of facts

It's a Fact: 
wood

It's a Fact: 
gold

It's a Fact: 
diamond

Answer 3

使用 Drools 插件在 Eclipse 中调试 drools 规则有多种选择（因为你告诉过你正在使用这个 IDE）。

考虑使用KieRuntimeLogger获取调试信息。

获得KieSession实例后可以注册一个新的KieRuntimeLogger:

KieSession kSession = kContainer.newKieSession("ksession-rules");

KieRuntimeLogger kieLogger = ks.getLoggers().newFileLogger(kSession, "log");

运行您的 drools 应用程序并检查您的项目文件夹。在那里您会找到 log.log（原文如此！）文件，其中包含规则执行期间调用的操作列表。

这里是详细的article。

Java Drools - 应用了哪些规则和事实列表

Java Drools - which Rules are applied and facts list

java

drools