Java Drools - 应用哪些规则和事实列表

Question

我对 drools 有点陌生，我想对一个项目了解更多，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;
    }
}

ma​​in.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

这可能吗？我检查了WorkingMemory、Endpoint、FactHandle 类，但什么也没检查。

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)。

有关更多详细信息，请参阅此帖子:Drools- how to find out which all rules were matched?

希望对你有帮助