[Drools Demos] 其 (二) : 数据传递

悠悠 2022-03-17 07:50 194阅读 0赞

### 前言 ###

本章主要对应项目内的`drools-demos`内的HelloWorld样例.主要讲解Drools内是如何进行数据传递的.

基础配置: JDK 1.7 + Eclipse Mar + Maven  
依赖: Drools插件(非必须)

本章主要对应项目内的`drools-quickstart`子模块.  
Github地址: [https://github.com/SeanYanxml/drools-train][https_github.com_SeanYanxml_drools-train]

--------------------

### 详细内容 ###

通过上节我们可以看到,通过`kSession.insert(message);`方法,将message对象传递给了DRL规则文件内部.

*  Q1:  
    那么,有一个问题,DRL内改变对象后,规则文件外的对象`message`是否改变了?我们带着这个问题进行今天的测试

> Message.java(POJO类)

package com.yanxml.drools.demos.pojo;
    
    public class Message {
    	// status 4 种状态
    	public static final int STATUS_1 = 1;
    	public static final int STATUS_2 = 2;
    	public static final int STATUS_3 = 3;
    	public static final int STATUS_4 = 4;
    	
    	private String message;
    	private int status;
    	
    	public String getMessage() {
    		return message;
    	}
    	public void setMessage(String message) {
    		this.message = message;
    	}
    	public int getStatus() {
    		return status;
    	}
    	public void setStatus(int status) {
    		this.status = status;
    	}
    
    }

> kmodule.xml(kmodule配置文件)

<?xml version="1.0" encoding="utf-8" ?>
    <kmodule xmlns="http://jboss.org/kie/6.0.0/kmodule">
    	
    	<kbase name="kbase-helloworld" packages="com.yanxml.drools.demos.helloworld">
    		<ksession name="ksession-helloworld"/>
    	</kbase>
    	
    </kmodule>

> Helloworld.drl

import com.yanxml.drools.demos.pojo.Message;
    
    no-loop true
    
    rule "TransmitHelloworldRule"
    	when 
    		$m : Message( status == Message.STATUS_1, myMessage:message)
    	then
    		System.out.println("Hit Transmit HelloWorld Rule.");
    		$m.setMessage("STATUS_2");
    		$m.setStatus(Message.STATUS_2);
    //		update(m);
    end

> DroolsBaseTest.java(基础测试类)

package com.yanxml.drools.demos.test;
    
    import org.junit.Before;
    import org.kie.api.KieServices;
    import org.kie.api.runtime.KieContainer;
    
    public abstract class DroolsBaseTest {
    	
    	protected KieServices kieServices;
    	protected KieContainer kieContainer;
    	
    	@Before
    	public void init(){
    		kieServices =  KieServices.Factory.get();
    		kieContainer = kieServices.getKieClasspathContainer(); 
    	}
    
    }

> HelloWorldTest.java(HelloWorld测试类)

package com.yanxml.drools.demos.test;
    
    import org.drools.core.base.RuleNameStartsWithAgendaFilter;
    import org.junit.Test;
    import org.kie.api.runtime.KieSession;
    
    import com.yanxml.drools.demos.pojo.Message;
    import com.yanxml.drools.demos.service.HelloWolrdMessageService;
    
    public class HelloWorldTest extends DroolsBaseTest {
    	
    //	@Test
    	public void testHelloWorld(){
    		KieSession kieSession = kieContainer.newKieSession("ksession-helloworld");
    		Message message = new Message();
    		message.setMessage("STATUS_1");
    		message.setStatus(Message.STATUS_1);
    		
    		System.out.println("Rule Before - Message: "+message.getMessage()+" status:"+message.getStatus());
    		
    		// hit rule
    		kieSession.insert(message);
    		kieSession.fireAllRules();
    		
    		// 同步等待 - 等待rule执行完毕后 后面的语句才被执行。
    		System.out.println("Rule After - Message: "+message.getMessage()+" status:"+message.getStatus());
    	}
    	
    }

> 测试结果:

Rule Before - Message: STATUS_1 status:1
    Hit Transmit HelloWorld Rule.
    Rule After - Message: STATUS_2 status:2

结论: 规则内和规则外使用的是同一个对象.规则内对象改变了,规则外也会跟随改变.

*  Q2:  
    我们在规则内部调用规则外的工具类等,应当进行如何调用呢?

> HelloWorldService(待回调的Service方法)

package com.yanxml.drools.demos.service;
    
    import com.yanxml.drools.demos.pojo.Message;
    
    public class HelloWolrdMessageService {
    	
    	// 更改业务
    	public void changeMessageState(Message message,String msg, int status){
    		message.setMessage(msg);
    		message.setStatus(status);
    	}
    	
    	public void insertMessage(Message message){
    		// 插入message业务(暂略)
    		// messageDao.insert();
    	}
    
    }

> Helloworld.drl(规则补充)

rule "InvokeHelloWorldRule"
    	when
    		$m : Message()
    		$msg : String()
    		$status : Integer()
    		$helloWolrdMessageService : HelloWolrdMessageService()
    	then
    		System.out.println("Hit Invoke HelloWorld Rule.");
    		$helloWolrdMessageService.changeMessageState($m,$msg,$status);
    end

> HelloWorldTest(测试类补充)

@Test
    	public void testHelloWorldInvoke(){
    		KieSession kieSession = kieContainer.newKieSession("ksession-helloworld");
    		Message message = new Message();
    		message.setMessage("STATUS_1");
    		message.setStatus(Message.STATUS_1);
    		
    		HelloWolrdMessageService helloWolrdMessageService = new HelloWolrdMessageService();
    		
    		
    		System.out.println("Rule Before - Message: "+message.getMessage()+" status:"+message.getStatus());
    		
    		// hit rule
    		kieSession.insert(message);
    		
    		kieSession.insert("STATUS_3");
    		kieSession.insert(Message.STATUS_3);
    		kieSession.insert(helloWolrdMessageService);
    		
    //		kieSession.fireAllRules();
    
    		kieSession.fireAllRules(new RuleNameStartsWithAgendaFilter("Invoke"));
    		
    		// 同步等待 - 等待rule执行完毕后 后面的语句才被执行。
    		System.out.println("Rule After - Message: "+message.getMessage()+" status:"+message.getStatus());
    	}

> 测试结果:

Rule Before - Message: STATUS_1 status:1
    Hit Invoke HelloWorld Rule.
    Rule After - Message: STATUS_3 status:3

结论: 通过`kieSession.insert(service)`方法一并传入即可.

[https_github.com_SeanYanxml_drools-train]: https://github.com/SeanYanxml/drools-train