Drools-Example.md

Drools-Example

Honest Politician

• 使用kmodule的方式调用drools 创建文件：/resources/META-INF/kmodule.xml

  <?xml version="1.0" encoding="UTF-8"?>
  <kmodule xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xmlns="http://www.drools.org/xsd/kmodule">
      <kbase name="HonestPoliticianKB" packages="com.xu.drools.rule.honestpolitician">
          <ksession name="HonestPoliticianKS"/>
      </kbase>
  </kmodule>
  

• rule

  package com.xu.drools                 //package指定命名空间:com.xu.drools
  
  import com.xu.drools.bean.Politician; //import要使用的对象:Politician
  import com.xu.drools.bean.Hope;       //import要使用的对象:Hope
  
  rule "We have an honest Politician"   //rule,定义规则:We have an honest Politician
      salience 10                       //salience，属性部分，定义优先级:10
      when
          exists( Politician( honest == true ) ) //exists,条件部分-LHS，定义当前规则的条件：存在honest==true的Politician
      then
          insertLogical( new Hope() );  //insertLogical,结果部分-RHS，定义规则满足后执行的操作：往当前workingMemory中插入一个新的Hope对象
  end                                   //规则结束
  
  rule "Hope Lives"
      salience 10
      when
          exists( Hope() )
      then
          System.out.println("Hurrah!!! Democracy Lives");
  end
  
  rule "Hope is Dead"
      when
          not( Hope() )                 //not,不存在：不存在Hope对象
      then
          System.out.println( "We are all Doomed!!! Democracy is Dead" );
  end
  
  rule "Corrupt the Honest"
      when
          politician : Politician( honest == true )
          exists( Hope() )
      then
          System.out.println( "I'm an evil corporation and I have corrupted " + politician.getName() );
          modify( politician ) {        //modify,修改：修改politician的Honest为false
              setHonest( false )
          }
  end
  

• 数据的输入

   public static void main(final String[] args) {
      KieContainer kc = KieServices.Factory.get().getKieClasspathContainer();
      System.out.println(kc.verify().getMessages().toString());
      execute( kc );
  }
  
  public static void execute( KieContainer kc ) {
      KieSession ksession = kc.newKieSession("HonestPoliticianKS");
  
      final Politician p1 = new Politician( "President of Umpa Lumpa", true );
      final Politician p2 = new Politician( "Prime Minster of Cheeseland", true );
      final Politician p3 = new Politician( "Tsar of Pringapopaloo", true );
      final Politician p4 = new Politician( "Omnipotence Om", true );
  
      ksession.insert( p1 );
      ksession.insert( p2 );
      ksession.insert( p3 );
      ksession.insert( p4 );
  
      ksession.fireAllRules();
  
      ksession.dispose();
  }
  

• rule的执行顺序

• 执行结果

  Hurrah!!! Democracy Lives
  I'm an evil corporation and I have corrupted President of Umpa Lumpa
  I'm an evil corporation and I have corrupted Prime Minster of Cheeseland
  I'm an evil corporation and I have corrupted Tsar of Pringapopaloo
  I'm an evil corporation and I have corrupted Omnipotence Om
  We are all Doomed!!! Democracy is Dead