java轻量级规则引擎easy-rules使用介绍

   <dependency>
      <groupId>org.jeasy</groupId>
      <artifactId>easy-rules-core</artifactId>
      <version>3.3.0</version>
    </dependency>
    <dependency>
      <groupId>org.jeasy</groupId>
      <artifactId>easy-rules-mvel</artifactId>
      <version>3.3.0</version>
    </dependency>

@Rule(name = "被3整除", description = "number如果被3整除，打印：number is three")
public class ThreeRule {
  /**
   * Condition:条件判断注解：如果return true， 执行Action
   *
   * @param number
   * @return
   */
  @Condition
  public boolean isThree(@Fact("number") int number) {
    return number % 3 == 0;
  }

  /**
   * Action 执行方法注解
   *
   * @param number
   */
  @Action
  public void threeAction(@Fact("number") int number) {
    System.out.println(number + " is three");
  }

  /**
   * Priority:优先级注解：return 数值越小，优先级越高
   *
   * @return
   */
  @Priority
  public int getPriority() {
    return 1;
  }
}

@Rule(name = "被8整除")
public class EightRule {

  /**
   * 条件
   *
   * @param number
   * @return
   */
  @Condition
  public boolean isEight(@Fact("number") int number) {
    return number % 8 == 0;
  }

  /**
   * 满足条件的动作
   *
   * @param number
   */
  @Action
  public void eightAction(@Fact("number") int number) {
    System.out.println(number + " is eight");
  }

  /**
   * 条件判断的优先级
   *
   * @return
   */
  @Priority
  public int getPriority() {
    return 2;
  }
}

@Rule(name = "被3和8同时整除", description = "这是一个组合规则")
public class ThreeEightRuleUnitGroup extends UnitRuleGroup {

  public ThreeEightRuleUnitGroup(Object... rules) {
    for (Object rule : rules) {
      addRule(rule);
    }
  }

  @Override
  public int getPriority() {
    return 0;
  }
}

@Rule(name = "既不被3整除也不被8整除", description = "打印number自己")
public class OtherRule { 
  @Condition
  public boolean isOther(@Fact("number") int number){
    return number % 3 != 0 || number % 8 != 0;
  }

  @Action
  public void printSelf(@Fact("number") int number){
    System.out.print(number);
  }

  @Priority
  public int getPriority(){
    return 3;
  }
}

public class ThreeEightRuleLauncher {

  public static void main(String[] args) {
    /**
     * 创建规则执行引擎
     * 注意: skipOnFirstAppliedRule意思是，只要匹配到第一条规则就跳过后面规则匹配
     */
    RulesEngineParameters parameters = new 
    RulesEngineParameters().skipOnFirstAppliedRule(true);
    RulesEngine rulesEngine = new DefaultRulesEngine(parameters);
    //创建规则
    Rules rules = new Rules();
    rules.register(new EightRule());
    rules.register(new ThreeRule());
    rules.register(new ThreeEightRuleUnitGroup(new EightRule(), new ThreeRule()));
    rules.register(new OtherRule());
    Facts facts = new Facts();
    for (int i=1 ; i<=50 ; i++){
      //规则因素，对应的name，要和规则里面的@Fact 一致
      facts.put("number", i);
      //执行规则
      rulesEngine.fire(rules, facts);
      System.out.println();
    }
  }
}

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Person {
  private String name;

  private boolean adult;

  private int age;
  //getter, setter 省略


  public Person(String name, int age) {
    this.name = name;
    this.age = age;
  }
}

 Rule ageRule = new MVELRule()
        .name("age rule")
        .description("Check if person's age is > 18 and marks the person as adult")
        .priority(1)
        .when("person.age > 18")
        .then("person.setAdult(true);");

name: "alcohol rule" 
description: "children are not allowed to buy alcohol" 
priority: 2 
condition: "person.isAdult() == false" 
actions: 
 - "System.out.println(\"Shop: Sorry, you are not allowed to buy alcohol\");"

public class ShopLauncher {
  public static void main(String[] args) throws Exception {
    //创建一个Person实例(Fact)
    Person tom = new Person("Tom", 19);
    Facts facts = new Facts();
    facts.put("person", tom);

    //创建规则1
    Rule ageRule = new MVELRule()
        .name("age rule")
        .description("Check if person's age is > 18 and marks the person as adult")
        .priority(1)
        .when("person.age > 18")
        .then("person.setAdult(true);");
    //创建规则2
    Rule alcoholRule = new MVELRuleFactory(new YamlRuleDefinitionReader()).
        createRule(new FileReader(ResourceUtils.getFile("classpath:alcohol-rule.yml")));

    Rules rules = new Rules();
    rules.register(ageRule);
    rules.register(alcoholRule);

    //创建规则执行引擎，并执行规则
    RulesEngine rulesEngine = new DefaultRulesEngine();
    System.out.println("Tom: Hi! can I have some Vodka please?");
    rulesEngine.fire(rules, facts);
    System.out.println(JSON.toJSONString(tom));
  }
}