规则引擎 - Easy Rules

Easy Rules

- - 依赖
  - demo
  - - demo1
    - demo2
  - 总结

Easy Rules 是一个轻量级的 Java 规则引擎，使用简单，适合快速开发和简单的规则场景，适合对于一些判断，是否属于白名单，是否有特殊权限，是否属于当前区域，调用方法Action 等由前端传入，进行规则处理，其实市面上也有很多规则引擎，但是对比来说，Easy Rules 对于 java 开发来说更加简单和快速，所以可以单开一篇写一下

依赖

xml 复制代码

<dependency>
    <groupId>org.jeasy</groupId>
    <artifactId>easy-rules-core</artifactId>
    <version>4.4.0</version>
</dependency>

demo

demo1

java 复制代码

import org.jeasy.rules.api.Facts;
import org.jeasy.rules.api.Rules;
import org.jeasy.rules.api.RulesEngine;
import org.jeasy.rules.core.DefaultRulesEngine;
import org.jeasy.rules.core.RuleBuilder;
/**
 * FileName: FactsExample.java
 * Author:   寿春
 * Date:     2025/4/21 19:54
 * <p>
 */
class Person {
    private String name;
    private int age;

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

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }
}


public class FactsExample {
    public static void main(String[] args) {
        // 创建 Person 对象
        Person person = new Person("John", 20);

        // 使用流式 API 定义规则
        var ageRule = RuleBuilder
               .begin()
               .name("Age Rule")
               .description("Check if the person's age is greater than 18")
               .when(facts -> ((Person) facts.get("person")).getAge() > 18)
               .then(facts -> System.out.println(((Person) facts.get("person")).getName() + " is an adult."))
               .build();

        // 创建规则集合
        Rules rules = new Rules();
        rules.register(ageRule);

        // 创建事实集合
        Facts facts = new Facts();
        // 向事实集合中添加数据
        facts.put("person", person);

        // 创建规则引擎
        RulesEngine rulesEngine = new DefaultRulesEngine();

        // 执行规则，将规则集合和事实集合传递给规则引擎
        rulesEngine.fire(rules, facts);
    }
}

demo2

java 复制代码

import org.jeasy.rules.annotation.Action;
import org.jeasy.rules.annotation.Condition;
import org.jeasy.rules.annotation.Rule;

@Rule(name = "Age Rule", description = "Check if the person's age is greater than 18")
public class AgeRule {

    private Person person;

    public AgeRule(Person person) {
        this.person = person;
    }

    @Condition
    public boolean isAdult() {
        return person.getAge() > 18;
    }

    @Action
    public void printMessage() {
        System.out.println(person.getName() + " is an adult.");
    }
}

java 复制代码

/**
 * FileName: FactsExample.java
 * Author:   寿春
 * Date:     2025/4/21 20:01
 * <p>
 */
@Data
@AllArgsConstructor
public class Person {
    private String name;
    private int age;



    public static void main(String[] args) {
        // 创建 Person 对象
        Person person = new Person("John", 20);

        // 创建规则
        AgeRule ageRule = new AgeRule(person);

        // 创建规则集合
        Rules rules = new Rules();
        rules.register(ageRule);

        // 创建事实集合
        Facts facts = new Facts();
        facts.put("person", person);

        // 创建规则引擎
        RulesEngine rulesEngine = new DefaultRulesEngine();

        // 执行规则
        rulesEngine.fire(rules, facts);
    }
}

总结

逻辑很简单

创建一个规则， Rules rules = new Rules();
需要什么规则 RuleBuilder
创建一个事实 Facts facts = new Facts();
创建规则引擎 RulesEngine rulesEngine = new DefaultRulesEngine();
执行规则 rulesEngine.fire(rules, facts); 这个规则这个事实