Easy Rules规则引擎实战

简介

1、是什么

• 基于java轻量级的规则引擎，学习成本更低、适用性更强
• 本质一个函数，y=f(x1,x2,…,xn)
• Easy Rules 每条规则都有一个条件（condition）和一个动作（action），简单地说，可以将其看作是一组 IF THEN 或类似SQL的when-then语句

2、作用

• 解决业务代码和业务规则分离，实现了将业务决策从应用程序代码中分离。 接受数据输入，解释业务规则，并根据业务规则做出业务决策。

业务系统在应用过程中，常常包含着要处理"复杂、多变"的部分，这部分往往是"业务规则"或者是"数据的处理逻辑"。因此这部分的动态规则的问题，往往需要可配置，并对系统性能和热部署有一定的要求。从开发与业务的视角主要突出以下的一些问题：

• 从开发人员视角来看

1）逻辑复杂，要使用大量if-else来实现，或者使用设计模式。但过于复杂的规则逻辑，使用设计模式也往往是存在大量并且关系复杂的类，导致代码难于维护，对新加入的同学极不友好。

2）变更时需要从头梳理逻辑，在适当的地方进行if…else…代码逻辑调整，耗费大量时间进行梳理。

3）开发周期较长，当需求发生变更时，需要研发人员安排开发周期上线，对于当下快速变化的业务，传统的开发工作方式显得捉襟见肘。

• 从业务人员视角来看

1）业务人员期望友好的管理界面，不需要专业的开发技能就能够完成规则的管理、发布。

2）期望能够实现热部署，由业务人员配置好之后即配即用。

3）减少业务规则对开发人员的依赖。

4）降低需求变动的时间成本，快速验证发布

3、怎么做：

你可以自己构建一个简单的规则引擎。你所需要做的就是创建一组带有条件和动作的规则对象rule，将它们存储在一个集合中rules，然后遍历它们以评估（fire）条件（condition）并执行这些动作（action）。

pom

<dependency><groupId>org.jeasy</groupId><artifactId>easy-rules-core</artifactId><version>3.3.0</version>
</dependency><!--规则定义文件格式，支持json,yaml等-->
<dependency><groupId>org.jeasy</groupId><artifactId>easy-rules-support</artifactId><version>3.3.0</version>
</dependency><!--支持mvel规则语法库-->
<dependency><groupId>org.jeasy</groupId><artifactId>easy-rules-mvel</artifactId><version>3.3.0</version>
</dependency><!-- https://mvnrepository.com/artifact/org.jeasy/easy-rules-spel -->
<dependency><groupId>org.jeasy</groupId><artifactId>easy-rules-spel</artifactId><version>4.1.0</version>
</dependency>

规则

大多数业务规则可以由以下定义表示：

• 名称name：规则命名空间中的唯一规则名称

• 说明description：规则的简要说明

• 优先级priority：相对于其他规则的规则优先级，较小的值表示较高的优先级

• 事实fact：去匹配规则时的一组已知事实

• 条件condition：为了匹配该规则，在给定某些事实的情况下应满足的一组条件

  如果规则条件为true，则规则将被触发执行。否则，规则将被忽略

• 动作action：当条件满足时要执行的一组动作（可以添加/删除/修改事实）

  它可以用于实现各种应用程序逻辑，例如更新数据、发送消息等。

抽象规则Rule

public interface Rule extends Comparable<Rule> {String DEFAULT_NAME = "rule";String DEFAULT_DESCRIPTION = "description";int DEFAULT_PRIORITY = 2147483646;boolean evaluate(Facts var1);void execute(Facts var1) throws Exception;
}

基础规则BasicRule

package org.jeasy.rules.core;import org.jeasy.rules.api.Facts;
import org.jeasy.rules.api.Rule;public class BasicRule implements Rule {protected String name;//名称protected String description;//说明protected int priority;//优先/*** 此方法封装规则的条件（conditions）** @param facts :事实* @return 如果提供的事实适用于该规，则条件返回true*/public boolean evaluate(Facts facts) {return false;}/*** 此方法封装规则的操作（actions）* evaluate方法值为TRUE才能触发execute方法（在满足规则条件时应执行的操作）。* @throws 如果在执行过程中发生错误将抛出Exception*/public void execute(Facts facts) throws Exception {}}

事实类Facts：map

package org.jeasy.rules.api;import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Objects;public class Facts implements Iterable<Map.Entry<String, Object>> {private Map<String, Object> facts = new HashMap();public Object put(String name, Object fact) {Objects.requireNonNull(name);return this.facts.put(name, fact);}public Object remove(String name) {Objects.requireNonNull(name);return this.facts.remove(name);}public <T> T get(String name) {Objects.requireNonNull(name);return this.facts.get(name);}
}

• 扩展：可以将普通对象（包含属性|方法）facts.put()。也可以将rpc对象put进来

@Resource
private MqService mqService;facts.put("mqService", mqService)这样condition方法就可以使用mqService的方法
.when("mqService.doRuleConditions(conditionList,tmpParam)")
或
@Override
public boolean evaluate(@Facts("mqService") MqService mqService) {mqService.doRuleConditions();
}

条件接口

public interface Condition {Condition FALSE = new Condition() {public boolean evaluate(Facts facts) {return false;}};Condition TRUE = new Condition() {public boolean evaluate(Facts facts) {return true;}};boolean evaluate(Facts var1);
}

动作接口

public interface Action {void execute(Facts var1) throws Exception;
}

四种规则定义方式

注解方式

1、eg1（也可以实现Rule接口）

package com.mjp.easyrules.drmo1;import org.jeasy.rules.annotation.Action;
import org.jeasy.rules.annotation.Condition;
import org.jeasy.rules.annotation.Fact;
import org.jeasy.rules.api.Facts;
import org.jeasy.rules.core.BasicRule;public class MyRule extends BasicRule {@Overridepublic boolean evaluate(Facts facts) {return false;}@Overridepublic void execute(Facts facts) throws Exception {}
}

2、纯注解

@Rule(name = "weather rule", description = "if it rains then take an umbrella", priority = 777)
public class WeatherRule {@Conditionpublic boolean itRains(@Fact("rain") boolean rain, @Fact("other") String other) {return rain;}@Action(order = 1)public void takeAnUmbrella() {System.out.println("It rains, take an umbrella!");}@Action(order = 2)public void then2(Facts facts) throws Exception {//my actions2}
}

RuleBuilder 链式

1、eg1

Rule rule = new RuleBuilder().name("myRule").description("myRuleDescription").priority(2).when(facts -> true).then(facts -> {// do Action1}).then(facts -> {// do Action2}).build();

2、eg2

Rule weatherRule = new RuleBuilder().name("weather rule").description("if it rains then take an umbrella").when(facts -> facts.get("rain").equals(true)).then(facts -> System.out.println("It rains, take an umbrella!")).build();

Mvel和Spel表达式

1、eg1：Mvel表达式

Mvel表达式

Rule weatherRule = new MVELRule().name("weather rule").description("if it rains then take an umbrella").when("rain == true").then("System.out.println(\"It rains, take an umbrella!\");");

• when：对象属性

when方法参数，只能是facts对象中key对象，内部定义的属性或方法

.when("person.age > 18")
.when("person.isHappy() == true") 
也可以是类的静态方法
Demo.add(1,2)//这样when会执行去调用类方法add

2、补充：

• when、then内容，可以从自定义的json文件中读取并解析成Mvel表达式形式。解析过程可参考场景6

3、eg2：Spel表达式同理

Spel表达式

Yml配置

eg1: weather-rule.yml

name: "weather rule"
description: "if it rains then take an umbrella"
condition: "true"
actions:- "System.out.println(\"It rains, take an umbrella!\");"

• condition：对象方法

condition: "person.isAdult() == false"
condition: "person.getResult(person.getQualifications())"

eg2：一个yml文件创建多个规则

---
name: adult rule
description: when age is greater than 18, then mark as adult
priority: 1
condition: "person.age > 18"
actions:- "person.setAdult(true);"---
name: weather rule
description: when it rains, then take an umbrella
priority: 2
condition: "rain == true"
actions:- "System.out.println("It rains, take an umbrella!");"

• 读取多条规则

MVELRuleFactory ruleFactory = new MVELRuleFactory(new YamlRuleDefinitionReader());Rule weatherRule = ruleFactory.createRule(new FileReader("D:\\CodeBetter\\src\\main\\resources\\weather-rule.yml"));
// 多条规则
Rules rules = ruleFactory.createRules(new FileReader("rules.yml"));

常用规则类

DefaultRule

package org.jeasy.rules.core;import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.jeasy.rules.api.Action;
import org.jeasy.rules.api.Condition;
import org.jeasy.rules.api.Facts;class DefaultRule extends BasicRule {private Condition condition;//一个规则，一个条件。private List<Action> actions;//一个规则，当满足条件时，可以有多个动作public boolean evaluate(Facts facts) {return this.condition.evaluate(facts);}public void execute(Facts facts) throws Exception {Iterator var2 = this.actions.iterator();while(var2.hasNext()) {Action action = (Action)var2.next();action.execute(facts);}}
}

SpELRule（Spring的表达式注入）

表达式注入

package org.jeasy.rules.spel;import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.jeasy.rules.api.Action;
import org.jeasy.rules.api.Condition;
import org.jeasy.rules.api.Facts;
import org.jeasy.rules.core.BasicRule;
import org.springframework.expression.BeanResolver;
import org.springframework.expression.ParserContext;public class SpELRule extends BasicRule {private Condition condition;//条件private final List<Action> actions;//动作private final ParserContext parserContext;//文本解析private BeanResolver beanResolver;public boolean evaluate(Facts facts) {return this.condition.evaluate(facts);}public void execute(Facts facts) throws Exception {Iterator var2 = this.actions.iterator();while(var2.hasNext()) {Action action = (Action)var2.next();action.execute(facts);}}public SpELRule when(String condition) {this.condition = new SpELCondition(condition, this.parserContext, this.beanResolver);return this;}public SpELRule then(String action) {this.actions.add(new SpELAction(action, this.parserContext, this.beanResolver));return this;}
}

• when方法-SpELCondition

public class SpELCondition implements Condition {private final ExpressionParser parser;private final Expression compiledExpression;private BeanResolver beanResolver;public SpELCondition(String expression, ParserContext parserContext, BeanResolver beanResolver) {this.parser = new SpelExpressionParser();this.beanResolver = beanResolver;this.compiledExpression = this.parser.parseExpression(expression, parserContext);}public boolean evaluate(Facts facts) {StandardEvaluationContext context = new StandardEvaluationContext();context.setRootObject(facts.asMap());context.setVariables(facts.asMap());if (this.beanResolver != null) {context.setBeanResolver(this.beanResolver);}return (Boolean)this.compiledExpression.getValue(context, Boolean.class);}
}

• then方法- SpELAction

public class SpELAction implements Action {private static final Logger LOGGER = LoggerFactory.getLogger(SpELAction.class);private final ExpressionParser parser;private final String expression;private final Expression compiledExpression;private BeanResolver beanResolver;public SpELAction(String expression, ParserContext parserContext, BeanResolver beanResolver) {this.parser = new SpelExpressionParser();this.expression = expression;this.beanResolver = beanResolver;this.compiledExpression = this.parser.parseExpression(expression, parserContext);}public void execute(Facts facts) {try {StandardEvaluationContext context = new StandardEvaluationContext();context.setRootObject(facts.asMap());context.setVariables(facts.asMap());if (this.beanResolver != null) {context.setBeanResolver(this.beanResolver);}this.compiledExpression.getValue(context);} catch (Exception var3) {LOGGER.error("Unable to evaluate expression: '" + this.expression + "' on facts: " + facts, var3);throw var3;}}
}

组合规则

抽象CompositeRule类由一组规则组成。这是一个典型地组合设计模式的实现。可以以不同方式触发组合规则。

三种CompositeRule具体子类：

UnitRuleGroup : 要么应用所有规则，要么不应用任何规则（AND逻辑）
ActivationRuleGroup : 它触发第一个适用规则，并忽略组中的其他规则（XOR逻辑）
ConditionalRuleGroup : 如果具有最高优先级的规则计算结果为true，则触发其余规则

UnitRuleGroup

• 规则1

        Rule weatherRule1 = new MVELRule().name("weather rule1").description("if it rains then move").when("isRain == true").then("System.out.println(\"rule1: It rains, move!\");");

• 规则2

@Rule(name = "weather rule2", description = "if it rains then take an umbrella",priority = 777)
public class WeatherRule {@Conditionpublic boolean itRains(@Fact("isRain") boolean isRain) {return isRain;}@Action(order = 1)public void takeAnUmbrella() {System.out.println("rule2: action1-It rains, take an umbrella!");}@Action(order = 2)public void then(Facts facts) throws Exception {System.out.println("rule2: action2-边打伞，边听歌");}
}

• 执行

// 1.创建事实factFacts facts = new Facts();facts.put("isRain", true);// 2.创建规则1(Mvel形式)Rule weatherRule1 = new MVELRule().name("weather rule1").description("if it rains then move").when("isRain == true").then("System.out.println(\"rule1: It rains, move!\");");// 2.创建规则1(注解形式)WeatherRule weatherRule2 = new WeatherRule();// 3.创建组合规则UnitRuleGroup myUnitRuleGroup = new UnitRuleGroup("myUnitRuleGroup", "unit of weatherRule1 and weatherRule2");myUnitRuleGroup.addRule(weatherRule1);myUnitRuleGroup.addRule(weatherRule2);// 4.创建规则引擎DefaultRulesEngine defaultRulesEngine = new DefaultRulesEngine();// 5.定义RulesRules rules = new Rules();rules.register(myUnitRuleGroup);// 7.执行defaultRulesEngine.fire(rules, facts);

• 输出

rule2: action1-It rains, take an umbrella!
rule2: action2-边打伞，边听歌
rule1: It rains, move!

先输出规则2（优先级为777），规则1（优先级为默认值：2147483646），值越小，优先级越高

规则引擎

引擎接口

public interface RulesEngine {RulesEngineParameters getParameters();List<RuleListener> getRuleListeners();List<RulesEngineListener> getRulesEngineListeners();void fire(Rules var1, Facts var2);Map<Rule, Boolean> check(Rules var1, Facts var2);
}

引擎抽象类

AbstractRuleEngine作用就是抽出多个引擎类共有的，不需要再各自额外重复去实现

引擎类-DefaultRulesEngine

public final class DefaultRulesEngine extends AbstractRuleEngine {private static final Logger LOGGER = LoggerFactory.getLogger(DefaultRulesEngine.class);public void fire(Rules rules, Facts facts) {this.triggerListenersBeforeRules(rules, facts);this.doFire(rules, facts);this.triggerListenersAfterRules(rules, facts);}void doFire(Rules rules, Facts facts) {Iterator var3 = rules.iterator();while(var3.hasNext()) {Rule rule = (Rule)var3.next();String name = rule.getName();int priority = rule.getPriority();if (rule.evaluate(facts)) {this.triggerListenersAfterEvaluate(rule, facts, true);try {this.triggerListenersBeforeExecute(rule, facts);rule.execute(facts);this.triggerListenersOnSuccess(rule, facts);if (this.parameters.isSkipOnFirstAppliedRule()) {LOGGER.debug("Next rules will be skipped since parameter skipOnFirstAppliedRule is set");break;}} catch (Exception var8) {this.triggerListenersOnFailure(rule, var8, facts);if (this.parameters.isSkipOnFirstFailedRule()) {LOGGER.debug("Next rules will be skipped since parameter skipOnFirstFailedRule is set");break;}}} else {this.triggerListenersAfterEvaluate(rule, facts, false);if (this.parameters.isSkipOnFirstNonTriggeredRule()) {LOGGER.debug("Next rules will be skipped since parameter skipOnFirstNonTriggeredRule is set");break;}}}}public Map<Rule, Boolean> check(Rules rules, Facts facts) {this.triggerListenersBeforeRules(rules, facts);Map<Rule, Boolean> result = this.doCheck(rules, facts);this.triggerListenersAfterRules(rules, facts);return result;}private Map<Rule, Boolean> doCheck(Rules rules, Facts facts) {LOGGER.debug("Checking rules");Map<Rule, Boolean> result = new HashMap();Iterator var4 = rules.iterator();while(var4.hasNext()) {Rule rule = (Rule)var4.next();if (this.shouldBeEvaluated(rule, facts)) {result.put(rule, rule.evaluate(facts));}}return result;}
}

规则引擎参数(决定规则之间是否互斥|中断|跳过等)

RulesEngineParameters

skipOnFirstAppliedRule：为true告诉引擎规则，被触发时跳过后面的规则。使用场景是：各个规则之间互斥a || b || c || d，如果a为true，则b、c、d不执行当发现一个满足条件的规则并执行了相关操作后，便不再继续判断其他规则skipOnFirstFailedRule：失败时跳过后面的规则。a && b && c && d，如果a为false，则b、c、d不执行skipOnFirstNonTriggeredRule：一个规则不会被触发跳过后面的规则。如果满足当前的规则，则执行相应的操作，直到遇到不满足条件的规则为止，并且也不会对其他规则进行判断了
rulePriorityThreshold：如果优先级超过定义的阈值，则跳过下一个规则。版本3.3已经不支持更改，默认MaxInt。

实战

场景1- 恒打印

规则description

默认打印Hello World

规则

public class MyRule extends BasicRule {@Overridepublic String getName() {return "my rule";}@Overridepublic String getDescription() {return "my rule description";}@Overridepublic boolean evaluate(Facts facts) {return true;}@Overridepublic void execute(Facts facts) throws Exception {System.out.println("我是一个打印Hello World的规则");}
}

规则引擎：使用DefaultRulesEngine

执行

public static void main(String[] args) {// 1.创建事实factFacts facts = new Facts();// 2.创建条件condition(这里MyRule中默认为true，就不自定义Condition实现类了)// 3.创建动作action(这里MyRule中默认为：打印HelloWorld，就不自定义Action实现类了)// 4.创建规则MyRule myRule = new MyRule();// 5.定义RulesRules rules = new Rules();rules.register(myRule);// 6.创建规则引擎DefaultRulesEngine defaultRulesEngine = new DefaultRulesEngine();// 7.执行defaultRulesEngine.fire(rules, facts);}

输出

DefaultRulesEngineListener - Rules evaluation started
DefaultRuleListener - Rule 'my rule' triggered我是一个打印Hello World的规则DefaultRuleListener - Rule 'my rule' performed successfully

fire方法执行流程

第一步：List<RulesEngineListener> rulesEngineListeners;执行 void beforeEvaluate(Rule var1, Facts var2)第二步：MyRule的boolean evaluate(Facts facts)第三步：List<RuleListener> ruleListeners;执行void afterEvaluate(Rule var1, Facts var2, boolean evaluateResult)第四步：List<RuleListener> ruleListeners;执行void beforeExecute(Rule var1, Facts var2);第五步：MyRule的 void execute(Facts facts)第六步：List<RuleListener> ruleListeners;执行void onSuccess(Rule var1, Facts var2);

场景2-yml

1、规则description

if it rains then take an umbrella

2、定义规则

weather-rule.yml

name: "weather rule"
description: "if it rains then take an umbrella"
condition: "isRain == true"
actions:- "System.out.println(\"It rains, take an umbrella!\");"

3、自定义规则引擎：使用默认的

4、执行

// 1.创建事实factFacts facts = new Facts();facts.put("isRain", true);// 2.创建条件condition(weatherRule中:isRain == true，就不自定义Condition实现类了)// 3.创建动作action(weatherRule中默认为：It rains, take an umbrella!，就不自定义Action实现类了)// 4.创建规则(Yml形式)MVELRuleFactory ruleFactory = new MVELRuleFactory(new YamlRuleDefinitionReader());Rule weatherRule = ruleFactory.createRule(new FileReader("D:\\CodeBetter\\src\\main\\resources\\weather-rule.yml"));// 5.创建规则引擎DefaultRulesEngine defaultRulesEngine = new DefaultRulesEngine();// 6.定义RulesRules rules = new Rules();rules.register(weatherRule);// 7.执行defaultRulesEngine.fire(rules, facts);

场景3 简单if-else

1、功能描述

从1数到100，并且:

• 需求1：如果数字是5的倍数，则打印"i :是5的倍数"
• 需求2：如果数字是7的倍数，请打印"i :是7的倍数"
• 需求3：如果数字是5和7的倍数，请打印"i :是5的倍数、7的倍数"
• 需求4：否则打印数字本身

2、常规实现方法

public class FizzBuzz {public static void main(String[] args) {for(int i = 1; i <= 100; i++) {if (((i % 5) == 0) && ((i % 7) == 0))System.out.print("fizzbuzz");else if ((i % 5) == 0) System.out.print("fizz");else if ((i % 7) == 0) System.out.print("buzz");else System.out.print(i);}}
}

3、使用Easy Rules规则引擎实现

将每个需求编写一条规则:

• rule1

@Rule(name = "Mod5Rule", description = "mod5", priority = 1)
public class Mod5Rule {@Conditionpublic boolean canMod5(@Fact("number") Integer number) {return number % 5 == 0;}@Actionpublic void action(Facts facts) {Integer i = facts.get("number");System.out.print(i + " :是5的倍数");}
}

• rule2

@Rule(name = "Mod7Rule", description = "mod7", priority = 2)
public class Mod7Rule {@Conditionpublic boolean canMod7(@Fact("number") Integer number) {return number % 7 == 0;}@Actionpublic void action(Facts facts) {Integer i = facts.get("number");System.out.print(i + " :是7的倍数");}
}

• rule3

public class Mod5And7Rule extends UnitRuleGroup {public Mod5And7Rule(Object... rules) {for (Object rule : rules) {addRule(rule);}}@Overridepublic int getPriority() {return 0;}
}

• rule4

@Rule(name = "OtherRule", description = "不是5和7的倍数", priority = 3)
public class OtherRule {@Conditionpublic boolean canNotMod5Or7(@Fact("number") Integer number) {return number % 5 != 0 || number % 7 != 0;}@Actionpublic void action(@Fact("number") Integer number) {System.out.print(number);}
}

• 执行

// 创建规则引擎RulesEngineParameters parameters = new RulesEngineParameters().skipOnFirstAppliedRule(true);RulesEngine fizzBuzzEngine = new DefaultRulesEngine(parameters);// 创建规则Rules rules = new Rules();rules.register(new Mod5Rule());rules.register(new Mod7Rule());rules.register(new Mod5And7Rule(new Mod5Rule(), new Mod7Rule()));rules.register(new OtherRule());// 触发规则Facts facts = new Facts();for (int i = 1; i <= 100; i++) {facts.put("number", i);fizzBuzzEngine.fire(rules, facts);}

• 这里规则引擎参数：skipOnFirstAppliedRule(true)：告诉引擎，被触发时跳过后面的规则。

  即当i = 5时，满足规则1（mod5），执行完action1，就不会再去匹配其他rule2、3、4规则了。使用场景是：各个规则之间互斥

场景4-动态规则MVEL表达式+Json字符串

如图1

输入facts：NORMAL_NUMBER和ERROR_NUMBER两个值，使用Mvel表达式解析facts是否满足上述json中定义的condition

• 操作符枚举类(加减乘除，> 、<)

package com.mjp.easyrules.csdn;public enum OperationEnum {GREATER_THAN("GREATER_THAN", "%s > %s", "大于"),GREATER_THAN_EQUAL("GREATER_THAN_EQUAL", "%s >= %s", "大于等于"),LESS_THAN("LESS_THAN", "%s < %s", "小于"),LESS_THAN_EQUAL("LESS_THAN_EQUAL", "%s <= %s", "小于等于"),EQUAL("EQUAL", "%s == %s", "等于"),UNEQUAL("UNEQUAL", "%s != %s", "不等于"),BETWEEN("BETWEEN", "%s >= %s && %s <= %s", "介于之间"),OUT_OF_RANGE("OUT_OF_RANGE", "%s >= %s || %s >= %s", "超出范围"),CONTAINS("CONTAINS", "%s.contains(\"%s\")", "包含"),STARTSWITH("STARTSWITH", "%s.startsWith(\"%s\")", "前缀"),ENDSWITH("ENDSWITH", "%s.endsWith(\"%s\")", "后缀"),;public static OperationEnum getOperationByOperator(String operator) {OperationEnum[] list = OperationEnum.values();for (OperationEnum item : list) {String compareOperator = item.getOperator();if (compareOperator.equals(operator)) {return item;}}return null;}private final String operator;private final String expression;private final String remark;OperationEnum(String operator, String expression, String remark) {this.operator = operator;this.expression = expression;this.remark = remark;}public String getOperator() {return operator;}public String getExpression() {return expression;}public String getRemark() {return remark;}
}

• 逻辑运算符（&&、||、and、or）

public class EasyRulesConstants {// 事实别名public static final String FACT_ALIAS = "fact";// 结果别名public static final String RESULT_ALIAS = "result";// and关系public static final String RELATION_AND = "and";// or关系public static final String RELATION_OR = "or";// 匹配成功信息public static final String MATCH_SUCCESS_MESSAGE = "匹配成功";public static final String FIELD_TYPE = "type";public static final String FIELD_OPERATOR = "operator";public static final String FIELD_NAME = "metricName";public static final String FIELD_VALUE = "value";public static final String FIELD_CHILDREN = "children";public static final String EXPRESSION_TYPE = "EXPRESSION";public static final String RELATION_TYPE = "RELATION";public static final String LEFT_BRACKETS = "(";public static final String RIGHT_BRACKETS = ")";public static final String SYMBOL_SPACE = " ";public static final String SYMBOL_EMPTY = "";public static final String LOGICAL_AND = "&&";public static final String LOGICAL_OR = "||";
}

• 工具类（负责解析自定义json字符串中的condition和action内容，赋值给Mvel规则when、then）

package com.mjp.easyrules.csdn;@Slf4j
public class EasyRulesUtil {/*** 执行规则匹配* @param fact 事实json* @param ruleModel 规则模型*/public static RuleResult match(JSONObject fact, RuleModel ruleModel){// 结果RuleResult result = new RuleResult();result.setRuleId(ruleModel.getRuleId());// 规则实例Facts facts = new Facts();facts.put(FACT_ALIAS, fact);facts.put(RESULT_ALIAS, result);// 规则内容Rule mvelrule = new MVELRule().name(ruleModel.getRuleName()).description(ruleModel.getDescription()).when(ruleModel.getWhenExpression()).then(ruleModel.getThenExpression());// 规则集合Rules rules = new Rules();// 将规则添加到集合rules.register(mvelrule);// 创建规则执行引擎，并执行规则RulesEngine rulesEngine = new DefaultRulesEngine();rulesEngine.fire(rules, facts);return result;}/*** 构建mvel条件表达式* @param json 节点json，例如：* {*     "type": "EXPRESSION",*     "operator": "LESS_THAN",*     "metricName": "NORMAL_NUMBER",*     "value": "11",*     "children": []* }*/public static String buildWhenExpression(JSONObject json) {StringBuilder mvelExpressionSB = new StringBuilder();String type = json.getString(FIELD_TYPE);String operator = json.getString(FIELD_OPERATOR);switch (type) {case EXPRESSION_TYPE:String fieldName = json.getString(FIELD_NAME);String fieldValue = json.getString(FIELD_VALUE);mvelExpressionSB.append(buildOperatorExpress(operator, fieldName, fieldValue));break;case RELATION_TYPE:JSONArray children = json.getJSONArray(FIELD_CHILDREN);if (children.size() == 0) {return SYMBOL_EMPTY;}operator = convertRelationExpress(operator);StringBuilder sb = new StringBuilder();for (int i = 0; i < children.size(); i++) {JSONObject child = children.getJSONObject(i);// 递归构建单个规则条件String childExpression = buildWhenExpression(child);if (!childExpression.isEmpty()) {if (sb.length() > 0) {sb.append(SYMBOL_SPACE).append(operator).append(SYMBOL_SPACE);}sb.append(LEFT_BRACKETS).append(childExpression).append(RIGHT_BRACKETS);}}mvelExpressionSB.append(sb);break;default:break;}return mvelExpressionSB.toString();}/*** 构建mvel表达式* @param operator 操作符* @param fieldName 字段名称* @param value 字段值*/private static String buildOperatorExpress(String operator, String fieldName, Object value) {OperationEnum operationEnum = OperationEnum.getOperationByOperator(operator);if (ObjectUtils.isNotEmpty(operationEnum)) {String expression = operationEnum.getExpression();return String.format(expression, buildValueExpress(fieldName), value);}return SYMBOL_EMPTY;}/*** 构建mvel取值表达式* @param fieldName 字段名称*/private static String buildValueExpress(String fieldName) {return String.format("%s.get(\"%s\")", FACT_ALIAS, fieldName);}/*** 转换条件连接符* @param relation 条件连接符*/private static String convertRelationExpress(String relation) {if (StringUtils.isEmpty(relation)){return SYMBOL_EMPTY;} else if(relation.equalsIgnoreCase(RELATION_AND)){return LOGICAL_AND;} else if(relation.equalsIgnoreCase(RELATION_OR)){return LOGICAL_OR;}return relation;}/*** 构建mvel结果表达式*/public static String buildThenExpression() {StringBuilder sb = new StringBuilder();sb.append(RESULT_ALIAS).append(".setValue(\"").append(MATCH_SUCCESS_MESSAGE).append("\");");log.info("thenExpression: {}", sb);return sb.toString();}@Datapublic static class RuleModel {private String ruleId;String ruleName;String description;String whenExpression;String thenExpression;}@Datapublic static class RuleResult {// 规则主键private String ruleId;// 是否匹配, 默认falseboolean isMatch = false;// 匹配信息，默认为匹配失败String message = "匹配失败";/*** 匹配成功后设置成功信息*/public void setValue(String message){this.message = message;this.isMatch = true;}}
}

• 测试

		// 1. 新增规则EasyRulesUtil.RuleModel ruleModel = new EasyRulesUtil.RuleModel();ruleModel.setRuleId("1");ruleModel.setRuleName("rule1");ruleModel.setDescription("测试规则");// 2. 设置规则条件String ruleJson = "{\n" +"    \"validateCondition\": {\n" +"        \"type\": \"RELATION\",\n" +"        \"operator\": \"OR\",\n" +"        \"children\": [\n" +"            {\n" +"                \"type\": \"EXPRESSION\",\n" +"                \"operator\": \"LESS_THAN\",\n" +"                \"metricName\": \"NORMAL_NUMBER\",\n" +"                \"value\": \"11\",\n" +"                \"children\": []\n" +"            },\n" +"            {\n" +"                \"type\": \"EXPRESSION\",\n" +"                \"operator\": \"LESS_THAN_EQUAL\",\n" +"                \"metricName\": \"ERROR_NUMBER\",\n" +"                \"value\": \"11\",\n" +"                \"children\": []\n" +"            },\n" +"            {\n" +"                \"type\": \"RELATION\",\n" +"                \"children\": [\n" +"                    {\n" +"                        \"type\": \"EXPRESSION\",\n" +"                        \"metricName\": \"NORMAL_NUMBER\",\n" +"                        \"operator\": \"GREATER_THAN\",\n" +"                        \"value\": 10,\n" +"                        \"children\": []\n" +"                    },\n" +"                    {\n" +"                        \"type\": \"EXPRESSION\",\n" +"                        \"metricName\": \"ERROR_NUMBER\",\n" +"                        \"operator\": \"GREATER_THAN\",\n" +"                        \"value\": 100,\n" +"                        \"children\": []\n" +"                    },\n" +"                    {\n" +"                        \"type\": \"RELATION\",\n" +"                        \"children\": [\n" +"                            {\n" +"                                \"type\": \"EXPRESSION\",\n" +"                                \"metricName\": \"NORMAL_NUMBER\",\n" +"                                \"operator\": \"EQUAL\",\n" +"                                \"value\": 1,\n" +"                                \"children\": []\n" +"                            },\n" +"                            {\n" +"                                \"type\": \"EXPRESSION\",\n" +"                                \"metricName\": \"ERROR_NUMBER\",\n" +"                                \"operator\": \"EQUAL\",\n" +"                                \"value\": 1,\n" +"                                \"children \": []\n" +"                            }\n" +"                        ],\n" +"                        \"operator\": \"OR\"\n" +"                    }\n" +"                ],\n" +"                \"operator\": \"OR\"\n" +"            }\n" +"        ]\n" +"    }\n" +"}";JSONObject conditionJson = JSON.parseObject(ruleJson);// 3. 设置factString whenExpression = EasyRulesUtil.buildWhenExpression(conditionJson.getJSONObject("validateCondition"));ruleModel.setWhenExpression(whenExpression);// 4. 设置结果表达式ruleModel.setThenExpression(EasyRulesUtil.buildThenExpression());// 5. 设置匹配条件JSONObject json = new JSONObject();json.put("NORMAL_NUMBER", 12);json.put("ERROR_NUMBER", 12);json.put("省=陕西；市=西安;", 100);// 6. 调用规则匹配EasyRulesUtil.RuleResult result = EasyRulesUtil.match(json, ruleModel);System.out.println(result);

结果分析：显然结果匹配成功。原因如图2

facts：NORMAL_NUMBER = 10、ERROR_NUMBER = 10

condition：如图1

显然NORMAL_NUMBER = 10，满足第一个条件 < 11，直接返回true。

如果我们设置fact：NORMAL_NUMBER = 12，则NORMAL_NUMBER 不满足第一个条件。

但是fact中ERROR_NUMBER = 10 <= 11满足第二个条件，直接返回True

场景5-QLExpress

1、使用阿里的QLExpress

        <dependency><groupId>com.alibaba</groupId><artifactId>QLExpress</artifactId><version>3.3.2</version></dependency>

ExpressRunner runner = new ExpressRunner();DefaultContext<String, MetaRuleResult> context = new DefaultContext<>();context.put("o", MetaRuleResult.builder().skuId(1L).result(true).metaRule("o").failureReason("").build());context.put("l", MetaRuleResult.builder().skuId(1L).result(false).metaRule("l").failureReason("锁库存不可更改").build());context.put("s", MetaRuleResult.builder().skuId(1L).result(true).metaRule("s").failureReason("").build());context.put("w", MetaRuleResult.builder().skuId(1L).result(true).metaRule("w").failureReason("售罄预警").build());context.put("lo", MetaRuleResult.builder().skuId(1L).result(true).metaRule("lo").failureReason("").build());context.put("llo", MetaRuleResult.builder().skuId(1L).result(false).metaRule("llo").failureReason("锁库且修改值小于等于OR值可以更改").build());Object result;DefaultContext<String, Object> computeContext = new DefaultContext<>();for (Map.Entry<String, MetaRuleResult> entry : context.entrySet()) {computeContext.put(entry.getKey(), entry.getValue().getResult());}String ruleExpress = "o&&l&&s&&w&&lo&&llo";result = runner.execute(ruleExpress, computeContext, null, true, false);Boolean bResult = (Boolean) result;System.out.println(bResult);//false

• MetaRuleResult

@Data
@Builder
public class MetaRuleResult {private Long skuId;private Boolean result;private String metaRule;private String failureReason;
}

2、使用EasyRules实现上述功能

• 规则1

@Rule(name = "oRule", description = "修改值>=OR可修改")
public class ORule {@Conditionpublic boolean when(@Fact("oRule") MetaRuleResult oRule) {return oRule.getResult();}@Actionpublic void then(Facts facts) {System.out.println("修改值>=OR可修改");}
}

这里的规则是原子规则

• 规则2

@Rule(name = "lRule", description = "锁库不可更改")
public class LRule {@Conditionpublic boolean when(@Fact("lRule") MetaRuleResult lRule) {return lRule.getResult();}@Actionpublic void then(Facts facts) {System.out.println("没锁库可更改");}
}

• 自定义组合规则

public class MyUnitRuleGroup extends CompositeRule {public MyUnitRuleGroup() {}public MyUnitRuleGroup(String name) {super(name);}public MyUnitRuleGroup(String name, String description) {super(name, description);}public MyUnitRuleGroup(String name, String description, int priority) {super(name, description, priority);}public boolean evaluate(Facts facts) {if (!this.rules.isEmpty()) {Iterator var2 = this.rules.iterator();Rule rule;do {if (!var2.hasNext()) {return true;}rule = (Rule)var2.next();} while(rule.evaluate(facts));// 将失败的facts记录失败的原因String ruleName = rule.getName();MetaRuleResult metaRuleResult = facts.get(ruleName);facts.put("执行失败" + ruleName, metaRuleResult);return false;} else {return false;}}public void execute(Facts facts) throws Exception {Iterator var2 = this.rules.iterator();while(var2.hasNext()) {Rule rule = (Rule)var2.next();rule.execute(facts);}}
}

作用：这里的规则是组合规则，是原子规则的组合形式，可扩展

这里的自定义规则组合，是快速失败机制：即l&&o中如果lRule的condiotion为false，则直接失败，使用facts记录一个失败原因。也可以自定义将每个rule-condition为false的原因都记录下来

• 自定义condition-after-listeren

public class MyRuleListener implements RuleListener {@Overridepublic boolean beforeEvaluate(Rule rule, Facts facts) {return true;}@Overridepublic void afterEvaluate(Rule rule, Facts facts, boolean b) {String ruleName = rule.getName();if (b) {// 只有l&&o为true，才会走到这个逻辑，否则走下面逻辑facts.put(ruleName, MetaRuleResult.builder().skuId(1L).result(true).metaRule(ruleName).failureReason("").build());} else {// l&&o有一个不满足，则总体失败，将各个失败的原因都记录下来StringBuilder sb = new StringBuilder();for (Map.Entry<String, Object> fact : facts) {String key = fact.getKey();if (key.contains("失败")) {MetaRuleResult result = (MetaRuleResult)fact.getValue();// 这里result中有中间参数比如lockStatus，则原因就可以写：lockStatus=true，已锁库，不允许修改sb.append(result.getFailureReason()+ "且");}}facts.put(ruleName, MetaRuleResult.builder().skuId(1L).result(false).metaRule(ruleName).failureReason(sb.toString()).build());}}@Overridepublic void beforeExecute(Rule rule, Facts facts) {}@Overridepublic void onSuccess(Rule rule, Facts facts) {}@Overridepublic void onFailure(Rule rule, Facts facts, Exception e) {}
}

作用：组合规则，执行结果。成功|失败，已经失败原因

• 执行

		// 1.factFacts facts = new Facts();facts.put("oRule",          MetaRuleResult.builder().skuId(1L).result(true).metaRule("o").failureReason("").build());facts.put("lRule",      MetaRuleResult.builder().skuId(1L).result(false).metaRule("l").failureReason("").build());// 2.ruleORule oRule = new ORule();LRule lRule = new LRule();String oAndLRuleName = "o&&l";MyUnitRuleGroup oAndL = new MyUnitRuleGroup(oAndLRuleName, ">=OR且未锁过库规则校验");oAndL.addRule(oRule);oAndL.addRule(lRule);// 3.rulesRules rules = new Rules();rules.register(oAndL);// 4.引擎DefaultRulesEngine engine = new DefaultRulesEngine();engine.registerRuleListener(new MyRuleListener());engine.fire(rules,facts);MetaRuleResult result = facts.get(oAndLRuleName);if (!result.getResult()) {System.out.println(oAndLRuleName + result.getFailureReason());}

• 扩展

1）db获取规则表达式：

先根据网店+品类+角色+修改类型，查询db获取组合规则，比如l&&o

2）工厂模式解析组合规则

然后根据l&&o，解析出规则为l和o，组合成l&&o

3）facts获取数据

自定义策略模式，key为枚举类型，value为对应的rpc查询接口

facts.put("o",          MetaRuleResult.builder().skuId(1L).result(queryData("o")).metaRule("o").failureReason("").build());

这里的queryData方法，根据规则类型o，获取对应的Rpc接口-ORGateway，然后查询or值，然后比较结果

4)组合规则中，判断每个原子规则是否执行通过，失败则记录对应执行失败原因

5)在condition-after中自定义listeren，如果组合规则condition为false，则记录组合规则整体的执行失败以及失败原因

6)如果组合规则整体执行失败，则本次结果为false

场景6- 动态规则Mvel + Json文件

1、背景

动态规则就是由于业务场景的变化，之前的规则已经不适用现在的业务场景，需要更改相对应的规则。

例如：之前是满300减30，现在是满200-30

• 正常情况下我们需要改规则类里面的比较参数代码，然后打包上线。
• 如果使用动态规则，修改一下配置中的规则json文件即可，线上代码会读取最新的规则配置文件，无需上线

2、前提说明

1）规则类中的condtion方法，可以入参传入Facts参数，然后使用facts.get()方法获取内容 ，但是规则文件(eg:json)的condtion中无法传入Facts参数，也就无法使用此参数

2） 自定义RuleListener监听会作用到所有执行的规则，如何仅处理我们指定的规则

@Override
public void afterEvaluate(Rule rule, Facts facts, boolean evaluateResult) {if(evaluateResult && Objects.equals(rule.getName(), "我们指定的规则名称")) {}
}

3、场景

• 输入一个人的信息，信息中包含了这个人的学历等级，作为规则事实

  • 方式一：condition中制定（推荐，可以动态配置0和11）
  • @Condition修饰方法入参( @Fact(“person”) Person person )

  [{"name": "newEducationAdd","description": "修改学历添加列表","condition": "person.getQualifications() >= 0 && person.getQualifications()<=11","priority": 3,"actions": ["System.out.println(\"新规则执行了\")"]}
  ]
  

  • 方式二：将condition条件判断，自定在fact-key中对象的属性和方法中（不推荐）

[{"name": "newEducationAdd","description": "修改学历添加列表","condition": "person.getResult(person.getQualifications())","priority": 3,"actions": ["System.out.println(\"新规则执行了\")"]
}]

@Data
public class Person {// 姓名private String name;// 年龄private int age;// 描述private String dec;// 学历等级private int qualifications;private List<Education> educationList;public boolean getResult(int level){return AddEducation.getResult(level);}
}@UtilityClass
public class AddEducation {public static boolean getResult(int level){return level >= 0 && level <= 11;}
}

• 如果学历等级符合规则，则去查询学历证书情况(集合存储)

• 查出完学历证书后，在检测学历证书与他的学历等级是否匹配，匹配规则为：

  • 学历证书数量与学历等级相同
  • 最大学历证书的学历等级与学历等级一致

• 匹配通过则学历真实，信息中会添加真实学历匹配结果

• 未匹配通过则学历造假嫌疑，信息中会添加造假学历信息

上线

2、前提说明

1）规则类中的condtion方法，可以入参传入Facts参数，然后使用facts.get()方法获取内容 ，但是规则文件(eg:json)的condtion中无法传入Facts参数，也就无法使用此参数

2） 自定义RuleListener监听会作用到所有执行的规则，如何仅处理我们指定的规则

@Override
public void afterEvaluate(Rule rule, Facts facts, boolean evaluateResult) {if(evaluateResult && Objects.equals(rule.getName(), "我们指定的规则名称")) {}
}

3、场景

• 输入一个人的信息，信息中包含了这个人的学历等级，作为规则事实

  • 方式一：condition中制定（推荐，可以动态配置0和11）
  • @Condition修饰方法入参( @Fact(“person”) Person person )

  [{"name": "newEducationAdd","description": "修改学历添加列表","condition": "person.getQualifications() >= 0 && person.getQualifications()<=11","priority": 3,"actions": ["System.out.println(\"新规则执行了\")"]}
  ]
  

  • 方式二：将condition条件判断，自定在fact-key中对象的属性和方法中（不推荐）

[{"name": "newEducationAdd","description": "修改学历添加列表","condition": "person.getResult(person.getQualifications())","priority": 3,"actions": ["System.out.println(\"新规则执行了\")"]
}]

@Data
public class Person {// 姓名private String name;// 年龄private int age;// 描述private String dec;// 学历等级private int qualifications;private List<Education> educationList;public boolean getResult(int level){return AddEducation.getResult(level);}
}@UtilityClass
public class AddEducation {public static boolean getResult(int level){return level >= 0 && level <= 11;}
}

• 如果学历等级符合规则，则去查询学历证书情况(集合存储)

• 查出完学历证书后，在检测学历证书与他的学历等级是否匹配，匹配规则为：

  • 学历证书数量与学历等级相同
  • 最大学历证书的学历等级与学历等级一致

• 匹配通过则学历真实，信息中会添加真实学历匹配结果

• 未匹配通过则学历造假嫌疑，信息中会添加造假学历信息

场景7-履约缺货处罚金额计算