java 规则引擎实例_Java规则引擎——EasyRules的使用实例
一、easy-rule使用的几种方式：
1、直接在代码中写规则
packageorg.songdan.easy.rules.anno;importorg.jeasy.rules.api.Facts;importorg.jeasy.rules.api.Rules;importorg.jeasy.rules.api.RulesEngine;importorg.jeasy.rules.core.DefaultRulesEngine;importorg.jeasy.rules.core.RulesEngineParameters;/***@authorcoco_xu
* @date 2020-04-16*/
public classFizzBuzzMainWithRule {public static voidmain(String[] args) {//create a rules engine
RulesEngineParameters parameters = new RulesEngineParameters().skipOnFirstAppliedRule(true);
RulesEngine fizzBuzzEngine= newDefaultRulesEngine(parameters);//create rules
Rules rules = newRules();
rules.register(newRuleClass.FizzRule());
rules.register(newRuleClass.BuzzRule());
rules.register(new RuleClass.FizzBuzzRule(new RuleClass.FizzRule(), newRuleClass.BuzzRule()));
rules.register(newRuleClass.NonFizzBuzzRule());//fire rules
Facts facts = newFacts();for (int i = 1; i <= 100; i++) {
facts.put("number", i);
fizzBuzzEngine.fire(rules, facts);
System.out.println();
}
}
}
2、
packageorg.songdan.easy.rules.fluent;import org.jeasy.rules.api.*;importorg.jeasy.rules.core.DefaultRulesEngine;importorg.jeasy.rules.core.InferenceRulesEngine;importorg.jeasy.rules.core.RuleBuilder;importorg.jeasy.rules.core.RulesEngineParameters;importorg.jeasy.rules.mvel.MVELRule;importorg.jeasy.rules.support.UnitRuleGroup;importorg.songdan.easy.rules.model.NumObj;/***@author: coco_xu
* @create: 2020-04-16
**/
public classFizzBuzzMainWIthFluent {public static voidmain(String[] args) {
Rule fizzRule= new RuleBuilder().name("fizzRule").description("fizz num").when(newCondition() {public booleanevaluate(Facts facts) {
Integer num= facts.get("num");return num % 5 == 0;
}
}).then(newAction() {public void execute(Facts facts) throwsException {
System.out.println(facts.get("num")+" is a fizz num!!!");
}
}).priority(1).build();
Rule buzzRule= new RuleBuilder().name("fizzRule").description("fizz num").when(newCondition() {public booleanevaluate(Facts facts) {
Integer num= facts.get("num");return num % 7 == 0;
}
}).then(newAction() {public void execute(Facts facts) throwsException {
System.out.println(facts.get("num")+" is a buzz num!!!");
}
}).priority(2).build();
UnitRuleGroup unitRuleGroup= new UnitRuleGroup("mixRule","fizz and buzz num ",3);
unitRuleGroup.addRule(fizzRule);
unitRuleGroup.addRule(buzzRule);
MVELRule mvelRule= newMVELRule()
.name("weather rule")
.description("if it rains then take an umbrella")
.when("obj.generate() == 10")
.then("System.out.println(\"It rains, take an umbrella!\");");
RulesEngineParameters parameters= new RulesEngineParameters().skipOnFirstAppliedRule(false);
RulesEngine fizzBuzzEngine= newDefaultRulesEngine(parameters);
Facts facts= newFacts();
Rules rules= newRules();
rules.register(fizzRule);
rules.register(buzzRule);
rules.register(unitRuleGroup);
rules.register(mvelRule);for (int i = 0; i < 100; i++) {
facts.put("num",i);
fizzBuzzEngine.fire(rules,facts);
System.out.println();
}
facts.put("obj", new NumObj(10));
fizzBuzzEngine.fire(rules,facts);
}
}
3、在yml文件中配置规则，然后进行读取
packageorg.songdan.easy.rules.yml;importorg.jeasy.rules.api.Facts;importorg.jeasy.rules.api.Rules;importorg.jeasy.rules.api.RulesEngine;importorg.jeasy.rules.core.DefaultRulesEngine;importorg.jeasy.rules.core.RulesEngineParameters;importorg.jeasy.rules.mvel.MVELRuleFactory;importorg.songdan.easy.rules.anno.DiseaseModel;importjava.io.FileNotFoundException;importjava.io.InputStreamReader;/***@author: coco_xu
* @create: 2020-04-16
**/
public classFizzBuzzMainWithYmlRule {private staticString result ;public static void main(String[] args) throwsFileNotFoundException {//create a rules engine
RulesEngineParameters parameters = new RulesEngineParameters().skipOnFirstAppliedRule(true);
RulesEngine fizzBuzzEngine= newDefaultRulesEngine(parameters);
InputStreamReader inputStreamReader= new InputStreamReader(FizzBuzzMainWithYmlRule.class.getClassLoader().getResourceAsStream("rules_string.yml"));//create rules
Rules rules =MVELRuleFactory.createRulesFrom(inputStreamReader);//fire rules
Facts facts = newFacts();
DiseaseModel diseaseModel= new DiseaseModel("ssss化疗");
String input="ssss化疗";
facts.put("diseaseModel", diseaseModel);
fizzBuzzEngine.fire(rules, facts);
System.out.println(diseaseModel.getResult());
}
}
二、使用easy-rules返回数据对象
easy-rules的返回结果中只能使用void方法，不能直接返回Object。否则报错：
Exception in thread "main" java.lang.IllegalArgumentException: Action method 'public java.lang.String org.easy.rules.anno.RuleClass$FizzRule.printFizz()' defined in rule 'org.songdan.easy.rules.anno.RuleClass$FizzRule' must be public, must return void type and may have parameters annotated with @Fact (and/or exactly one parameter of type or extending Facts).
此时可以将输入定义为一个实体类，在action中，直接修改需要修改的内容即可，如下：
---
name: "rule_1_对症治疗"
description: "print fizz if the number is multiple of 5"
priority: 1
condition: "diseaseModel.getInput().contains(\"对症治疗\")"
actions:
- "diseaseModel.result = \"对症治疗\")"
---
name: "rule_2_子宫平滑肌瘤"
description: "print buzz if the number is multiple of 7"
priority: 2
condition: "diseaseModel.getInput().contains(\"子宫平滑肌瘤\")"
actions:
- "diseaseModel.result = \"子宫平滑肌瘤\")"
---
name: "rule_3_化学治疗"
description: "diseaseModel.getInput().contains(\"化疗\") "
priority: 3
condition: "diseaseModel.getInput().contains(\"化疗\") || input.contains(\"化学治疗\")"
actions:
- "diseaseModel.result = \"化学治疗\""