EasyRules是一款基于Java的開(kāi)源的輕量級(jí)的規(guī)則引擎框架。它可以幫助開(kāi)發(fā)人員快速開(kāi)發(fā)并管理規(guī)則，實(shí)現(xiàn)應(yīng)用程序的自動(dòng)化決策。EasyRules框架非常易于使用，且可以與任何Java應(yīng)用程序無(wú)縫集成。在本文中，我們將對(duì)其進(jìn)行一個(gè)簡(jiǎn)單的封裝，以實(shí)現(xiàn)復(fù)雜的規(guī)則表達(dá)式匹配。
一、EasyRules的基本概念
EasyRules是一個(gè)基于規(guī)則的引擎，它基于規(guī)則引擎的常見(jiàn)原則和概念。以下是一些EasyRules框架中的重要概念：
- 規(guī)則（Rule）：規(guī)則是EasyRules框架中的核心概念，它用于描述應(yīng)用程序中需要遵循的規(guī)則。每個(gè)規(guī)則通常包含兩個(gè)部分：規(guī)則名稱(chēng)和規(guī)則條件。
- 規(guī)則條件（Condition）：規(guī)則條件定義了規(guī)則的前提條件。如果規(guī)則條件為true，則規(guī)則將被觸發(fā)執(zhí)行。否則，規(guī)則將被忽略。
- 規(guī)則動(dòng)作（Action）：規(guī)則動(dòng)作是在規(guī)則被觸發(fā)時(shí)執(zhí)行的一段代碼。它可以用于實(shí)現(xiàn)各種應(yīng)用程序邏輯，例如更新數(shù)據(jù)、發(fā)送消息等。
- 規(guī)則執(zhí)行（Rule Engine）：規(guī)則執(zhí)行是EasyRules框架的核心功能之一，它負(fù)責(zé)解析規(guī)則條件，并根據(jù)條件執(zhí)行相應(yīng)的規(guī)則動(dòng)作。
二、快速上手Demo
了解了easyRules的基本概念后，我們來(lái)寫(xiě)一個(gè)簡(jiǎn)單的demo：
假設(shè)我們有一個(gè)需求，根據(jù)用戶(hù)的年齡來(lái)決定是否可以購(gòu)買(mǎi)酒類(lèi)產(chǎn)品，如果用戶(hù)年齡小于18歲，則不能購(gòu)買(mǎi)酒類(lèi)產(chǎn)品。
首先，我們需要定義一個(gè)規(guī)則類(lèi)，繼承自org.jeasy.rules.annotation.Rule，如下所示：
import org.jeasy.rules.annotation.Condition;
import org.jeasy.rules.annotation.Fact;
import org.jeasy.rules.annotation.Rule;
@Rule(name = "age rule", description = "Check if user is of legal age to buy alcohol")
public class AgeRule {
@Condition
public boolean checkAge(@Fact("age") int age) {
return age >= 18;
}
}
在這個(gè)規(guī)則類(lèi)中，我們定義了一個(gè)名為“checkAge”的條件方法，它接受一個(gè)名為“age”的事實(shí)參數(shù)，并返回一個(gè)布爾值表示用戶(hù)是否滿(mǎn)足購(gòu)買(mǎi)酒類(lèi)產(chǎn)品的年齡要求。
接下來(lái)，我們需要?jiǎng)?chuàng)建一個(gè)規(guī)則引擎實(shí)例，并將規(guī)則類(lèi)添加到規(guī)則引擎中。代碼如下所示：
import org.jeasy.rules.api.Facts;
import org.jeasy.rules.api.Rules;
import org.jeasy.rules.core.RulesImpl;
import org.jeasy.rules.core.DefaultRulesEngine;
public class RuleEngineDemo {
public static void main(String[] args) {
AgeRule ageRule = new AgeRule();
Rules rules = new RulesImpl();
rules.register(ageRule);
DefaultRulesEngine rulesEngine = new DefaultRulesEngine();
Facts facts = new Facts();
facts.put("age", 20);
rulesEngine.fire(rules, facts);
}
}
在這個(gè)示例代碼中，我們創(chuàng)建了一個(gè)名為“ageRule”的規(guī)則對(duì)象，并將其注冊(cè)到名為“rules”的規(guī)則集合中。接著，我們創(chuàng)建了一個(gè)默認(rèn)的規(guī)則引擎實(shí)例，并創(chuàng)建了一個(gè)名為“facts”的事實(shí)對(duì)象，并將“age”和“20”作為鍵值對(duì)添加到事實(shí)對(duì)象中。最后，我們通過(guò)調(diào)用規(guī)則引擎的fire方法來(lái)啟動(dòng)規(guī)則引擎并觸發(fā)規(guī)則執(zhí)行。
三、easyRules工具類(lèi)
以上示例展示了如何快速的使用easyRule實(shí)現(xiàn)規(guī)則創(chuàng)建及調(diào)用的流程。但是如果我們有更復(fù)雜的場(chǎng)景，比如在數(shù)據(jù)質(zhì)量規(guī)則校驗(yàn)中，我們有如下的規(guī)則判斷：
[外鏈圖片轉(zhuǎn)存失敗,源站可能有防盜鏈機(jī)制,建議將圖片保存下來(lái)直接上傳(img-XJC0OufR-1685683113114)(/Users/casey/Library/Application Support/typora-user-images/image-20230329152414895.png)]
對(duì)于這種比較復(fù)雜且校驗(yàn)規(guī)則經(jīng)常會(huì)發(fā)生變化的規(guī)則，通過(guò)上述代碼就無(wú)法實(shí)現(xiàn)了，為此，我將對(duì)easyRule做進(jìn)一步的封裝，以達(dá)到此目的。
1. 定義常量類(lèi)
首先定義一個(gè)常量類(lèi)
package com.shsc.bigdata.indicator.monitor.common.constant;
public class EasyRulesConstants {
// 事實(shí)別名
public static final String FACT_ALIAS = "fact";
// 結(jié)果別名
public static final String RESULT_ALIAS = "result";
// and關(guān)系
public static final String RELATION_AND = "and";
// or關(guān)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 = "||";
}
2. 定義枚舉類(lèi)
定義一個(gè)枚舉類(lèi)，羅列出常用的運(yùn)算符
package com.shsc.bigdata.indicator.monitor.common.enums;
public enum EasyRulesOperation {
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", "介于之間"),
OUT_OF_RANGE("OUT_OF_RANGE", "%s >= %s || %s >= %s", "超出范圍"),
CONTAINS("CONTAINS", "%s.contains(\"%s\")", "包含"),
STARTSWITH("STARTSWITH", "%s.startsWith(\"%s\")", "前綴"),
ENDSWITH("ENDSWITH", "%s.endsWith(\"%s\")", "后綴"),
;
public static EasyRulesOperation getOperationByOperator(String operator) {
EasyRulesOperation[] list = EasyRulesOperation.values();
for (EasyRulesOperation 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;
EasyRulesOperation(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;
}
}
3. 工具類(lèi)
package com.shsc.bigdata.indicator.monitor.common.utils.easyRules;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import com.shsc.bigdata.indicator.monitor.common.enums.EasyRulesOperation;
import lombok.Data;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.ObjectUtils;
import org.apache.commons.lang3.StringUtils;
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.mvel.MVELRule;
import static com.shsc.bigdata.indicator.monitor.common.constant.EasyRulesConstants.*;
@Slf4j
public class EasyRulesUtil {
/**
* 執(zhí)行規(guī)則匹配
* @param fact 事實(shí)json
* @param ruleModel 規(guī)則模型
*/
public static RuleResult match(JSONObject fact, RuleModel ruleModel){
// 結(jié)果
RuleResult result = new RuleResult();
result.setRuleId(ruleModel.getRuleId());
// 規(guī)則實(shí)例
Facts facts = new Facts();
facts.put(FACT_ALIAS, fact);
facts.put(RESULT_ALIAS, result);
// 規(guī)則內(nèi)容
org.jeasy.rules.api.Rule mvelrule = new MVELRule()
.name(ruleModel.getRuleName())
.description(ruleModel.getDescription())
.when(ruleModel.getWhenExpression())
.then(ruleModel.getThenExpression());
// 規(guī)則集合
Rules rules = new Rules();
// 將規(guī)則添加到集合
rules.register(mvelrule);
// 創(chuàng)建規(guī)則執(zhí)行引擎，并執(zhí)行規(guī)則
RulesEngine rulesEngine = new DefaultRulesEngine();
rulesEngine.fire(rules, facts);
return result;
}
/**
* 構(gòu)建mvel條件表達(dá)式
* @param json 節(jié)點(diǎn)json，例如：
* {
* "type": "EXPRESSION",
* "operator": "LESS_THAN",
* "metricName": "NORMAL_NUMBER",
* "value": "11",
* "children": []
* }
*/
public static String buildWhenExpression(JSONObject json) {
StringBuilder mvelExpression = 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);
mvelExpression.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 childrenExpression = new StringBuilder();
for (int i = 0; i < children.size(); i++) {
JSONObject child = children.getJSONObject(i);
// 遞歸構(gòu)建單個(gè)規(guī)則條件
String childExpression = buildWhenExpression(child);
if (!childExpression.isEmpty()) {
if (childrenExpression.length() > 0) {
childrenExpression.append(SYMBOL_SPACE).append(operator).append(SYMBOL_SPACE);
}
childrenExpression.append(LEFT_BRACKETS).append(childExpression).append(RIGHT_BRACKETS);
}
}
mvelExpression.append(childrenExpression);
break;
default:
break;
}
return mvelExpression.toString();
}
/**
* 構(gòu)建mvel結(jié)果表達(dá)式
*/
public static String buildThenExpression() {
StringBuilder expression = new StringBuilder();
expression.append(RESULT_ALIAS).append(".setValue(\"").append(MATCH_SUCCESS_MESSAGE).append("\");");
log.info("thenExpression: {}", expression);
return expression.toString();
}
/**
* 轉(zhuǎn)換條件連接符
* @param relation 條件連接符
*/
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;
}
/**
* 構(gòu)建mvel表達(dá)式
* @param operator 操作符
* @param fieldName 字段名稱(chēng)
* @param value 字段值
*/
private static String buildOperatorExpress(String operator, String fieldName, Object value) {
EasyRulesOperation operation = EasyRulesOperation.getOperationByOperator(operator);
if (ObjectUtils.isNotEmpty(operation)) {
String expression = operation.getExpression();
return String.format(expression, buildValueExpress(fieldName), value);
}
return SYMBOL_EMPTY;
}
/**
* 構(gòu)建mvel取值表達(dá)式
* @param fieldName 字段名稱(chēng)
*/
private static String buildValueExpress(String fieldName) {
return String.format("%s.get(\"%s\")", FACT_ALIAS, fieldName);
}
@Data
public static class RuleModel {
private String ruleId;
String ruleName;
String description;
String whenExpression;
String thenExpression;
}
@Data
public static class RuleResult {
// 規(guī)則主鍵
private String ruleId;
// 是否匹配, 默認(rèn)false
boolean isMatch = false;
// 匹配信息，默認(rèn)為匹配失敗
String message = "匹配失敗";
/**
* 匹配成功后設(shè)置成功信息
*/
public void setValue(String message){
this.message = message;
this.isMatch = true;
}
}
}
4. 測(cè)試
package com.shsc.bigdata.indicator.monitor.common;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.shsc.bigdata.indicator.monitor.common.utils.easyRules.EasyRulesUtil;
import lombok.extern.slf4j.Slf4j;
@Slf4j
public class TestEasyRules {
public static void main(String[] args) {
// 1. 新增規(guī)則
EasyRulesUtil.RuleModel ruleModel = new EasyRulesUtil.RuleModel();
ruleModel.setRuleId("1");
ruleModel.setRuleName("rule1");
ruleModel.setDescription("測(cè)試規(guī)則");
// 2. 設(shè)置規(guī)則條件
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. 設(shè)置fact
String whenExpression = EasyRulesUtil.buildWhenExpression(conditionJson.getJSONObject("validateCondition"));
log.info("whenExpression：{}", whenExpression);
ruleModel.setWhenExpression(whenExpression);
// 4. 設(shè)置結(jié)果表達(dá)式
ruleModel.setThenExpression(EasyRulesUtil.buildThenExpression());
// 5. 設(shè)置匹配條件
JSONObject json = new JSONObject();
json.put("NORMAL_NUMBER", "10");
json.put("ERROR_NUMBER", 10);
json.put("省=陜西；市=西安;", 100);
// 6. 調(diào)用規(guī)則匹配
EasyRulesUtil.RuleResult result = EasyRulesUtil.match(json, ruleModel);
System.out.println(result);
}
}
上面的例子中，我使用了MVEL表達(dá)式語(yǔ)言實(shí)現(xiàn)了動(dòng)態(tài)規(guī)則，關(guān)于MVEL的知識(shí)請(qǐng)翻閱歷史文章查看。然后傳入了一個(gè)比較復(fù)雜的多層級(jí)的規(guī)則表達(dá)式，測(cè)試結(jié)果如下：
15:30:29.915 [main] INFO com.shsc.bigdata.indicator.monitor.common.EasyRules - whenExpression：(fact.get("NORMAL_NUMBER") < 11) || (fact.get("ERROR_NUMBER") <= 11) || ((fact.get("NORMAL_NUMBER") > 10) || (fact.get("ERROR_NUMBER") > 100) || ((fact.get("NORMAL_NUMBER") == 1) || (fact.get("ERROR_NUMBER") == 1)))
15:30:29.919 [main] INFO com.shsc.bigdata.indicator.monitor.common.utils.easyRules.EasyRulesUtil - thenExpression: result.setValue("匹配成功");
15:30:30.085 [main] DEBUG org.jeasy.rules.core.DefaultRulesEngine - Engine parameters { skipOnFirstAppliedRule = false, skipOnFirstNonTriggeredRule = false, skipOnFirstFailedRule = false, priorityThreshold = 2147483647 }
15:30:30.085 [main] DEBUG org.jeasy.rules.core.DefaultRulesEngine - Registered rules:
15:30:30.086 [main] DEBUG org.jeasy.rules.core.DefaultRulesEngine - Rule { name = 'rule1', description = '測(cè)試規(guī)則', priority = '2147483646'}
15:30:30.086 [main] DEBUG org.jeasy.rules.core.DefaultRulesEngine - Known facts:
15:30:30.086 [main] DEBUG org.jeasy.rules.core.DefaultRulesEngine - Fact{name='result', value=EasyRulesUtil.RuleResult(ruleId=1, isMatch=false, message=匹配失敗)}
15:30:30.086 [main] DEBUG org.jeasy.rules.core.DefaultRulesEngine - Fact{name='fact', value={"ERROR_NUMBER":10,"NORMAL_NUMBER":"10","省=陜西；市=西安;":100}}
15:30:30.096 [main] DEBUG org.jeasy.rules.core.DefaultRulesEngine - Rules evaluation started
15:30:30.178 [main] DEBUG org.jeasy.rules.core.DefaultRulesEngine - Rule 'rule1' triggered
15:30:30.187 [main] DEBUG org.jeasy.rules.core.DefaultRulesEngine - Rule 'rule1' performed successfully
EasyRulesUtil.RuleResult(ruleId=1, isMatch=true, message=匹配成功)
從上述日志可以看到，isMatch=true表示匹配成功：
EasyRulesUtil.RuleResult(ruleId=1, isMatch=true, message=匹配成功)
四、寫(xiě)在最后
通過(guò)以上對(duì)easyRules的封裝，我們可以實(shí)現(xiàn)復(fù)雜的規(guī)則表達(dá)式校驗(yàn)，只需要定義好表達(dá)式的json結(jié)構(gòu)以及匹配的條件即可。
PS：以上文章出自微信公眾號(hào)“毛毛小妖的筆記”。
查看更多原創(chuàng)內(nèi)容請(qǐng)?jiān)谖⑿殴娞?hào)搜索“毛毛小妖的筆記”即可關(guān)注。
