Drools規則引擎-Drools入門案例

echo編輯整理，歡迎轉載，轉載請聲明文章來源。歡迎添加echo微信(微信號：t2421499075) 交流學習。java

Drools的實現並不難，關鍵是瞭解他的語法便可web

入門案例

建立一個簡單的SpringBoot項目

選擇依賴的時候，添加一個web依賴便可

在新項目的pom.xml中添加drools的相關依賴

<properties>
    <java.version>1.8</java.version>
    <drools.version>7.14.0.Final</drools.version>
</properties>
<dependencies>
<!-- drools依賴 -->
    <dependency>
        <groupId>org.drools</groupId>
        <artifactId>drools-core</artifactId>
        <version>${drools.version}</version>
    </dependency>
    <dependency>
        <groupId>org.drools</groupId>
        <artifactId>drools-compiler</artifactId>
        <version>${drools.version}</version>
    </dependency>
    <!-- 決策表 -->
    <dependency>
        <groupId>org.drools</groupId>
        <artifactId>drools-decisiontables</artifactId>
        <version>${drools.version}</version>
    </dependency>
    <!-- 模板 -->
    <dependency>
        <groupId>org.drools</groupId>
        <artifactId>drools-templates</artifactId>
        <version>${drools.version}</version>
    </dependency>
    
    <dependency>
        <groupId>org.kie</groupId>
        <artifactId>kie-api</artifactId>
        <version>${drools.version}</version>
    </dependency>
</dependencies>

建立Kie相關 Bean 使其被spring管理

import org.kie.api.KieBase;
import org.kie.api.KieServices;
import org.kie.api.builder.KieBuilder;
import org.kie.api.builder.KieFileSystem;
import org.kie.api.builder.KieModule;
import org.kie.api.builder.KieRepository;
import org.kie.api.builder.ReleaseId;
import org.kie.api.runtime.KieContainer;
import org.kie.api.runtime.KieSession;
import org.kie.internal.io.ResourceFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;
import org.springframework.core.io.Resource;

import java.io.IOException;

/**
 * @author tang.sl
 * @date 2021-01-05 09:37
 */
@Configuration
public class KiaSessionConfig {

    private static final String RULES_PATH = "rules/";

    @Bean
    public KieFileSystem kieFileSystem() throws IOException {
        KieFileSystem kieFileSystem = getKieServices().newKieFileSystem();
        for (Resource file : getRuleFiles()) {
            kieFileSystem.write(ResourceFactory.newClassPathResource(RULES_PATH + file.getFilename(), "UTF-8"));
        }
        return kieFileSystem;
    }

    private Resource[] getRuleFiles() throws IOException {

        ResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();
        final Resource[] resources = resourcePatternResolver.getResources("classpath*:" + RULES_PATH + "**/*.*");
        return resources;

    }

    @Bean
    public KieContainer kieContainer() throws IOException {

        final KieRepository kieRepository = getKieServices().getRepository();
        kieRepository.addKieModule(new KieModule() {
            public ReleaseId getReleaseId() {
                return kieRepository.getDefaultReleaseId();
            }
        });

        KieBuilder kieBuilder = getKieServices().newKieBuilder(kieFileSystem());
        kieBuilder.buildAll();
        return getKieServices().newKieContainer(kieRepository.getDefaultReleaseId());

    }

    private KieServices getKieServices() {
        return KieServices.Factory.get();
    }

    @Bean
    public KieBase kieBase() throws IOException {
        return kieContainer().getKieBase();
    }

    @Bean
    public KieSession kieSession() throws IOException {
        return kieContainer().newKieSession();
    }
}

到目前爲止，咱們的基本準備工做就已經完成了，咱們能夠建立實際的案例來使用Drools了。spring

根據前面的需求定義一個實體類

@Data
@ToString
@NoArgsConstructor
@AllArgsConstructor
public class User {
    private String name;
    private String age;
    private String address;
    private String phone;
    private String sex;
}

建立drl規則文件根據前幾篇文章描述的內容，咱們來設計一個規則文件。文件放在resources目錄下面，在該目錄下面建立一個rules統一存放後面全部的rule文件

package com.echo.drools.dto
import com.echo.drools.dto.User
dialect "java"

rule "address eq beijing"
    when
        $user: User(address == "北京")
    then
         System.out.println($user.getName() + "是個北漂");
    end

rule "address eq shanghai"
    when
        $user: User(address == "上海")
    then
         System.out.println($user.getName() + "是個上漂");
    end

而後咱們就能夠來測試使用這個規則

import com.echo.drools.dto.User;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.Test;
import org.kie.api.runtime.KieSession;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest
class DroolsApplicationTests {

    @Autowired
    private KieSession session;

    @Test
    void contextLoads() {
        User user = new User();
        user.setAddress("北京");
        user.setAge("20");
        user.setName("echo");
        user.setPhone("136123456");
        user.setSex("1");
        // 插入用戶
        session.insert(user);
        // 執行規則
        session.fireAllRules();
    }

    /**
     * 記得執行完成以後釋放資源
     */
    @AfterEach
    public void runDispose() {
        session.dispose();
    }

}

屢次測試結果和咱們的符合咱們原有的預期，好比上面的實例，最終會在控制檯輸出「echo是北漂」。

注意：咱們這裏僅僅寫了兩個規則，而且也沒有寫對應的業務代碼，這個後面再講，僅僅只是一個入門展現案例。不要多糾結爲何沒有業務代碼api