35、Activiti整合规则引擎Drools

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日常生活是由规则驱动的。红灯停绿灯行，这是我们的交通规则；我们站着往上跳，最终还是要落下来，这是地球的引力规则。规则在生活中无处不在。软件开发中我们也需要规则，满足什么规则应该进入什么分支。如果做过风控系统，就知道风控系统里存在非常多的规则（比如：age < 16 || age > 50 -> REJECT ）。最便捷的实现就是用 if-else 来写，但是随着规则的增加以及需求的变动，代码将变得越来越难阅读和理解，如果再去修改这些代码，然后测试不够充分的话，将产生严重的生产事故。这时候就要引入Drools等规则引擎了。Drools就是为了解决业务代码和业务规则分离的引擎。
        要使用Drools规则引擎，需要先安装安装JBoss Drools Support插件，这里就不多说怎么安装安装JBoss Drools Support插件。下载地址如下：

https://download.jboss.org/drools/release/7.3.0.Final/droolsjbpm-tools-distribution-7.3.0.Final.zip

1、 新建项目sc-activiti-drools，对应的pom.xml文件如下

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>

        <groupId>com.sc</groupId>
        <artifactId>sc-activiti-drools</artifactId>
        <version>0.0.1-SNAPSHOT</version>

        <name>sc-activiti-drools</name>
        <!-- FIXME change it to the project's website -->
        <url>http://www.example.com</url>

        <properties>
                <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
                <maven.compiler.source>1.8</maven.compiler.source>
                <maven.compiler.target>1.8</maven.compiler.target>
        </properties>

        <parent>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-parent</artifactId>
                <version>2.0.4.RELEASE</version>
        </parent>

        <dependencyManagement>
                <dependencies>
                        <dependency>
                                <groupId>org.springframework.cloud</groupId>
                                <artifactId>spring-cloud-dependencies</artifactId>
                                <version>Finchley.RELEASE</version>
                                <type>pom</type>
                                <scope>import</scope>
                        </dependency>

                </dependencies>
        </dependencyManagement>

        <dependencies>
                <dependency>
                        <groupId>org.springframework.boot</groupId>
                        <artifactId>spring-boot-starter-web</artifactId>
                </dependency>

                <dependency>
                        <groupId>org.activiti</groupId>
                        <artifactId>activiti-engine</artifactId>
                        <version>6.0.0</version>
                </dependency>

                <dependency>
                        <groupId>org.activiti</groupId>
                        <artifactId>activiti-spring</artifactId>
                        <version>6.0.0</version>
                </dependency>
                <dependency>
                        <groupId>mysql</groupId>
                        <artifactId>mysql-connector-java</artifactId>
                        <scope>runtime</scope>
                </dependency>

                <dependency>
                        <groupId>org.drools</groupId>
                        <artifactId>drools-core</artifactId>
                        <version>7.0.0.Final</version>
                </dependency>

                <dependency>
                        <groupId>org.drools</groupId>
                        <artifactId>drools-compiler</artifactId>
                        <version>7.0.0.Final</version>
                </dependency>

                <dependency>
                        <groupId>org.drools</groupId>
                        <artifactId>knowledge-api</artifactId>
                        <version>6.5.0.Final</version>
                </dependency>

        </dependencies>

        <build>
                <pluginManagement><!-- lock down plugins versions to avoid using Maven 
                                defaults (may be moved to parent pom) -->
                        <plugins>
                                <plugin>
                                        <artifactId>maven-clean-plugin</artifactId>
                                        <version>3.0.0</version>
                                </plugin>
                                <!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_jar_packaging -->
                                <plugin>
                                        <artifactId>maven-resources-plugin</artifactId>
                                        <version>3.0.2</version>
                                </plugin>
                                <plugin>
                                        <artifactId>maven-compiler-plugin</artifactId>
                                        <version>3.7.0</version>
                                </plugin>
                                <plugin>
                                        <artifactId>maven-surefire-plugin</artifactId>
                                        <version>2.20.1</version>
                                </plugin>
                                <plugin>
                                        <artifactId>maven-jar-plugin</artifactId>
                                        <version>3.0.2</version>
                                </plugin>
                                <plugin>
                                        <artifactId>maven-install-plugin</artifactId>
                                        <version>2.5.2</version>
                                </plugin>
                                <plugin>
                                        <artifactId>maven-deploy-plugin</artifactId>
                                        <version>2.8.2</version>
                                </plugin>
                        </plugins>
                </pluginManagement>
        </build>
</project>

2、新建spring配置文件application.yml

spring:
    datasource:
        driver-class-name: com.mysql.jdbc.Driver
        url: jdbc:mysql://127.0.0.1:3306/sc?characterEncoding=utf8&useSSL=true
        username: root
        password: root
    activiti:
        check-process-definitions: false #自动部署验证设置:true-开启（默认）、false-关闭
    jpa:
        properties:
            hibernate:
                hbm2ddl:
                    auto: update
    show-sql: true

server:
    port: 8081
    context-path: /
    session:
        timeout: 10
    tomcat:
        uri-encoding: UTF-8

3、新建activiti对应的配置文件activiti.cfg.xml

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://www.springframework.org/schema/beans   http://www.springframework.org/schema/beans/spring-beans.xsd">

        <bean id="dataSource" class="org.springframework.jdbc.datasource.SimpleDriverDataSource">
                <property name="driverClass" value="com.mysql.jdbc.Driver" />
                <property name="url" value="jdbc:mysql://localhost:3306/act?useUnicode=true&amp;characterEncoding=UTF-8" />
                <property name="username" value="root" />
                <property name="password" value="root" />
        </bean>

        <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
                <property name="dataSource" ref="dataSource" />
        </bean>

        <bean id="processEngineConfiguration" class="org.activiti.spring.SpringProcessEngineConfiguration">
                <property name="dataSource" ref="dataSource" />
                <property name="transactionManager" ref="transactionManager" />
                <property name="databaseSchemaUpdate" value="true" />
                <property name="customPostDeployers">
                        <list> 
                                    <bean class="org.activiti.engine.impl.rules.RulesDeployer" />
                        </list> 
                </property>
                <!-- 
                        <property name="deploymentResources" value="classpath*:/bpmn/*.bpmn" />  
                 -->
        </bean>

        <bean id="processEngine" class="org.activiti.spring.ProcessEngineFactoryBean">
                <property name="processEngineConfiguration" ref="processEngineConfiguration" />
        </bean>

        <bean id="repositoryService" factory-bean="processEngine" factory-method="getRepositoryService" />
        <bean id="runtimeService" factory-bean="processEngine" factory-method="getRuntimeService" />
        <bean id="taskService" factory-bean="processEngine" factory-method="getTaskService" />
        <bean id="historyService" factory-bean="processEngine" factory-method="getHistoryService" />
        <bean id="managementService" factory-bean="processEngine" factory-method="getManagementService" />

</beans>

4、新建请假流程对应的bpmn文件如下

<?xml version="1.0" encoding="UTF-8"?>
<definitions xmlns="http://www.omg.org/spec/BPMN/20100524/MODEL"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"
        xmlns:activiti="http://activiti.org/bpmn" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI"
        xmlns:omgdc="http://www.omg.org/spec/DD/20100524/DC" xmlns:omgdi="http://www.omg.org/spec/DD/20100524/DI"
        typeLanguage="http://www.w3.org/2001/XMLSchema" expressionLanguage="http://www.w3.org/1999/XPath"
        targetNamespace="http://www.activiti.org/test">

        <process id="leave" name="请假审批" isExecutable="true">
                <startEvent id="startevent1" name="Start"></startEvent>
                <endEvent id="endevent1" name="End"></endEvent>
                <userTask id="usertask1" name="部门经理审批"></userTask>
                <busine***uleTask id="busine***uletask1" name="天数判断" activiti:ruleVariablesInput="${leave}" activiti:rules="leave1,leave2" activiti:resultVariable="reason"></busine***uleTask>
                <serviceTask id="servicetask1" name="获取变量" activiti:class="sc.ad.service.DroolsService"></serviceTask>
                <userTask id="usertask2" name="HR审批"></userTask>
                <sequenceFlow id="flow1" sourceRef="startevent1" targetRef="usertask1"></sequenceFlow>
                <sequenceFlow id="flow2" sourceRef="usertask1" targetRef="busine***uletask1"></sequenceFlow>
                <sequenceFlow id="flow3" sourceRef="busine***uletask1" targetRef="servicetask1"></sequenceFlow>
                <userTask id="usertask3" name="总经理审批"></userTask>
                <sequenceFlow id="flow4" sourceRef="servicetask1" targetRef="usertask3">
                        <conditionExpression xsi:type="tFormalExpression"><![CDATA[${reason[0].total >= 10}]]></conditionExpression>
                </sequenceFlow>
                <sequenceFlow id="flow5" sourceRef="servicetask1" targetRef="usertask2">
                        <conditionExpression xsi:type="tFormalExpression"><![CDATA[${reason[0].total < 10}]]></conditionExpression>
                </sequenceFlow>
                <sequenceFlow id="flow6" sourceRef="usertask3" targetRef="usertask2"></sequenceFlow>
                <sequenceFlow id="flow7" sourceRef="usertask2" targetRef="endevent1"></sequenceFlow>
        </process>
</definitions>

bpmn文件对应的图如下

5、新建规则文件leave.drl

package sc.ad;

import sc.ad.model.Leave;

rule "leave1"
        when
                u : Leave(day < 3);
        then
                u.setTotal(u.getDay() + 2);
end

rule "leave2"
        when
                u : Leave(day >= 3);
        then
                u.setTotal(u.getDay() + 5);
end

对应的图如下

6、新建springboot启动类文件

package sc.ad;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ImportResource;

@SpringBootApplication
@ImportResource("activiti.cfg.xml")
public class ActivitiDroolsApp {
        public static void main(String[] args)
        {
                SpringApplication.run(ActivitiDroolsApp.class, args);
        }

}

7、新建一个controller，用来发起请假请求

package sc.ad.controller;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.activiti.engine.RepositoryService;
import org.activiti.engine.RuntimeService;
import org.activiti.engine.TaskService;
import org.activiti.engine.repository.Deployment;
import org.activiti.engine.repository.DeploymentBuilder;
import org.activiti.engine.repository.ProcessDefinition;
import org.activiti.engine.runtime.ProcessInstance;
import org.activiti.engine.task.Task;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import sc.ad.model.Leave;

@RestController
public class ADController {

        @Autowired
        private RepositoryService repositoryService;

        @Autowired
        private RuntimeService runtimeService;

        @Autowired
        private TaskService taskService;

//    @RequestMapping("/ad")
//    public void ad() {
//
//        // 根据bpmn文件部署流程
//        Deployment deployment = repositoryService.createDeployment()
//                .addClasspathResource("holiday.bpmn").deploy();
//        // 获取流程定义
//        ProcessDefinition processDefinition = repositoryService
//                .createProcessDefinitionQuery()
//                .deploymentId(deployment.getId()).singleResult();
//        // 启动流程定义，返回流程实例
//        ProcessInstance pi = runtimeService
//                .startProcessInstanceById(processDefinition.getId());
//        String processId = pi.getId();
//        System.out.println("流程创建成功，当前流程实例ID：" + processId);
//
//        Task task = taskService.createTaskQuery().processInstanceId(processId)
//                .singleResult();
//        System.out.println("第一次执行前，任务名称：" + task.getName());
//        taskService.complete(task.getId());
//
//        task = taskService.createTaskQuery().processInstanceId(processId)
//                .singleResult();
//        System.out.println("第二次执行前，任务名称：" + task.getName());
//        taskService.complete(task.getId());
//
//        task = taskService.createTaskQuery().processInstanceId(processId)
//                .singleResult();
//        System.out.println("task为null，任务执行完毕：" + task);
//    }

        @RequestMapping("/drl")
        public void drl() {
                /**
                 * 注意这里：必须要把drl文件一起deploy
                 */
                DeploymentBuilder deploy = repositoryService.createDeployment();
                deploy.addClasspathResource("leave.bpmn").addClasspathResource("leave.drl");
                deploy.deploy();
                ProcessInstance pi = runtimeService.startProcessInstanceByKey("leave");
                Map<String, Object> vars = new HashMap<String, Object>();  
                vars.put("leave", new Leave("白展堂", 12));
                /**
                 * 当前任务
                 */
                List<Task> tasks = taskService.createTaskQuery().processInstanceId(pi.getId()).list();
                for(Task task : tasks)
                {
                        System.out.println(task.getId() + " , " + task.getName());
                        taskService.complete(task.getId(), vars);
                }
                /**
                 * 下一步任务
                 */
                tasks = taskService.createTaskQuery().processInstanceId(pi.getId()).list();
                for(Task task : tasks)
                {
                        System.out.println(task.getId() + " , " + task.getName());
                }
        }
}

8、启动并验证规则是否生效
从日志中看启动成功

访问http://127.0.0.1:8081/drl后，再次查看日志：

把修改controller的如下代码
        vars.put("leave", new Leave("白展堂", 12));
改成
     vars.put("leave", new Leave("乔峰", 2));

可以看到规则文件的规则已经生效：

来源：oschina

链接：https://my.oschina.net/u/4409653/blog/4263088