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&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：