1 Flowable工作流简介和初体验

1 简介 Flowable 官网地址： https://flowable.com/open - source/ Flowable 项目提供了一系列紧凑且高效的开源业务流程引擎。它们为开发人员、系统管理员和业务用户提供了一个工作流和业务流程管理（BPM ）平台。 Flowable 项目的核心是一个快速、经过测试的动态 BPMN 流程引擎，以及附带的 DMN 决策表和 CMMN 案例管理引擎，这些引擎都是用Java 语言编写的。 Flowable 遵守 Apache2.0 许可的开放协议，这是一个开源的组织。

2.1 Flowable初体验 2.1.1 Flowable是什么？

Flowable是一个用java语言编写的轻量级业务流程引擎。它允许部署遵守BPMN 2.0（一种工业的流程定义XML标准）规范的流程定义。通过流程定义，可以创建流程实例，通过流程实例可以执行查询、历史数据查询和相关流程数据查看等。文章下面会循序渐进介绍一些相关概念，并通过API展示让你慢慢熟悉，达到最终可以很好使用。 Flowable在构建项目的时候非常灵活，你可以再项目中把JAR包作为依赖使用它，也可以把它单独作为一个应用使用。

2.1.2 Flowable 和 Activiti

Flowable是Activiti（Alfresco的注册商标）的一个分支。在以下所有部分中，您将注意到包名、配置文件等都使用flowable。

2.1.3 构建命令行应用程序 2.1.3.1 创建一个流程引擎

使用开发工具idea构建一个简单的maven项目，创建项目流程如下：

选择 New -> Module

填写ArtifactId，这里填写的是flowable-holiday，名称填写完成以后点击右下角的Next按钮

进到下面的界面，点击Finish完成项目创建

到此我们创建成功了一个Maven的Module项目，项目的整体结构如下：

打开新建Module中的pom.xml在里面加上如下依赖：

org.flowable
flowable-engine
6.6.0

com.h2database
h2
1.3.176

选中pom.xml点击鼠标右键，选中Maven-> Reimport，重新加载一下pom文件，下载所需要的依赖。

在新建Module下面新建一个HolidayRequest.java的文件：

package com.dream21th.flowable;

import org.flowable.engine.ProcessEngine;
import org.flowable.engine.ProcessEngineConfiguration;
import org.flowable.engine.impl.cfg.StandaloneProcessEngineConfiguration;


public class HolidayRequest {

    public static void main(String[] args) {
        ProcessEngineConfiguration cfg = new StandaloneProcessEngineConfiguration()
                .setJdbcUrl("jdbc:h2:mem:flowable;DB_CLOSE_DELAY=-1")
                .setJdbcUsername("sa")
                .setJdbcPassword("")
                .setJdbcDriver("org.h2.Driver")
                .setDatabaseSchemaUpdate(ProcessEngineConfiguration.DB_SCHEMA_UPDATE_TRUE);

        ProcessEngine processEngine = cfg.buildProcessEngine();
    }
}

运行上面代码，控制台输出如下内容：

从上面控制台输出的内容来看，也没有什么有用的信息，我们可以增加一些日志的输出，在pom.xml文件中新增下面依赖：


  org.slf4j
  slf4j-api
  1.7.30


  org.slf4j
  slf4j-log4j12
  1.7.30

在src/main/resources目录下面新建文件log4j.properties。重新运行上面的main方法，控制台输出如下内容：

到此，我们创建一个简单的流程引擎。

2.1.3.2 部署一个流程定义

下面我们部署一个简单的请假的流程定义，流程定义文件是一个标准的XML文件，他们遵循BPMN 2.0规范。下面是本次部署流程定义的流程图：

下图对上面流程定义中的图标做了一些说明，具体含义建下图：

在src/main/resources下面创建一个holiday-request.bpmn20.xml文件，文件内容如下：

在上面的HolidayRequest.java增加代码后的整体代码如下：

package com.dream21th.flowable;

import org.flowable.engine.ProcessEngine;
import org.flowable.engine.ProcessEngineConfiguration;
import org.flowable.engine.RepositoryService;
import org.flowable.engine.impl.cfg.StandaloneProcessEngineConfiguration;
import org.flowable.engine.repository.Deployment;
import org.flowable.engine.repository.ProcessDefinition;


public class HolidayRequest {

    public static void main(String[] args) {
        ProcessEngineConfiguration cfg = new StandaloneProcessEngineConfiguration()
                .setJdbcUrl("jdbc:h2:mem:flowable;DB_CLOSE_DELAY=-1")
                .setJdbcUsername("sa")
                .setJdbcPassword("")
                .setJdbcDriver("org.h2.Driver")
                .setDatabaseSchemaUpdate(ProcessEngineConfiguration.DB_SCHEMA_UPDATE_TRUE);

        ProcessEngine processEngine = cfg.buildProcessEngine();

        
        RepositoryService repositoryService = processEngine.getRepositoryService();
        Deployment deployment = repositoryService.createDeployment()
                .addClasspathResource("holiday-request.bpmn20.xml")
                .deploy();

        
        ProcessDefinition processDefinition = repositoryService.createProcessDefinitionQuery()
                .deploymentId(deployment.getId())
                .singleResult();
        System.out.println("Found process definition : " + processDefinition.getName());
    }
}

2.1.3.3 启动一个流程实例

上面我们部署了一个流程定义，流程定义的key是holidayRequest，下面我们可以通过流程定义的key来开启一个流程实例。在main方法中新增下面代码，主要是控制在键盘上输入一些参数。

Scanner scanner= new Scanner(System.in);

System.out.println("Who are you?");
String employee = scanner.nextLine();

System.out.println("How many holidays do you want to request?");
Integer nrOfHolidays = Integer.valueOf(scanner.nextLine());

System.out.println("Why do you need them?");
String description = scanner.nextLine();

通过下面代码要开启一个流程实例

RuntimeService runtimeService = processEngine.getRuntimeService();

Map variables = new HashMap();
variables.put("employee", employee);
variables.put("nrOfHolidays", nrOfHolidays);
variables.put("description", description);
ProcessInstance processInstance =
  runtimeService.startProcessInstanceByKey("holidayRequest", variables);
System.out.println(processInstance.getId());

添加代码后的main方法的整体内容如下：

package com.dream21th.flowable;

import org.flowable.engine.ProcessEngine;
import org.flowable.engine.ProcessEngineConfiguration;
import org.flowable.engine.RepositoryService;
import org.flowable.engine.RuntimeService;
import org.flowable.engine.impl.cfg.StandaloneProcessEngineConfiguration;
import org.flowable.engine.repository.Deployment;
import org.flowable.engine.repository.ProcessDefinition;
import org.flowable.engine.runtime.ProcessInstance;

import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;


public class HolidayRequest {

    public static void main(String[] args) {
        ProcessEngineConfiguration cfg = new StandaloneProcessEngineConfiguration()
                .setJdbcUrl("jdbc:h2:mem:flowable;DB_CLOSE_DELAY=-1")
                .setJdbcUsername("sa")
                .setJdbcPassword("")
                .setJdbcDriver("org.h2.Driver")
                .setDatabaseSchemaUpdate(ProcessEngineConfiguration.DB_SCHEMA_UPDATE_TRUE);

        ProcessEngine processEngine = cfg.buildProcessEngine();

        
        RepositoryService repositoryService = processEngine.getRepositoryService();
        Deployment deployment = repositoryService.createDeployment()
                .addClasspathResource("holiday-request.bpmn20.xml")
                .deploy();

        
        ProcessDefinition processDefinition = repositoryService.createProcessDefinitionQuery()
                .deploymentId(deployment.getId())
                .singleResult();
        System.out.println("Found process definition : " + processDefinition.getName());

        Scanner scanner= new Scanner(System.in);

        System.out.println("Who are you?");
        String employee = scanner.nextLine();

        System.out.println("How many holidays do you want to request?");
        Integer nrOfHolidays = Integer.valueOf(scanner.nextLine());

        System.out.println("Why do you need them?");
        String description = scanner.nextLine();

        RuntimeService runtimeService = processEngine.getRuntimeService();

        Map variables = new HashMap();
        variables.put("employee", employee);
        variables.put("nrOfHolidays", nrOfHolidays);
        variables.put("description", description);
        ProcessInstance processInstance =
                runtimeService.startProcessInstanceByKey("holidayRequest", variables);

        System.out.println(processInstance.getId());
    }

2.1.3.4 查询和完成一个任务

修改holiday-request.bpmn20.xml流程定义文件，修改后的内容如下：

在HolidayRequest.java代码中增加下面代码：

TaskService taskService = processEngine.getTaskService();
//查询候选组是managers的任务
List tasks = taskService.createTaskQuery().taskCandidateGroup("managers").list();
System.out.println("You have " + tasks.size() + " tasks:");
for (int i=0; i 
System.out.println("Which task would you like to complete?");
int taskIndex = Integer.valueOf(scanner.nextLine());
Task task = tasks.get(taskIndex - 1);
//查询任务的过程变量
Map processVariables = taskService.getVariables(task.getId());
System.out.println(processVariables.get("employee") + " wants " +
    processVariables.get("nrOfHolidays") + " of holidays. Do you approve this?"); 
boolean approved = scanner.nextLine().toLowerCase().equals("y");
variables = new HashMap();
variables.put("approved", approved);
//完成任务
taskService.complete(task.getId(), variables); 
执行控制台输出如下： 
 
2.1.3.5 写一个JavaDelegate 
在自动任务中，通常需要写一个代理类，主要如： 
 
 代理类的内容如下： 
package com.dream21th.flowable;

import org.flowable.engine.delegate.DelegateExecution;
import org.flowable.engine.delegate.JavaDelegate;


public class CallExternalSystemDelegate implements JavaDelegate {

    public void execute(DelegateExecution delegateExecution) {
        System.out.println("Calling the external system for employee "
                + delegateExecution.getVariable("employee"));
    }
} 
执行的结果如下： 
 
2.1.3.6 查询历史数据 
流程实例执行中或者执行完成，我们可以通过下面的代码查询历史数据 
HistoryService historyService = processEngine.getHistoryService();
List activities =
  historyService.createHistoricActivityInstanceQuery()
   .processInstanceId(processInstance.getId())
   .finished()
   .orderByHistoricActivityInstanceEndTime().asc()
   .list();

for (HistoricActivityInstance activity : activities) {
  System.out.println(activity.getActivityId() + " took "
    + activity.getDurationInMillis() + " milliseconds");
} 
 整体代码如下: 
package com.dream21th.flowable;

import org.flowable.engine.*;
import org.flowable.engine.history.HistoricActivityInstance;
import org.flowable.engine.impl.cfg.StandaloneProcessEngineConfiguration;
import org.flowable.engine.repository.Deployment;
import org.flowable.engine.repository.ProcessDefinition;
import org.flowable.engine.runtime.ProcessInstance;
import org.flowable.task.api.Task;

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


public class HolidayRequest {

    public static void main(String[] args) {
        ProcessEngineConfiguration cfg = new StandaloneProcessEngineConfiguration()
                .setJdbcUrl("jdbc:h2:mem:flowable;DB_CLOSE_DELAY=-1")
                .setJdbcUsername("sa")
                .setJdbcPassword("")
                .setJdbcDriver("org.h2.Driver")
                .setDatabaseSchemaUpdate(ProcessEngineConfiguration.DB_SCHEMA_UPDATE_TRUE);

        ProcessEngine processEngine = cfg.buildProcessEngine();

        
        RepositoryService repositoryService = processEngine.getRepositoryService();
        Deployment deployment = repositoryService.createDeployment()
                .addClasspathResource("holiday-request.bpmn20.xml")
                .deploy();

        
        ProcessDefinition processDefinition = repositoryService.createProcessDefinitionQuery()
                .deploymentId(deployment.getId())
                .singleResult();
        System.out.println("Found process definition : " + processDefinition.getName());

        Scanner scanner= new Scanner(System.in);

        System.out.println("Who are you?");
        String employee = scanner.nextLine();

        System.out.println("How many holidays do you want to request?");
        Integer nrOfHolidays = Integer.valueOf(scanner.nextLine());

        System.out.println("Why do you need them?");
        String description = scanner.nextLine();

        RuntimeService runtimeService = processEngine.getRuntimeService();

        Map variables = new HashMap();
        variables.put("employee", employee);
        variables.put("nrOfHolidays", nrOfHolidays);
        variables.put("description", description);
        ProcessInstance processInstance =
                runtimeService.startProcessInstanceByKey("holidayRequest", variables);

        System.out.println(processInstance.getId());


        TaskService taskService = processEngine.getTaskService();
        //查询候选组是managers的任务
        List tasks = taskService.createTaskQuery().taskCandidateGroup("managers").list();
        System.out.println("You have " + tasks.size() + " tasks:");
        for (int i=0; i processVariables = taskService.getVariables(task.getId());
        System.out.println(processVariables.get("employee") + " wants " +
                processVariables.get("nrOfHolidays") + " of holidays. Do you approve this?");


        boolean approved = scanner.nextLine().toLowerCase().equals("y");
        variables = new HashMap();
        variables.put("approved", approved);
        //完成任务
        taskService.complete(task.getId(), variables);

        HistoryService historyService = processEngine.getHistoryService();
        List activities =
                historyService.createHistoricActivityInstanceQuery()
                        .processInstanceId(processInstance.getId())
                        .finished()
                        .orderByHistoricActivityInstanceEndTime().asc()
                        .list();

        for (HistoricActivityInstance activity : activities) {
            System.out.println(activity.getActivityId() + " took "
                    + activity.getDurationInMillis() + " milliseconds");
        }
    }
} 
执行结果

1 Flowable工作流简介和初体验

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