Activiti 快速入门指南（用Java编写服务任务）

用Java编写服务任务

如前所述，我们的流程具有“Generic and Automated Data Entry”活动（虚拟后端调用），当入职经验不超过3年时，将有条件地执行该活动，如所提供的，这是一个“脚本任务”。在这种情况下，执行一小段Javascript来说明系统处理步骤，我们将把这个脚本任务迁移到Java中，以说明Java的强大功能如何满足各种流程要求。

创建一个新的Java类，如下所示：

文件：$mvnProject/src/main/java/com/example/AutomatedDataDelegate.java

package com.example;

import java.util.Date;

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

public class AutomatedDataDelegate implements JavaDelegate {

  @Override
  public void execute(DelegateExecution execution) throws Exception {
    Date now = new Date();
    execution.setVariable("autoWelcomeTime", now);
    System.out.println("Faux call to backend for [" 
    + execution.getVariable("fullName") + "]");
  }

}

将脚本任务更改为指向AutomatedDataDelegate的服务任务。

文件：$mvnProject/src/main/resources/onboarding.bpmn20.xml

<?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/processdef">
  <process id="onboarding" name="Onboarding" isExecutable="true">
...
    <scriptTask id="automatedIntro" name="Generic and Automated Data Entry" scriptFormat="javascript" activiti:autoStoreVariables="false">
      <script><![CDATA[var dateAsString = new Date().toString();
execution.setVariable("autoWelcomeTime", dateAsString);]]></script>
    </scriptTask>
...

替换为：

<?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/processdef">
  <process id="onboarding" name="Onboarding" isExecutable="true">
...
   <serviceTask id="automatedIntro" name="Generic and Automated Data Entry" activiti:class="com.example.AutomatedDataDelegate"></serviceTask>

通过运行“mvn package”来打包代码。

像以前一样运行Java程序，注意以下示例输出。

ProcessEngine [default] Version: [5.22.0.0]
Found process definition [Onboarding] with id [onboarding:1:4]
Onboarding process started with process instance id [5] key [onboarding]
Active outstanding tasks: [1]
Processing Task [Enter Data]
Full Name?
John Doe
Years of Experience? (Must be a whole number)
3
Faux call to backend for [John Doe]
BEGIN Onboarding [onboarding] Sun Nov 27 22:57:32 EST 2016
-- Start [startOnboarding] 4 ms
-- Enter Data [enterOnboardingData] 10153 ms
-- Years of Experience [decision] 2 ms
-- Generic and Automated Data Entry [automatedIntro] 0 ms
-- End [endOnboarding] 0 ms
COMPLETE Onboarding [onboarding] Sun Nov 27 22:57:42 EST 2016

观察输出“Faux call to backend for [John Doe]”，该图说明了如何访问先前设置的流程变量。

这个简单的示例说明了在应用程序中添加流程驱动的抽象的简便性和强大功能。

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