一個使用示例，五個操作步驟！從此輕鬆掌握專案中工作流的開發

建立流程

要想操作Activiti引擎,需要透過org.activiti.engine.ProcessEngine例項暴露的服務.就可以操作一個org.activiti.engine.ProcessEngine
建立一個請假申請的工作業務流程:
釋出流程
任何與“靜態”資源有關的資料(比如流程定義)都可以透過RepositoryService訪問,從概念上講,所有靜態資料都是Activiti的資源內容

在src/test/resources/org/activiti/test目錄下建立一個新的xml檔案 VacationRequest.bpmn20.xml:

<?xml version="1.0" encoding="UTF-8" ?>
<definitions id="definitions"
           targetNamespace="http://activiti.org/bpmn20"
           xmlns="http://www.omg.org/spec/BPMN/20100524/MODEL"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xmlns:activiti="http://activiti.org/bpmn">

<process id="vacationRequest" name="Vacation request">

  <startEvent id="request" activiti:initiator="employeeName">
    <extensionElements>
      <activiti:formProperty id="numberOfDays" name="Number of days" type="long" value="1" required="true"/>
      <activiti:formProperty id="startDate" name="First day of holiday (dd-MM-yyy)" datePattern="dd-MM-yyyy hh:mm" type="date" required="true" />
      <activiti:formProperty id="vacationMotivation" name="Motivation" type="string" />
    </extensionElements>
  </startEvent>
  <sequenceFlow id="flow1" sourceRef="request" targetRef="handleRequest" />

  <userTask id="handleRequest" name="Handle vacation request" >
    <documentation>
      ${employeeName} would like to take ${numberOfDays} day(s) of vacation (Motivation: ${vacationMotivation}).
    </documentation>
    <extensionElements>
       <activiti:formProperty id="vacationApproved" name="Do you approve this vacation" type="enum" required="true">
        <activiti:value id="true" name="Approve" />
        <activiti:value id="false" name="Reject" />
      </activiti:formProperty>
      <activiti:formProperty id="managerMotivation" name="Motivation" type="string" />
    </extensionElements>
    <potentialOwner>
      <resourceAssignmentExpression>
        <formalExpression>management</formalExpression>
      </resourceAssignmentExpression>
    </potentialOwner>
  </userTask>
  <sequenceFlow id="flow2" sourceRef="handleRequest" targetRef="requestApprovedDecision" />

  <exclusiveGateway id="requestApprovedDecision" name="Request approved?" />
  <sequenceFlow id="flow3" sourceRef="requestApprovedDecision" targetRef="sendApprovalMail">
    <conditionExpression xsi:type="tFormalExpression">${vacationApproved == 'true'}</conditionExpression>
  </sequenceFlow>

  <task id="sendApprovalMail" name="Send confirmation e-mail" />
  <sequenceFlow id="flow4" sourceRef="sendApprovalMail" targetRef="theEnd1" />
  <endEvent id="theEnd1" />

  <sequenceFlow id="flow5" sourceRef="requestApprovedDecision" targetRef="adjustVacationRequestTask">
    <conditionExpression xsi:type="tFormalExpression">${vacationApproved == 'false'}</conditionExpression>
  </sequenceFlow>

  <userTask id="adjustVacationRequestTask" name="Adjust vacation request">
    <documentation>
      Your manager has disapproved your vacation request for ${numberOfDays} days.
      Reason: ${managerMotivation}
    </documentation>
    <extensionElements>
      <activiti:formProperty id="numberOfDays" name="Number of days" value="${numberOfDays}" type="long" required="true"/>
      <activiti:formProperty id="startDate" name="First day of holiday (dd-MM-yyy)" value="${startDate}" datePattern="dd-MM-yyyy hh:mm" type="date" required="true" />
      <activiti:formProperty id="vacationMotivation" name="Motivation" value="${vacationMotivation}" type="string" />
      <activiti:formProperty id="resendRequest" name="Resend vacation request to manager?" type="enum" required="true">
        <activiti:value id="true" name="Yes" />
        <activiti:value id="false" name="No" />
      </activiti:formProperty>
    </extensionElements>
    <humanPerformer>
      <resourceAssignmentExpression>
        <formalExpression>${employeeName}</formalExpression>
      </resourceAssignmentExpression>
    </humanPerformer>
  </userTask>
  <sequenceFlow id="flow6" sourceRef="adjustVacationRequestTask" targetRef="resendRequestDecision" />

  <exclusiveGateway id="resendRequestDecision" name="Resend request?" />
  <sequenceFlow id="flow7" sourceRef="resendRequestDecision" targetRef="handleRequest">
    <conditionExpression xsi:type="tFormalExpression">${resendRequest == 'true'}</conditionExpression>
  </sequenceFlow>

   <sequenceFlow id="flow8" sourceRef="resendRequestDecision" targetRef="theEnd2">
    <conditionExpression xsi:type="tFormalExpression">${resendRequest == 'false'}</conditionExpression>
  </sequenceFlow>
  <endEvent id="theEnd2" />

</process>

</definitions>

為了讓Activiti引擎知道這個流程,我們必須先進行[釋出],釋出意味著引擎會把BPMN 2.0 xml解析成可以執行的東西,釋出包中的所有流程定義都會新增到資料庫中.這樣,當引擎重啟時,它依然可以獲得[已釋出]的流程:

ProcessEngine processEngine = ProcessEngines.getDefaultProcessEngine();
RepositoryService repositoryService = processEngine.getRepositoryService();
repositoryService.createDeployment()
.addClasspathResource("org/activiti/test/VacationRequest.bpmn20.xml")
.deploy();

Log.info("Number of process definitions: " + repositoryService.createProcessDefinitionQuery().count());

啟動一個流程例項

把流程定義釋出到Activiti引擎後,可以基於它發起新流程例項.
對每個流程定義,都可以有很多流程例項.流程定義是"藍圖",流程例項是它的一個執行的執行

所有與流程執行狀態相關的東西都可以透過RuntimeService獲得.有很多方法可以啟動一個新流程例項.

可以在流程例項啟動時新增一些流程變數, 因為第一個使用者任務的表示式需要這些變數.流程變數經常會被用到,因為它們賦予來自同一個流程定義的不同流程例項的特別含義
流程變數是區分流程例項的關鍵

下面使用定義在流程定義xml 中的key來啟動流程例項:

Map<String, Object> variables = new HashMap<String, Object>();
variables.put("employeeName", "Kermit");
variables.put("numberOfDays", new Integer(4));
variables.put("vacationMotivation", "I'm really tired!");

RuntimeService runtimeService = processEngine.getRuntimeService();
ProcessInstance processInstance = runtimeService.startProcessInstanceByKey("vacationRequest", variables);

// Verify that we started a new process instance
Log.info("Number of process instances: " + runtimeService.createProcessInstanceQuery().count());

完成任務

流程啟動後,第一步就是使用者任務.這是必須由系統使用者處理的一個環節.

使用者會有一個"任務列表",展示了所有必須由整個使用者處理的任務.下面是對應的查詢:

// Fetch all tasks for the management group
TaskService taskService = processEngine.getTaskService();
List<Task> tasks = taskService.createTaskQuery().taskCandidateGroup("management").list();
for (Task task : tasks) {
Log.info("Task available: " + task.getName());
}

為了讓流程例項繼續執行,我們需要完成整個任務.對Activiti來說,就是需要complete任務:

Task task = tasks.get(0);

Map<String, Object> taskVariables = new HashMap<String, Object>();
taskVariables.put("vacationApproved", "false");
taskVariables.put("managerMotivation", "We have a tight deadline!");
taskService.complete(task.getId(), taskVariables);

然後流程例項就會進入到下一個環節
下一環節允許員工透過表單調整原始的請假申請.員工可以重新提交請假申請,這會使流程重新進入到第一個任務
掛起或啟用一個流程

可以掛起一個流程定義,當掛起流程定義時,就不能建立新流程了,會丟擲一個異常.可以透過RepositoryService掛起一個流程:

repositoryService.suspendProcessDefinitionByKey("vacationRequest");
try {
runtimeService.startProcessInstanceByKey("vacationRequest");
} catch (ActivitiException e) {
e.printStackTrace();
}

要想重新啟用一個流程定義,可以呼叫repositoryService.activateProcessDefinitionXXX方法
也可以掛起一個流程例項:
- 掛起時,流程不能繼續執行:比如,完成任務會丟擲異常,非同步操作(比如定時器)也不會執行.掛起流程例項可以呼叫runtimeService.suspendProcessInstance方法
- 啟用流程例項可以呼叫runtimeService.activateProcessInstanceXXX方法

一個使用示例，五個操作步驟！從此輕鬆掌握專案中工作流的開發

建立流程

釋出流程

啟動一個流程例項

完成任務

掛起或啟用一個流程

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