activiti:initiator详解

SubmitStartFormCmd的excute方法：
 
  protected ProcessInstance execute(CommandContext commandContext, ProcessDefinitionEntity processDefinition) {
     ExecutionEntity processInstance = null;
     if (businessKey != null) {
       processInstance = processDefinition.createProcessInstance(businessKey);
     } else {
       processInstance = processDefinition.createProcessInstance();
     }
 
     commandContext.getHistoryManager()
       .reportFormPropertiesSubmitted(processInstance, properties, null);
 
     StartFormHandler startFormHandler = processDefinition.getStartFormHandler();
     startFormHandler.submitFormProperties(properties, processInstance);
 
 
     processInstance.start();
 
     return processInstance;
   }
 

  public ExecutionEntity createProcessInstance(String businessKey, ActivityImpl initial) {
     ExecutionEntity processInstance = null;
 
     if(initial == null) {
       processInstance = (ExecutionEntity) super.createProcessInstance();
     }else {
       processInstance = (ExecutionEntity) super.createProcessInstanceForInitial(initial);
     }
 
 
     processInstance.setExecutions(new ArrayList<ExecutionEntity>());
     processInstance.setProcessDefinition(processDefinition);
     // Do not initialize variable map (let it happen lazily)
 
 
     // Set business key (if any)
     if (businessKey != null) {
 processInstance.setBusinessKey(businessKey);
     }
 
     // Inherit tenant id (if any)
     if (getTenantId() != null) {
 processInstance.setTenantId(getTenantId());
     }
 
     // Reset the process instance in order to have the db-generated process instance id available
     processInstance.setProcessInstance(processInstance);
 
     // initialize the template-defined data objects as variables first
     Map<String, Object> dataObjectVars = getVariables();
     if (dataObjectVars != null) {
       processInstance.setVariables(dataObjectVars);
     }
 
     String authenticatedUserId = Authentication.getAuthenticatedUserId();
     String initiatorVariableName = (String) getProperty(BpmnParse.PROPERTYNAME_INITIATOR_VARIABLE_NAME);
     if (initiatorVariableName!=null) {
 processInstance.setVariable(initiatorVariableName, authenticatedUserId);
     }
     if (authenticatedUserId != null) {
       processInstance.addIdentityLink(authenticatedUserId, null, IdentityLinkType.STARTER);
     }
 
     Context.getCommandContext().getHistoryManager()
       .recordProcessInstanceStart(processInstance);
 
     if (Context.getProcessEngineConfiguration().getEventDispatcher().isEnabled()) {
         Context.getProcessEngineConfiguration().getEventDispatcher().dispatchEvent(
                 ActivitiEventBuilder.createEntityEvent(ActivitiEventType.ENTITY_CREATED, processInstance));
     }
 
     return processInstance;
   }