flowable ProcessEngine和ProcessEngineConfiguration

本文主要是介绍flowable ProcessEngine和ProcessEngineConfiguration，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

ProcessEngine是流程引擎，ProcessEngineConfiguration与前面四个引擎配置有些不同。

ProcessEngineConfiguration增加了邮件服务和httpClient的封装。

一、实例化

ProcessEngineConfiguration 提供了7个公共的静态方法用于实例化。

   public static ProcessEngineConfiguration createStandaloneProcessEngineConfiguration() {return new StandaloneProcessEngineConfiguration();}public static ProcessEngineConfiguration createStandaloneInMemProcessEngineConfiguration() {return new StandaloneInMemProcessEngineConfiguration();}

二、创建ProcessEngine

创建ProcessEngine的方法是在ProcessEngineConfiguration的子类 ProcessEngineConfigurationImpl中提供的。

@Overridepublic ProcessEngine buildProcessEngine() {init();ProcessEngineImpl processEngine = new ProcessEngineImpl(this);
...return processEngine;}

三、初始化服务

创建引擎过程调用init()方法时，初始化服务。

public void init() {
...
initServices();
...
}public void initServices() {initService(repositoryService);initService(runtimeService);initService(historyService);initService(identityService);initService(taskService);initService(formService);initService(managementService);initService(dynamicBpmnService);}public void initService(Object service) {if (service instanceof ServiceImpl) {((ServiceImpl) service).setCommandExecutor(commandExecutor);}}

这些服务定义在 ProcessEngineConfigurationImpl 中：

  protected RepositoryService repositoryService = new RepositoryServiceImpl();protected RuntimeService runtimeService = new RuntimeServiceImpl();protected HistoryService historyService = new HistoryServiceImpl(this);protected IdentityService identityService = new IdentityServiceImpl(this);protected TaskService taskService = new TaskServiceImpl(this);protected FormService formService = new FormServiceImpl();protected ManagementService managementService = new ManagementServiceImpl();protected DynamicBpmnService dynamicBpmnService = new DynamicBpmnServiceImpl(this);