Camunda源码剖析之CamundaBpmAutoConfiguration(一)

# AutoConfigurations
org.springframework.boot.autoconfigure.EnableAutoConfiguration=org.camunda.bpm.spring.boot.starter.CamundaBpmAutoConfiguration

# Application Listeners
org.springframework.context.ApplicationListener=org.camunda.bpm.spring.boot.starter.runlistener.PropertiesListener

@EnableConfigurationProperties({
  // **********************************************************
  // 1. 启用配置类,与camunda相关的配置类都在这个类进行配置.
  // **********************************************************
  CamundaBpmProperties.class,
  ManagementProperties.class
})

// **********************************************************
// 2. 导入其它的配置类
// **********************************************************
@Import({
  // **********************************************************
  // 2.1 Camunda重要配置类
  // **********************************************************
  CamundaBpmConfiguration.class,
  // **********************************************************
  // 2.2 Actuator配置(不重要)
  // **********************************************************
  CamundaBpmActuatorConfiguration.class,
  // **********************************************************
  // 2.3 配置ProcessEnginePlugin的实现类
  // **********************************************************
  CamundaBpmPluginConfiguration.class,
  // **********************************************************
  // 2.4 获取Servlet容器的名称和版本,并把这个信息配置到:ManagementService里
  // **********************************************************
  CamundaBpmTelemetryConfiguration.class,
  // **********************************************************
  // 2.5 对ProcessEngineServices接口进行配置,实际:ProcessEngineServices就是一个门面类,Hold住了的有的其它Service(比如:RuntimeService/RepositoryService/FormService/TaskService/HistoryService/IdentityService/)
  //  典型的门面模式
  // **********************************************************
  SpringProcessEngineServicesConfiguration.class
})
@Configuration

// **********************************************************
// 3. camunda.bpm.enabled=true
// matchIfMissing: 缺少上面的配置(camunda.bpm.enabled),是否生效
// **********************************************************
@ConditionalOnProperty(prefix = CamundaBpmProperties.PREFIX, name = "enabled", matchIfMissing = true)
@AutoConfigureAfter(HibernateJpaAutoConfiguration.class)
public class CamundaBpmAutoConfiguration {
	// ... ... 
}

public class CamundaBpmAutoConfiguration {
	// BPMN版本管理
	@Bean
	public CamundaBpmVersion camundaBpmVersion() {
		return new CamundaBpmVersion();
	}
	
	// 监听:ApplicationReadyEvent/ContextClosedEvent事件,并重新发布成:
	// ProcessApplicationStartedEvent
	// ProcessApplicationStoppedEvent
	@Bean
	public ProcessApplicationEventPublisher processApplicationEventPublisher(ApplicationEventPublisher publisher) {
		return new ProcessApplicationEventPublisher(publisher);
	}
}

public class CamundaBpmAutoConfiguration {
  
  @Configuration
  class ProcessEngineConfigurationImplDependingConfiguration {
    
	
	// ******************************************************************
	// 1. 注入:ProcessEngineConfigurationImpl,先不管这个类是在哪初始化的,后面再剖析
	// ******************************************************************
    @Autowired
    protected ProcessEngineConfigurationImpl processEngineConfigurationImpl;

	
	// ******************************************************************
	// 2. 通过: ProcessEngineFactoryBean来创建:ProcessEngine实例
	//    注意:这个类比较重要,先把其它的类剖析完毕后,会另开一章去剖析这个类(ProcessEngineFactoryBean)
	// ******************************************************************
    @Bean
    public ProcessEngineFactoryBean processEngineFactoryBean() {
      final ProcessEngineFactoryBean factoryBean = new ProcessEngineFactoryBean();
      factoryBean.setProcessEngineConfiguration(processEngineConfigurationImpl);
      return factoryBean;
    }

	// ******************************************************************
	// 配置:CommandExecutor到Spring容器里.
	// ******************************************************************
    @Bean
    @Primary
    public CommandExecutor commandExecutorTxRequired() {
      return processEngineConfigurationImpl.getCommandExecutorTxRequired();
    }

    @Bean
    public CommandExecutor commandExecutorTxRequiresNew() {
      return processEngineConfigurationImpl.getCommandExecutorTxRequiresNew();
    }

    @Bean
    public CommandExecutor commandExecutorSchemaOperations() {
      return processEngineConfigurationImpl.getCommandExecutorSchemaOperations();
    }
  } // end ProcessEngineConfigurationImplDependingConfiguration
  
}