import org.springframework.binding.convert.service.DefaultConversionService; //导入依赖的package包/类
/**
 * Creates the {@link FlowBuilderServices} and configures it as follows:
 * 
 * * Set the WebFlow {@link org.springframework.binding.convert.ConversionService} 
 *   that delegates on the default Spring MVC {@link ConversionService}.
 * * Set the default Spring MVC {@link Validator} as the default Spring WebFlow Validator.
 * * Register the {@link StringToNullConverter}.
 * * Enable/disable flow and views cache (cache enabled by default).
 * * View factories creator that resolve their views by loading flow-relative resources.
 * 
 * @return the FlowBuilderServices
 */
@Bean
public FlowBuilderServices flowBuilderServices() {

  DefaultConversionService webFlowConversionService =
      new DefaultConversionService(this.conversionService);

  webFlowConversionService.addConverter(new StringToNullConverter());

  return getFlowBuilderServicesBuilder().setViewFactoryCreator(mvcViewFactoryCreator())
      .setConversionService(webFlowConversionService).setValidator(this.validator)
      .setDevelopmentMode(!this.development).build();
}