spring mvc前台时间字符串到后台Date的转换

无意中发现对于时间字符串转Date类，根本不用自己去写转换类，spring mvc已经实现了该功能，还是基于注解的，轻松省事，使用org.springframework.format.support.FormattingConversionServiceFactoryBean
之后，只要在vo里加注解就行了

	@DateTimeFormat(pattern="yyyy-MM-dd")
	private Date dateRangeStart;// 通行日期范围开始

@DateTimeFormat(pattern="yyyy-MM-dd") 可将形如1980-0-01的字符串转换到Date类
@NumberFormat(pattern="#,###.##") 可将形如4,500.00的字符串转换成long类型

怎么注册呢？

<bean id="conversionService"  
class="org.springframework.format.support.FormattingConversionServiceFactoryBean"> 
<mvc:annotation-driven validator="validator"  
    conversion-service="conversionService" />  

使用<mvc:annotation-driven /> 的话，默认就启用FormattingConversionServiceFactoryBean了，所以上面的配置也省了。
但是<mvc:annotation-driven />基本不用，因为总得做些个性化设置，那怎么注册FormattingConversionServiceFactoryBean给spring mvc呢？
起初我以为得从DefaultAnnotationHandlerMapping入手，后来通过看<mvc:annotation-driven />的解析器AnnotationDrivenBeanDefinitionParser源码，才发现原来是AnnotationMethodHandlerAdapter的属性

		RuntimeBeanReference conversionService = getConversionService(element, source, parserContext);
		RuntimeBeanReference validator = getValidator(element, source, parserContext);
		
		RootBeanDefinition bindingDef = new RootBeanDefinition(ConfigurableWebBindingInitializer.class);
		bindingDef.setSource(source);
		bindingDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
		bindingDef.getPropertyValues().add("conversionService", conversionService);
		bindingDef.getPropertyValues().add("validator", validator);

		RootBeanDefinition annAdapterDef = new RootBeanDefinition(AnnotationMethodHandlerAdapter.class);
		annAdapterDef.setSource(source);
		annAdapterDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
		annAdapterDef.getPropertyValues().add("webBindingInitializer", bindingDef);
		annAdapterDef.getPropertyValues().add("messageConverters", getMessageConverters(source));

getConversionService方法内部

		if (element.hasAttribute("conversion-service")) {
			return new RuntimeBeanReference(element.getAttribute("conversion-service"));
		}
		else {
			RootBeanDefinition conversionDef = new RootBeanDefinition(FormattingConversionServiceFactoryBean.class);
			conversionDef.setSource(source);
			conversionDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
			String conversionName = parserContext.getReaderContext().registerWithGeneratedName(conversionDef);
			parserContext.registerComponent(new BeanComponentDefinition(conversionDef, conversionName));
			return new RuntimeBeanReference(conversionName);
		}

原来<mvc:annotation-driven />是这么注册FormattingConversionServiceFactoryBean的
如果不使用<mvc:annotation-driven />标签的话,只要配置AnnotationMethodHandlerAdapter的属性就可以了

			<property name="webBindingInitializer">
				<bean class="org.springframework.web.bind.support.ConfigurableWebBindingInitializer">
					<property name="conversionService">
						<bean class="org.springframework.format.support.FormattingConversionServiceFactoryBean"></bean>
					</property>
				</bean>
			</property>