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>