Spring MVC 中，<mvc:annotation-driven /> 标签的注意点

最新推荐文章于 2024-02-01 22:43:23 发布

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#spring #mvc #mvc-annota #converter

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从Spring Framework 3.1开始，<mvc:annotation-driven/>注册了新的支持类，如RequestMappingHandlerMapping、RequestMappingHandlerAdapter等，取代了早期的DefaultAnnotationHandlerMapping和AnnotationMethodHandlerAdapter等。这些类支持注解控制器的请求处理，并启用了更多特性。

<mvc:annotation-driven /> 是一种简写形式，完全可以手动配置替代这种简写形式，简写形式可以让初学都快速应用默认配置方案。

<mvc:annotation-driven /> 会自动注册 DefaultAnnotationHandlerMapping 与 AnnotationMethodHandlerAdapter 这两个bean, 它们是 Spring MVC 为 @Controller 分发请求所必须的。

这段话我在很多帖子都看到过，我自己的项目本身使用的Spring MVC 4.3.5，实际上在3.1之后，<mvc:annotation-driven />注册的类是发生了变化的。

下面是官方文档里的说明：

Spring Framework 3.1 introduces a new set of support classes for processing requests with annotated controllers:

RequestMappingHandlerMapping
RequestMappingHandlerAdapter
ExceptionHandlerExceptionResolver

These classes are a replacement for the existing:

DefaultAnnotationHandlerMapping
AnnotationMethodHandlerAdapter
AnnotationMethodHandlerExceptionResolver

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <mvc:annotation-driven />

</beans>

The above registers a RequestMappingHandlerMapping, a RequestMappingHandlerAdapter, and an ExceptionHandlerExceptionResolver (among others) in support of processing requests with annotated controller methods using annotations such as @RequestMapping , @ExceptionHandler, and others.

It also enables the following:

Spring 3 style type conversion through a ConversionService instance in addition to the JavaBeans PropertyEditors used for Data Binding.
Support for formatting Number fields using the @NumberFormat annotation through the ConversionService.
Support for formatting Date, Calendar, Long, and Joda Time fields using the @DateTimeFormat annotation.
Support for validating @Controller inputs with @Valid, if a JSR-303 Provider is present on the classpath.
HttpMessageConverter support for @RequestBody method parameters and @ResponseBody method return values from @RequestMapping or @ExceptionHandler methods.

This is the complete list of HttpMessageConverters set up by mvc:annotation-driven:

ByteArrayHttpMessageConverter converts byte arrays.
StringHttpMessageConverter converts strings.
ResourceHttpMessageConverter converts to/from org.springframework.core.io.Resource for all media types.
SourceHttpMessageConverter converts to/from a javax.xml.transform.Source.
FormHttpMessageConverter converts form data to/from a MultiValueMap<String, String>.
Jaxb2RootElementHttpMessageConverter converts Java objects to/from XML — added if JAXB2 is present on the classpath.
MappingJackson2HttpMessageConverter (or MappingJacksonHttpMessageConverter) converts to/from JSON — added if Jackson 2 (or Jackson) is present on the classpath.
AtomFeedHttpMessageConverter converts Atom feeds — added if Rome is present on the classpath.
RssChannelHttpMessageConverter converts RSS feeds — added if Rome is present on the classpath.