Spring MVC之messageConverters

浏览数：51 / 时间：2015年06月08日

<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 两个bean,是spring MVC为@Controllers分发请求所必须的。

这句话我在很多帖子都看到过，我自己的项目本身使用的Spring MVC 3.2，实际上在3.1之后，<mvc:annotation-driven />注册的类发生了变化

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

[html] view plain copy print ?

<?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.

这是摘取的官方文档，可以看出，注册的类已经变成了RequestMappingHandlerMapping和 RequestMappingHandlerAdapter。

我之前在不知道的时候，使用AnnotationMethodHandlerAdapter 进行配置，结果在有<mvc:annotation-driven />存在的情况下，我自己配置的AnnotationMethodHandlerAdapter 怎么都不起作用，于是去掉了<mvc:annotation-driven />标签，手动注册了AnnotationMethodHandlerAdapter ，和DefaultAnnotationHandlerMapping。结果引发了其他问题，比如文件无法上传的问题。

阅读文档发现Spring提供了基于<mvc:annotation-driven />自定义messageConverters的方法，如下所示：

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<mvc:annotation-driven conversion-service="conversionService">
<mvc:message-converters>
<bean class="org.example.MyHttpMessageConverter"/>
<bean class="org.example.MyOtherHttpMessageConverter"/>
</mvc:message-converters>
</mvc:annotation-driven>

下面展示我自己的配置

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<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:jdbc="http://www.springframework.org/schema/jdbc" xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:util="http://www.springframework.org/schema/util"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop.xsd
http://www.springframework.org/schema/jdbc
http://www.springframework.org/schema/jdbc/spring-jdbc-3.2.xsd
http://www.springframework.org/schema/util
http://www.springframework.org/schema/util/spring-util-3.2.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd">
<context:component-scan base-package="cn.xx.xx"
use-default-filters="false">
<context:include-filter expression="org.springframework.stereotype.Controller"
type="annotation" />
</context:component-scan>
<mvc:annotation-driven>
<mvc:message-converters>
<ref bean="stringHttpMessageConverter" />
<ref bean="fastJsonHttpMessageConverter" />
<ref bean="marshallingHttpMessageConverter" />
</mvc:message-converters>
</mvc:annotation-driven>
<bean id="stringHttpMessageConverter"
class="org.springframework.http.converter.StringHttpMessageConverter">
<constructor-arg value="UTF-8" index="0"></constructor-arg><!--
避免出现乱码 -->
<property name="supportedMediaTypes">
<list>
<value>text/plain;charset=UTF-8</value>
</list>
</property>
</bean>
<bean id="fastJsonHttpMessageConverter"
class="com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter">
<property name="supportedMediaTypes">
<list>
<value>application/json;charset=UTF-8</value>
<value>text/html;charset=UTF-8</value>
</list>
</property>
<property name="features">
<util:list>
<value>QuoteFieldNames</value>
<value>WriteDateUseDateFormat</value>
</util:list>
</property>
</bean>
<bean id="marshallingHttpMessageConverter"
class="org.springframework.http.converter.xml.MarshallingHttpMessageConverter">
<property name="marshaller" ref="castorMarshaller" />
<property name="unmarshaller" ref="castorMarshaller" />
<property name="supportedMediaTypes">
<list>
<value>text/xml;charset=UTF-8</value>
<value>application/xml;charset=UTF-8</value>
</list>
</property>
</bean>
<util:list id="messageConverters">
<ref bean="stringHttpMessageConverter" />
<ref bean="fastJsonHttpMessageConverter" />
<ref bean="marshallingHttpMessageConverter" />
</util:list>
<bean id="castorMarshaller" class="org.springframework.oxm.castor.CastorMarshaller" />
<aop:aspectj-autoproxy />
<mvc:resources location="/" mapping="/**/*.html" order="0" />
<mvc:resources location="/images/" mapping="/images/**" />
<mvc:resources location="/img/" mapping="/img/**" />
<mvc:resources location="/download/" mapping="/download/**" />
<mvc:resources location="/js/" mapping="/js/**" />
<mvc:resources location="/css/" mapping="/css/**" />
<mvc:resources location="/plugin/" mapping="/plugin/**" />
<mvc:resources location="/WEB-INF/pages/" mapping="/pages/**" />
<bean id="messageSource"
class="org.springframework.context.support.ResourceBundleMessageSource">
<property name="basename" value="messages"></property>
</bean>
<bean
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/pages/" />
<property name="suffix" value=".jsp" />
</bean>
<bean id="multipartResolver"
class="org.springframework.web.multipart.commons.CommonsMultipartResolver" />
<bean id="restTemplate" class="org.springframework.web.client.RestTemplate">
<property name="messageConverters" ref="messageConverters">
</property>
</bean>
</beans>