Spring MVC之messageConverters

<mvc:annotation-driven /> 是一種簡寫形式，徹底能夠手動配置替代這種簡寫形式，簡寫形式可讓初學都快速應用默認配置方案。<mvc:annotation-driven /> 會自動註冊DefaultAnnotationHandlerMapping與AnnotationMethodHandlerAdapter 兩個bean,是spring MVC爲@Controllers分發請求所必須的。

這句話我在不少帖子都看到過，我本身的項目自己使用的Spring MVC 3.2，實際上在3.1以後，<mvc:annotation-driven />註冊的類發生了變化

 

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

<?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:

1. Spring 3 style type conversion through a ConversionService instance in addition to the JavaBeans PropertyEditors used for Data Binding.

2. Support for formatting Number fields using the @NumberFormat annotation through the ConversionService.

3. Support for formatting Date, Calendar, Long, and Joda Time fields using the @DateTimeFormat annotation.

4. Support for validating @Controller inputs with @Valid, if a JSR-303 Provider is present on the classpath.

5. 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.

這是摘取的官方文檔，能夠看出，註冊的類已經變成了RequestMappingHandlerMapping和 RequestMappingHandlerAdapter。

我以前在不知道的時候，使用AnnotationMethodHandlerAdapter 進行配置，結果在有<mvc:annotation-driven />存在的狀況下，我本身配置的AnnotationMethodHandlerAdapter 怎麼都不起做用，因而去掉了<mvc:annotation-driven />標籤，手動註冊了AnnotationMethodHandlerAdapter ，和DefaultAnnotationHandlerMapping。結果引起了其餘問題，好比文件沒法上傳的問題。

 

閱讀文檔發現Spring提供了基於<mvc:annotation-driven />自定義messageConverters的方法，以下所示：

 

<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>

 

下面展現我本身的配置

 

<?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">

    <!-- spring自動掃描註解的組件 -->
    <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><!--
            避免出現亂碼 -->
        <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><!-- 避免IE出現下載JSON文件的狀況 -->
            </list>
        </property>
        <property name="features">
            <util:list>
                <!-- <value>WriteMapNullValue</value> -->
                <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>

    <!-- 返回類型定義 -->
    <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自動註解功能 -->
    <aop:aspectj-autoproxy />

    <!-- 不進行攔截的 -->
    <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>

    <!-- 支持上傳文件 -->
    <bean id="multipartResolver"
        class="org.springframework.web.multipart.commons.CommonsMultipartResolver" />

    <!-- restTemplate -->
    <bean id="restTemplate" class="org.springframework.web.client.RestTemplate">
        <property name="messageConverters" ref="messageConverters">
        </property>
    </bean>
</beans>