Spring MVC之messageConverters

<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

1. <?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3. xmlns:mvc="http://www.springframework.org/schema/mvc"
4. xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
5. xsi:schemaLocation="
6. http://www.springframework.org/schema/beans
7. http://www.springframework.org/schema/beans/spring-beans.xsd
8. http://www.springframework.org/schema/mvc
9. http://www.springframework.org/schema/mvc/spring-mvc.xsd">
10. <mvc:annotation-driven />
11. </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.

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：

1. <mvc:annotation-driven conversion-service="conversionService">
2. <mvc:message-converters>
3. <bean class="org.example.MyHttpMessageConverter"/>
4. <bean class="org.example.MyOtherHttpMessageConverter"/>
5. </mvc:message-converters>
6. </mvc:annotation-driven>

下面展示我自己的配置

1. <?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3. xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"
4. xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
5. xmlns:jdbc="http://www.springframework.org/schema/jdbc" xmlns:mvc="http://www.springframework.org/schema/mvc"
6. xmlns:util="http://www.springframework.org/schema/util"
7. xsi:schemaLocation="http://www.springframework.org/schema/beans
8. http://www.springframework.org/schema/beans/spring-beans.xsd
9. http://www.springframework.org/schema/tx
10. http://www.springframework.org/schema/tx/spring-tx.xsd
11. http://www.springframework.org/schema/context
12. http://www.springframework.org/schema/context/spring-context.xsd
13. http://www.springframework.org/schema/aop
14. http://www.springframework.org/schema/aop/spring-aop.xsd
15. http://www.springframework.org/schema/jdbc
16. http://www.springframework.org/schema/jdbc/spring-jdbc-3.2.xsd
17. http://www.springframework.org/schema/util
18. http://www.springframework.org/schema/util/spring-util-3.2.xsd
19. http://www.springframework.org/schema/mvc
20. http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd">
21. <!-- spring自动扫描注解的组件 -->
22. <context:component-scan base-package="cn.xx.xx"
23. use-default-filters="false">
24. <context:include-filter expression="org.springframework.stereotype.Controller"
25. type="annotation" />
26. </context:component-scan>
27. <mvc:annotation-driven>
28. <mvc:message-converters>
29. <ref bean="stringHttpMessageConverter" />
30. <ref bean="fastJsonHttpMessageConverter" />
31. <ref bean="marshallingHttpMessageConverter" />
32. </mvc:message-converters>
33. </mvc:annotation-driven>
34. <bean id="stringHttpMessageConverter"
35. class="org.springframework.http.converter.StringHttpMessageConverter">
36. <constructor-arg value="UTF-8" index="0"></constructor-arg><!--
37. 避免出现乱码 -->
38. <property name="supportedMediaTypes">
39. <list>
40. <value>text/plain;charset=UTF-8</value>
41. </list>
42. </property>
43. </bean>
44. <bean id="fastJsonHttpMessageConverter"
45. class="com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter">
46. <property name="supportedMediaTypes">
47. <list>
48. <value>application/json;charset=UTF-8</value>
49. <value>text/html;charset=UTF-8</value><!-- 避免IE出现下载JSON文件的情况 -->
50. </list>
51. </property>
52. <property name="features">
53. <util:list>
54. <!-- <value>WriteMapNullValue</value> -->
55. <value>QuoteFieldNames</value>
56. <value>WriteDateUseDateFormat</value>
57. </util:list>
58. </property>
59. </bean>
60. <bean id="marshallingHttpMessageConverter"
61. class="org.springframework.http.converter.xml.MarshallingHttpMessageConverter">
62. <property name="marshaller" ref="castorMarshaller" />
63. <property name="unmarshaller" ref="castorMarshaller" />
64. <property name="supportedMediaTypes">
65. <list>
66. <value>text/xml;charset=UTF-8</value>
67. <value>application/xml;charset=UTF-8</value>
68. </list>
69. </property>
70. </bean>
71. <!-- 返回类型定义 -->
72. <util:list id="messageConverters">
73. <ref bean="stringHttpMessageConverter" />
74. <ref bean="fastJsonHttpMessageConverter" />
75. <ref bean="marshallingHttpMessageConverter" />
76. </util:list>
77. <bean id="castorMarshaller" class="org.springframework.oxm.castor.CastorMarshaller" />
78. <!-- AOP自动注解功能 -->
79. <aop:aspectj-autoproxy />
80. <!-- 不进行拦截的 -->
81. <mvc:resources location="/" mapping="/**/*.html" order="0" />
82. <mvc:resources location="/images/" mapping="/images/**" />
83. <mvc:resources location="/img/" mapping="/img/**" />
84. <mvc:resources location="/download/" mapping="/download/**" />
85. <mvc:resources location="/js/" mapping="/js/**" />
86. <mvc:resources location="/css/" mapping="/css/**" />
87. <mvc:resources location="/plugin/" mapping="/plugin/**" />
88. <mvc:resources location="/WEB-INF/pages/" mapping="/pages/**" />
89. <bean id="messageSource"
90. class="org.springframework.context.support.ResourceBundleMessageSource">
91. <property name="basename" value="messages"></property>
92. </bean>
93. <bean
94. class="org.springframework.web.servlet.view.InternalResourceViewResolver">
95. <property name="prefix" value="/WEB-INF/pages/" />
96. <property name="suffix" value=".jsp" />
97. </bean>
98. <!-- 支持上传文件 -->
99. <bean id="multipartResolver"
100. class="org.springframework.web.multipart.commons.CommonsMultipartResolver" />
101. <!-- restTemplate -->
102. <bean id="restTemplate" class="org.springframework.web.client.RestTemplate">
103. <property name="messageConverters" ref="messageConverters">
104. </property>
105. </bean>
106. </beans>