<mvc:annotation-driven/>相当于注册了DefaultAnnotationHandlerMapping和AnnotationMethodHandlerAdapter两个bean,配置一些messageconverter。即解决了@Controller注解的使用前提配置。
<context:annotation-config/>是对包进行扫描,实现注释驱动Bean定义,同时将bean自动注入容器中使用。即解决了@Controller标识的类的bean的注入和使用。
一开始我在写配置的时候,只写了<context:component-scan/>,并没有使用<mvc:annotation-driven/>,servlet拦截*.do,.do请求可以被正确捕捉和处理。代码如下
mvc-servlet.xml
<context:component-scan base-package="com"></context:component-scan>
web.xml
1. <servlet> 2. <servlet-name>mvc</servlet-name> 3. <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> 4. <load-on-startup>1</load-on-startup> 5. </servlet> 6. <servlet-mapping> 7. <servlet-name>mvc</servlet-name> 8. <url-pattern>*.do</url-pattern> 9. </servlet-mapping>
后来为了解决静态资源访问的问题,servlet改成了拦截所有请求,即/,并添加了默认的servlet,这时候*.do请求不能被控制器捕捉了,页面错误为404。直到添加了<mvc:annotation-driven/>之后,.do请求才又能被正确捕捉和处理。代码如下
mvc-servlet.xml
1. <context:component-scan base-package="com"></context:component-scan> 2. <mvc:annotation-driven/> 3. <mvc:resources mapping="/styles/**" location="/WEB-INF/resource/styles/"/> 4. <mvc:default-servlet-handler/>
web.xml
1. <servlet> 2. <servlet-name>mvc</servlet-name> 3. <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> 4. <load-on-startup>1</load-on-startup> 5. </servlet> 6. <servlet-mapping> 7. <servlet-name>mvc</servlet-name> 8. <url-pattern>/</url-pattern> 9. </servlet-mapping>
是什么原因造成这种区别的呢?为什么一开始没用<mvc:annotation-driven/>的时候可以,添加了默认servlet之后就不行了呢?
回答
最后的配置如果没有<mvc:annotation-driven/>,那么所有的Controller可能就没有解析,所有当有请求时候都没有匹配的处理请求类,就都去<mvc:default-servlet-handler/>即default servlet处理了。添加上<mvc:annotation-driven/>后,相应的do请求被Controller处理,而静态资源因为没有相应的Controller就会被default servlet处理。总之没有相应的Controller就会被default servlet处理就ok了。
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This tag registers the DefaultAnnotationHandlerMapping and AnnotationMethodHandlerAdapter beans that are required for Spring MVC to dispatch requests to Controllers.
这个标签注册了Spring MVC分发请求到控制器所必须的DefaultAnnotationHandlerMapping和AnnotationMethodHandlerAdapter实例
The tag configures those two beans with sensible defaults based on what is present in your classpath.
标签配置的这2个实例可以根据classpath中的内容默认提供以下功能:
The defaults are:
1. Support for Spring 3's Type ConversionService in addition to JavaBeans PropertyEditors during Data Binding.
A ConversionService instance produced by the org.springframework.format.support.FormattingConversionServiceFactoryBean is used by default.
This can be overriden by setting the conversion-service attribute.
支持spring3的javaBeans属性编辑器数据绑定时的类型转换服务。
类型转换服务实例默认为org.springframework.format.support.FormattingConversionServiceFactoryBean。
可以覆盖conversion-service属性来指定类型转换服务实例类。
2. Support for formatting Number fields using the @NumberFormat annotation
支持@NumberFormat 注解格式化数字类型字段。
3. Support for formatting Date, Calendar, Long, and Joda Time fields using the @DateTimeFormat annotation, if Joda Time 1.3 or higher is present on the classpath.
@DateTimeFormat注解格式化 Date, Calendar, Long和 Joda Time(如classpath下存在Joda Time 1.3或更高版本)字段
4. Support for validating @Controller inputs with @Valid, if a JSR-303 Provider is present on the classpath.
The validation system can be explicitly configured by setting the validator attribute.
支持@Valid注解验证控制器数据,classpath中需JSR-303的**。
可以使用setting明确的配置
5. Support for reading and writing XML, if JAXB is present on the classpath.
支持读写xml,classpath中需JAXB 。
6. Support for reading and writing JSON, if Jackson is present on the classpath.
支持读写json,classpath中需Jackson 。
A typical usage is shown below:
下边是用法:
<?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-3.0.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">
<!-- JSR-303 support will be detected on classpath and enabled automatically -->
<mvc:annotation-driven/>
</beans>
求上述1-6的使用例子。
总结:
要使用spring mvc中的@Controller注解,就必须要配置<mvc:annotation-driven />,否则org.springframework.web.servlet.DispatcherServlet无法找到控制器并把请求分发到控制器。
转自:http://www.iteye.com/problems/66133
http://www.noday.net/articles/2011/08/27/1314458126911.html
http://blog.csdn.net/jbgtwang/article/details/7359592