springmvc(1)--配置

最近把spring的使用整理下，版本4.1.1.RELEASE

SpringMVC是一个基于DispatcherServlet的MVC框架，每一个请求先访问的都是DispatcherServlet，DispatcherServlet负责转发每一个Request请求给相应的Handler，Handler处理以后再返回相应的视图(View)和模型(Model)，返回的视图和模型都可以不指定，即可以只返回Model或只返回View或都不返回。

<!--spring-mvc入口-->
    <servlet>
        <servlet-name>appServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:servlet-context.xml</param-value>
        </init-param>
        <load-on-startup>0</load-on-startup>
    </servlet>

servlet-context.xml内容如下：

<?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:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

    <!--处理静态资源-->
    <mvc:resources mapping="/resources/**" location="/resources/"/>

    <!--注解类所在jar包-->
    <context:component-scan base-package="springtry.web.controller">
        <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Service"/>
    </context:component-scan>

    <!--启动注解处理(@Controller等)-->
    <mvc:annotation-driven
            content-negotiation-manager="contentNegotiationManager"
            conversion-service="conversionService"/>
    <bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping" />
    <!-- 处理请求和注解POJO的映射 -->
    <bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter">
        <property name="messageConverters">
            <list>
                <ref bean="mappingJacksonHttpMessageConverter" /><!--json转换器-->
            </list>
        </property>
    </bean>
    <bean id="mappingJacksonHttpMessageConverter"
          class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
        <property name="supportedMediaTypes"><!--request/response的Content-Typ-->
            <list>
                <value>text/html;charset=UTF-8</value><!-- 避免IE执行AJAX时,返回JSON出现下载文件 -->
                <value>application/json;charset=UTF-8</value>
            </list>
        </property>
    </bean>

    <bean id="conversionService"
          class="org.springframework.format.support.FormattingConversionServiceFactoryBean">
        <property name="converters">
            <set>
                <!-- <bean class="***" /> -->
            </set>
        </property>
    </bean>

    <!--视图协商管理器-->
    <bean id="contentNegotiationManager"
          class="org.springframework.web.accept.ContentNegotiationManager">
        <constructor-arg>
            <bean class="org.springframework.web.accept.PathExtensionContentNegotiationStrategy">
                <constructor-arg>
                    <map>
                        <entry key="json" value="application/json;charset=utf-8"/>
                        <entry key="xml" value="application/xml;charset=utf-8"/>
                    </map>
                </constructor-arg>
            </bean>
        </constructor-arg>
    </bean>

    <bean id="velocityConfigurer"
          class="org.springframework.web.servlet.view.velocity.VelocityConfigurer">
        <property name="resourceLoaderPath" value="/WEB-INF/vm/"/>
        <property name="velocityProperties">
            <props>
                <prop key="directive.foreach.counter.name">loopCounter</prop>
                <prop key="directive.foreach.counter.initial.value">0</prop>
                <prop key="input.encoding">UTF-8</prop>
                <prop key="output.encoding">UTF-8</prop>
                <prop key="directive.foreach.counter.name">velocityCount</prop>
                <prop key="directive.foreach.counter.initial.value">1</prop>
                <prop key="velocimacro.library.autoreload">true</prop>
            </props>
        </property>
    </bean>

    <!--支持在Spring MVC下输出不同的格式-->
    <bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
        <property name="order" value="1"/>
        <property name="contentNegotiationManager" ref="contentNegotiationManager"/>
        <property name="viewResolvers">
            <list>
                <bean class="org.springframework.web.servlet.view.BeanNameViewResolver"/>
                <bean class="org.springframework.web.servlet.view.velocity.VelocityViewResolver">
                    <property name="order" value="0"/>
                    <property name="cache" value="true"/>
                    <property name="prefix" value=""/>
                    <property name="suffix" value=".vm"/>
                    <property name="toolboxConfigLocation" value="/WEB-INF/toolbox.xml"/>
                    <property name="contentType" value="text/html;charset=UTF-8"/>
                    <property name="viewClass" value="springtry.web.util.VelocityToolbox2View"></property>
                    <!--<property name="attributesMap">
                        <map>
                            <entry key="sec">
                                <ref bean="velocitySecurityUtil"/>
                            </entry>
                            <entry key="req">
                                <ref bean="requestUtil"/>
                            </entry>
                        </map>
                    </property>-->
                </bean>
                <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
                    <property name="prefix" value="/WEB-INF/views/"/>
                    <property name="suffix" value=".jsp"/>
                </bean>
            </list>
        </property>
        <property name="defaultViews">
            <list>
                <bean id="jsonView"
                      class="org.springframework.web.servlet.view.json.MappingJackson2JsonView"/>
            </list>
        </property>
    </bean>

    <bean id="exceptionResolver"
          class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
        <property name="defaultErrorView" value="errors/error"/>
        <property name="exceptionMappings">
            <props>
                <prop key="java.lang.Throwable">errors/error</prop>
            </props>
        </property>
    </bean>

</beans>

详解：

1.<mvc:annotation-driven />标签,使用了比较重要的两个bean

<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping" />

<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter">

 解析类是org.springframework.web.servlet.config.AnnotationDrivenBeanDefinitionParser,通过使用

RootBeanDefinition handlerMappingDef = new RootBeanDefinition(RequestMappingHandlerMapping.class);
处理@RequestMapping,并将其注册到请求映射表中

通过使用
RootBeanDefinition handlerAdapterDef = new RootBeanDefinition(RequestMappingHandlerAdapter.class);
...
this.addResponseBodyAdvice(handlerAdapterDef);
处理@Controller,确定调用哪个controller的哪个方法来处理当前请求

ps:网上说这个标签等同于单独定义这两个bean，我有异议，推荐同时使用，可以个性化定制RequestMappingHandlerMapping和RequestMappingHandlerAdapter

2.conversion-service="conversionService",上面的配置中使用了这项，什么意思呢？

提交到后台的数据通常都是字符串类型的，需要进行类型转换，这就是conversionService的作用了，发现一个问题，这个不是和RequestMappingHandlerAdapter定义的messageConverters冲突了么？没关系，因为messageConverters只针对requestBody(@RequestBody)

后面再详细介绍conversionService的各种类型转换

3.<bean id="contentNegotiationManager" class="org.springframework.web.accept.ContentNegotiationManager"/>

 以什么MediaTypes相应请求

4.<bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">

协商视图解析器