springmvc之DispatcherServlet

1、作用:DispatcherServlet是前置控制器,配置在web.xml(因为DispatcherServlet是一个servelet)文件中的。拦截匹配的请求,Servlet拦截匹配规则要自已定义(<servlet-mapping>的<url-pattern>中配置),把拦截下来的请求依据相应的规则分发到目标Controller来处理,是配置spring MVC的第一步。

2、web.xml中的配置

   <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

1)DispatcherServlet的配置就是servlet的配置,<servlet-name>、<servlet-class>、<load-on-startup>分别代表servlet名称、类路径、加载次序,<servlet-mapping>中的<url-pattern>配置拦截匹配规则。

2)springmvc是servlet的名字,多个DispatcherServlet通过名字来区别,每一个DispatcherServlet有自己的WebApplicationContext上下文对象,在DispatcherServlet的初始化过程中,框架会在web应用的 WEB-INF文件夹下寻找名为[servlet-name]-servlet.xml (本文的上下文文件名为springmvc-servlet.xml)的配置文件,生成文件中定义的bean。

3)WebApplicationContext上下文文件的配置可以有多种方法,需要配置<init-param>参数

  a、不写,使用默认值:/WEB-INF/[servlet-name]-servlet.xml
  b、<param-value>/WEB-INF/classes/springMVC.xml</param-value>
  c、<param-value>classpath*:springMVC-mvc.xml</param-value>
  注:多个值用逗号分隔

如下:

<servlet>
        <servlet-name>springmvc1</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/springmvc-servlet.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>springmvc1</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

3、上面用到的上下问文件如下

<?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:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:p="http://www.springframework.org/schema/p"
       xsi:schemaLocation="
    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
    http://www.springframework.org/schema/mvc
    http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">

    <context:component-scan base-package="com.controller"/>

    <mvc:annotation-driven/>

    <bean id="viewResolver"
          class="org.springframework.web.servlet.view.UrlBasedViewResolver">
        <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
        <property name="prefix" value="/WEB-INF/views/"/>
        <property name="suffix" value=".jsp"/>
        <property name="redirectHttp10Compatible" value="false" />
    </bean>

</beans>

 

posted @ 2016-09-12 14:27  code.world  Views(284)  Comments(0Edit  收藏  举报