如何理解SpringMVC

<!-- 加入变量，替代我们用到的工程版本 -->
 <properties>
 	<commons-lang-version>2.6</commons-lang-version>
 	<slf4j-version>1.7.6</slf4j-version>
 	<spring-version>4.1.3.RELEASE</spring-version>
 </properties>
 
 <!-- 配置依赖管理：让maven帮我们管理传递依赖 -->
 <dependencyManagement>
 	<dependencies>
 		<dependency>
 			<groupId>org.springframework</groupId>
 			<artifactId>spring-framework-bom</artifactId>
 			<version>${spring.version}</version>
 			<scope>import</scope>
 		</dependency>
 	</dependencies>
 </dependencyManagement>
 
 <!-- 配置这个项目所依赖的包 -->
 <dependencies>
   <dependency>
     <groupId>junit</groupId>
     <artifactId>junit</artifactId>
     <version>3.8.1</version>
     <scope>test</scope>
   </dependency>
   
   <dependency>
   	<groupId>org.springframework</groupId>
   	<artifactId>spring-webmvc</artifactId>
   	<version>4.1.3.RELEASE</version>
   </dependency>
   
   <dependency>
   	<groupId>commons-lang</groupId>
   	<artifactId>commons-lang</artifactId>
   	<version>2.6</version>
   </dependency>
   
   <dependency>
   	<groupId>org.slf4j</groupId>
   	<artifactId>slf4j-log4j12</artifactId>
   	<version>1.7.6</version>
   	<exclusions>
   		<exclusion>
   			<groupId>org.slf4j</groupId>
   			<artifactId>slf4j-api</artifactId>
   		</exclusion>
   	</exclusions>
   </dependency>
   
 </dependencies>
 
 <!-- 添加组件：jetty是为了方便测试运行 -->
 <build>
 	<plugins>
 		<plugin>
 			<groupId>org.eclipse.jetty</groupId>
 			<artifactId>jetty-maven-plugin</artifactId>
 			<version>9.2.2.v20140723</version>
 		</plugin>
 	</plugins>
 </build>

<?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"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
    http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">
    
    <!-- 激活@Required @Autowired @Resource等标注 -->
    <context:annotation-config/>
    
    <!-- DispatcherServlet上下文，只搜索@Controller标注的类，不搜索其他标注的类 -->
    <context:component-scan base-package="com.ztl.springmvc.controller">
    	<context:include-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
    </context:component-scan>
    <!-- 让DispatcherServlet启用基于Annotation的HandlerMapping -->
    <mvc:annotation-driven/>
    
    <!-- 将静态文件指定到某个特殊的文件夹中统一处理 -->
    <mvc:resources location="/resources/" mapping="/resources/**"/>
    
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    	<property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
    	<property name="prefix" value="/WEB-INF/jsp/"/>
    	<property name="suffix" value=".jsp"/>
    </bean>
    
    <bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
    	<property name="exceptionMappings">
    		<props>
    			<prop key="com.ztl.springmvc.UserException">error</prop>
    			<prop key="java.lang.NullPointException">exception</prop>
    		</props>
    	</property>
    </bean>
</beans>

package com.ztl.springmvc.controller;
 
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
 
@Controller
@RequestMapping("/hello")
public class HelloMvcController {
	@RequestMapping("/sayhello")
	public String sayHello(){
		return "home";
	}	
}