（1）在浏览器中访问，后台总报错：
no mapping found for http request with uri [/exam3/welcome] in dispatcherservlet with name 'spring2'
查了好半天，才发现是controller 没有扫描到。
我是使用的注解。
spring mvc配置文件如下：
<?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:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemalocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.2.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd"
>
<!-- handlermapping -->
<bean
class="org.springframework.web.servlet.handler.beannameurlhandlermapping" />
<!-- handleradapter -->
class="org.springframework.web.servlet.mvc.simplecontrollerhandleradapter" />
<!-- viewresolver -->
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>
<mvc:annotation-driven />
<!-- 处理器 -->
<!-- <bean name="/hello" class="com.mvc.jn.controller.helloworldcontroller"/> -->
<context:component-scan base-package="com"/>
</beans>
controller 的目录结构如下：
（2）这个问题解决之后，又报错：
no mapping found for http request with uri [/exam3/web-inf/jsp/welcome.jsp] in dispatcherservlet with name 'spring2'
结果发现是web.xml配置得有问题，下面是有问题的：
<servlet>
<servlet-name>spring2</servlet-name>
<servlet-class>org.springframework.web.servlet.dispatcherservlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<url-pattern>/*</url-pattern>
</servlet-mapping>
解决方法：把url-pattern 由/* 改为/