springmvc搭建环境时报No mapping found for HTTP request with URI [/exam3/welcome] in DispatcherServlet with name 'spring2'

项目是使用spring MVC

（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 -->
    <bean
        class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter" />
    <!-- ViewResolver -->
    <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>
<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>
        <servlet-name>spring2</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>

 解决方法：把url-pattern 由/* 改为/