SpringMVC特点和配置

SpringMvc的特点：

1. 轻量级，简单易学
2. 高效，基于请求相应的MVC框架
3. 与spring兼容性好，无缝结合
4. 约定由于配置
5. 功能强大：RESTful、数据验证、格式化、本地化、主题等
6. 简单灵活

SpringMVC的配置

pom文件导入依赖：

 <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
    </dependency>
    <!--Spring项目支持-->
    <dependency>
    	<groupId>org.springframework</groupId>
    	<artifactId>spring-webmvc</artifactId>
    	<version>5.1.9.RELEASE</version>
    </dependency>
    <!--servlet的支持-->
    <dependency>
        <groupId>javax.servlet</groupId>
   		<artifactId>servlet-api</artifactId>
        <version>2.5</version>
    </dependency>
    <!--jsp的支持-->
    <dependency>
    	<groupId>javax.servlet.jsp</groupId>
   	 	<artifactId>jsp-api</artifactId>
   	 	<version>2.2</version>
    </dependency>
    <!--jsp的jstl标签库支持-->
    <dependency>
    	<groupId>javax.servlet</groupId>
    	<artifactId>jstl</artifactId>
    	<version>1.2</version>
    </dependency>
    <dependency>
    <groupId>org.springframework</groupId>
    	<artifactId>spring-context</artifactId>
    	<version>3.1.0.RELEASE</version>
    	<scope>runtime</scope>
    </dependency>

    <dependency>
    	<groupId>org.springframework</groupId>
    	<artifactId>org.springframework.web.servlet</artifactId>
    	<version>3.1.0.RELEASE</version>
    </dependency>

  <!--防止资源导出失败-->
	<build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
        </resources>
    </build>

配置web.xml，注册DispatcherServlet

<!--配置DispatcherServlet：这个是springMVC的核心；请求分发器，前端控制器-->
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <!--DispatcherServlet要绑定spring的配置文件-->
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springmvc-servlet.xml</param-value>
        </init-param>
        <!--启动级别为:1-->
        <load-on-startup>1</load-on-startup>
    </servlet>

    <!--
    在springMVC中, /  /*
    /:只匹配所有请求，不匹配jsp页面
    /*: 匹配所有请求，匹配jsp页面
    -->
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    
    <!--配置session过期时间-->
    <session-config>
    	<session-timeout>15</session-timeout>
    </session-config>

在resource目录下添加springMVC-servlet。xml配置文件，配置的形式与spring容器配置基本类似具体如下：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">

    <!-- 处理器映射器 -->
    <bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>

    <!-- 处理器适配器 -->
    <bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>

    <!-- 视图解析器 -->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"
          id="internalResourceViewResolver">
        <!-- 前缀 -->
        <property name="prefix" value="/WEB-INF/jsp/" />
        <!-- 后缀 -->
        <property name="suffix" value=".jsp" />
    </bean>

    <!--BeanNameUrlHandlerMapping :bean-->
    <bean id="/hello" class="com.he.controller.HelloController"/>

</beans>

controller

public class HelloController implements Controller {

    public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
        ModelAndView mv = new ModelAndView();

        //业务代码
        String result = "helloSpringMVC";
        mv.addObject("msg",result);

        //视图跳转
        mv.setViewName("test");

        return mv;
    }
}

可能遇到问题：访问出现了404，排查步骤:

1. 查看控制台输出，看一下是不是缺少了jar包
2. 如果jar包在，显示无法输出，就在idea的项目发布中，添加lib依赖。
3. 冲起Tomcat即可！

使用springMVC必须配置的三大件
处理器映射器、处理器适配器、视图解析器