[Java知识库]第一个spring mvc程序

1、利用IDEA新建一个普通的maven项目，通过添加框架支持，使普通的maven项目变成Javaweb项目。

2、在pom.xml中添加依赖

<dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.3.15</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.20</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>javax.servlet.jsp-api</artifactId>
            <version>2.3.3</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>servlet-api</artifactId>
            <version>2.5</version>
        </dependency>
    </dependencies>

3、配置web.xml，注册DispatcherServlet

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">
    <!--配置DispatcherServlet-->
    <servlet>
        <servlet-name>dispatcherServlet</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:dispatcherServlet.xml</param-value>
        </init-param>
        <!-- 表示容器再启动时立即加载dispatcherServlet -->
        <load-on-startup>1</load-on-startup>
    </servlet>
    <!--所有的url请求都会通过DispatcherServlet-->
    <servlet-mapping>
        <servlet-name>dispatcherServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

4、编写spring的配置文件dispatcherServlet.xml

<?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">

    <!-- 配置处理器映射器,根据url找到duiyid的bean，返回前端控制器-->
    <bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping" />
    <!-- 配置处理器适配器，收到前端控制器的handle，找到对应的Contrller -->
    <bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter" />
    <!-- 配置视图解析器，收到前端控制器的modelview，返回解析后的view名-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <!-- 自动补充前缀-->
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <!-- 自动补充后缀-->
        <property name="suffix" value=".jsp"/>
    </bean>
</beans>

5、编写HelloController实现Controller接口

public class HelloController implements Controller {
    @Override
    public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
        ModelAndView modelAndView = new ModelAndView();
        //以对象的方式添加
        modelAndView.addObject("msg","hello spring mvc");

        //指定跳转页面，实际url：/WEB-INF/jsp/hello.jsp
        modelAndView.setViewName("hello");
        return modelAndView;
    }
}

6、在spring的配置文件dispatcherServlet.xml注册

<?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">

    <!-- 配置处理器映射器,根据url找到duiyid的bean，返回前端控制器-->
    <bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping" />
    <!-- 配置处理器适配器，收到前端控制器的handle，找到对应的Contrller -->
    <bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter" />
    <!-- 配置视图解析器，收到前端控制器的modelview，返回解析后的view名-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <!-- 自动补充前缀-->
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <!-- 自动补充后缀-->
        <property name="suffix" value=".jsp"/>
    </bean>

    <!--handle，注册bean-->
    <bean id="/hello" class="com.wen.controller.HelloController"/>

</beans>

7、编写要跳转的jsp页面，显示modelview存放的数据。以及我们的正常页面

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>$Title$</title>
</head>
<body>
${msg}
</body>
</html>

8、配置tomcat进行测试