01-初始springmvc

初始springmvc

最典型的mvc就是jsp+servlet+JavaBean的模式

我们为什么要学习SpringMVC呢?

Spring MVC的特点:

1. 轻量级，简单易学
2. 高效，基于请求响应的MVC框架
3. 与Spring兼容性好，无缝结合
4. 约定优于配置
5. 功能强大:RESTful、数据验证、格式化、本地化、主题等
6. 简洁灵活

HelloSpringMvc

1.新建一个module，添加web的支持！

2.确定导入了springmvc的依赖

    <dependencies>

    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>

    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>5.2.0.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>servlet-api</artifactId>
        <version>2.5</version>
    </dependency>
    <dependency>
        <groupId>javax.servlet.jsp</groupId>
        <artifactId>jsp-api</artifactId>
        <version>2.2</version>
    </dependency>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>jstl</artifactId>
        <version>1.2</version>
    </dependency>
</dependencies>
    <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>

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">
<!--注册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>
    <init-param>
        <param-name>contextConfigLocation</param-name>
<!--    关联一个配置文件springmvc-servlet.xml    -->
        <param-value>classpath:springmvc-servlet.xml</param-value>
    </init-param>
        <!--    启动级别    -->
        <load-on-startup>1</load-on-startup>
    </servlet>

<!--   /   匹配所有的请求（不包括.jsp）
       /*   匹配所有的请求（包括.jsp）
-->
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

4.编写springmvc-servlet.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">
<!--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>

    <bean id="/hello" class="com.kuang.controller.HelloController"/>
</beans>

5.写com.kuang.controller.HelloController类

package com.kuang.controller;

import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.Controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//注意：这里我们先导入Controller接口
public class HelloController implements Controller {
    public ModelAndView handleRequest(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {
        ModelAndView mv=new ModelAndView();
        //封装对象，放在ModelView中 （业务代码）
        mv.addObject("msg","HelloSpringMVC!");
        
        //视图跳转
        mv.setViewName("hello");// 相当于WEB-INF/jsp/hello.jsp
        return mv;
    }
}

6.写WEB-INF/jsp下的hello.jsp

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

7.配置tomcat启动测试

可能遇到的问题:访问出现404。

排查步骤:

1. 查看控制台输出，看一下是不是缺少了什么jar包。
2. 如果jar包存在，显示无法输出，就在IDEA的项目发布中，添加lib依赖!

点击项目结构–>

3. 重启Tomcat 即可解决!

实际开发和这个有些区别，用的是注解版！注解版才是精髓！！！最主要的！！！