SpringMVC-第一个SpringMVC工程

初识SpringMVC

第一步：创建普通maven工程

第二步：导入所需依赖

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-webmvc</artifactId>
    <version>5.3.14</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>2.1</version>
</dependency>
<dependency>
    <groupId>javax.servlet.jsp.jstl</groupId>
    <artifactId>jstl-api</artifactId>
    <version>1.2</version>
</dependency>
<dependency>
    <groupId>taglibs</groupId>
    <artifactId>standard</artifactId>
    <version>1.1.2</version>
</dependency>

第三步：添加web支持

第四步：在web.xml中配置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">
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springmvc-servlet.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

第五步：在资源路径下创建springmvc-servlet.xml配置文件，配置处理器映射器，处理器适配器，视图解析器

<?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
        https://www.springframework.org/schema/beans/spring-beans.xsd">
    <bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>
    <bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>
    <bean id="/hello" class="com.lizhi.controller.HelloServlet"/>
</beans>

第六步：创建HelloController实现Controller接口，并注册，id为路径

package com.lizhi.controller;

import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.Controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class HelloServlet implements Controller {
    @Override
    public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
        ModelAndView modelAndView = new ModelAndView();
        modelAndView.addObject("msg","HelloSpringMVC");
        modelAndView.setViewName("hello");
        return modelAndView;
    }
}

第七步：在WEB-INF文件夹下创建jsp文件夹，在jsp文件夹中创建hello.jsp

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

第八步：启动tomcat测试

使用注解开发

前四步如上

第五步：在springmvc-servlet中开启注解支持

<?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:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
                           https://www.springframework.org/schema/beans/spring-beans.xsd
                           http://www.springframework.org/schema/context
                           https://www.springframework.org/schema/context/spring-context.xsd
                           http://www.springframework.org/schema/mvc
                           https://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <context:component-scan base-package="com.lizhi.controller"/>
    <!--   Springmvc不处理静态文件-->
    <mvc:default-servlet-handler/>
    <!--

支持springmvc注解驱动
在spring中一般采用@RequestMapping来完成映射关系
要想让注解生效，则必须要向上下文注册DefaultAnnotationHandlerMapping
和一个AnnotationMethodHandlerMapping实例
这两个处理器分别是类级别和方法级别的
而annotation-driven则帮助我们自动完成了这两个类的配置

-->
    <mvc:annotation-driven/>

    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>

</beans>

第六步：创建Controller

package com.lizhi.controller;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;

@Controller
public class UserController {
    @GetMapping("login")
    public String login(Model model){
        //model对象是页面模型，可以在此对象中放入业务返回的前端需要的数据
        model.addAttribute("msg","请登录");
        return "login";
    }
}

第七步：在WEB-INF文件夹下创建jsp文件夹，在jsp文件夹中创建login.jsp

第八步：启动tomcat测试

如果出现404或者500错误可，尝试以下两种解决方案

在pom.xml中加入此段配置

<!--在build中配置resources，来防止我们资源导出出现的问题-->
<build>
    <resources>
        <resource>
            <directory>src/main/resources</directory>
            <includes>
                <include>**/*.properties</include>
                <include>**/*.xml</include>
            </includes>
            <filtering>true</filtering>
        </resource>
        <resource>
            <directory>src/main/java</directory>
            <includes>
                <include>**/*.properties</include>
                <include>**/*.xml</include>
            </includes>
            <filtering>true</filtering>
        </resource>
    </resources>
</build>

在artifact中加入lib目录，并将所需jar包导入其中