springMVC acquaintance - configured version & version comment

First, the environment to build (maven project)

1, depending on:

<dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.0</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.1</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.1.9.RELEASE</version>
        </dependency>
    </dependencies>

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2, because the convention is larger than maven configure all the resources you need to configure the build, the problem of our resources to prevent the export of failure

<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>

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3, problems may be encountered: Access appears 404 troubleshooting steps:

(1) view the console output, look at what's missing is not the jar package.

(2) If the jar package exists, the display can not be output, on the IDEA project release, adding lib rely on!

(3) restart Tomcat can be solved!

 

 二、配置版

1、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">

    <!--1.注册DispatcherServlet-->
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet
        </servlet-class> 
        <!--关联一个springmvc的配置文件:【servlet-name】-servlet.xml-->
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springmvc-servlet.xml</param-value>
        </init-param> 
        <!--启动级别-1-->
        <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>

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2、编写SpringMVC 的 配置文件！名称：springmvc-servlet.xml : [servletname]-servlet.xml（和xml中配的名称一样就可以）

<?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">

    <bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping" />
    <bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter "/>
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"
          id="InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>
    <!--Handler-->
    <bean id="/hello" class="com.me.controller.HelloController"/>

</beans>

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注：（1）如果这个文件中出现中文访问可能出现500

　　（2）处理映射器是：<bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/> 

　　（3）处理器适配器是：<bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/> 

　　（4）视图解析器：

<!--视图解析器:DispatcherServlet给他的ModelAndView--> <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>

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3、编写我们要操作业务Controller ，要么实现Controller接口，要么增加注解；需要返回一个ModelAndView，装数据，封视图；

package com.me.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 request, HttpServletResponse response) throws Exception {
        System.out.println(this.getClass()+"王正帅");
        //ModelAndView 模型和视图
        ModelAndView mv = new ModelAndView(); //封装对象，放在ModelAndView中。Model
        mv.addObject("msg", "HelloSpringMVC!");
        //封装要跳转的视图，放在ModelAndView中
        mv.setViewName("hello");
        //: /WEB-INF/jsp/hello.jsp
        return mv;
    }
}

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4、将自己的类交给SpringIOC容器，注册bean  ：<bean id="/hello" class="com.me.controller.HelloController"/>

5、写要跳转的jsp页面，显示ModelandView存放的数据，以及我们的正常页面；

<%--
  Created by IntelliJ IDEA.
  User: hp
  Date: 2020/4/1
  Time: 18:16
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>hello</title>
  </head>
  <body>
  ${msg}
  </body>
</html>

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6、运行测试

 

 三、注解版

1、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">

    <!--1.注册DispatcherServlet-->
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet
        </servlet-class>
        <!--关联一个springmvc的配置文件:【servlet-name】-servlet.xml-->
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springmvc-servlet.xml</param-value>
        </init-param>
        <!--启动级别-1-->
        <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>

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2、编写SpringMVC 的 配置文件！名称：springmvc-servlet.xml : [servletname]-servlet.xml（和xml中配的名称一样就可以）

<?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
       http://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.me.controller"/>
    <mvc:default-servlet-handler/>
    <mvc:annotation-driven/>
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver "
          id="internalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>
</beans>

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说明：

　　（1）自动扫描包，让指定包下的注解生效,由IOC容器统一管理：<context:component-scan base-package="com.me.controller"/>

　　（2）让Spring MVC不处理静态资源 （css、js等） ：<mvc:default-servlet-handler />

　　（3）支持mvc注解驱动在spring中一般采用@RequestMapping注解来完成映射关系要想使@RequestMapping注解生效必须向上下文中注册DefaultAnnotationHandlerMapping和一个AnnotationMethodHandlerAdapter实例这两个实例分别在类级别和方法级别处理。而annotation-driven配置帮助我们自动完成上述两个实例的注入：<mvc:annotation-driven /> 

3、编写一个Java控制类：

package com.me.controller;

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

@Controller
public class HelloController {
    @RequestMapping("/hello")
    public String hello(Model model){
        model.addAttribute("msg","hello,springMVC!");
        return "hello";
    }
}

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说明：

　　（1）@Controller是为了让Spring IOC容器初始化时自动扫描到；

　　（2）@RequestMapping是为了映射请求路径，这里因为类与方法上都有映射所以访问时应该是/HelloController/hello；

　　（3）方法中声明Model类型的参数是为了把Action中的数据带到视图中；

　　（4）方法返回的结果是视图的名称hello，加上配置文件中的前后缀变成WEB-INF/jsp/hello.jsp。 

4、在WEB-INF/ jsp目录中创建hello.jsp ， 视图可以直接取出并展示从Controller带回的信息；可以通过EL表示取出Model中存放的值，或者对象；

<%--
  Created by IntelliJ IDEA.
  User: hp
  Date: 2020/4/1
  Time: 20:08
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>hello</title>
  </head>
  <body>
  ${msg}
  </body>
</html>

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5、运行测试

 

 注：使用注解比较快。