Spring MVC is new – starting from scratch

Introduction to Spring MVC

Spring MVC is a lightweight web framework based on the MVC architecture pattern that is designed to modularize web development and decouple the overall architecture.

Spring MVC has some advantages:

As part of the spring framework, it has the advantages of spring (IOC,AOP, etc.)

Supports flexible URL-to-page-controller mapping

Provides flexible data validation, formatting, and data-binding mechanisms

Support RESTful style

Spring MVC Request Process

The overall request flow for the Spring MVC framework is as follows:

Several functional components of spring MVC are involved:

Front-end controller (dispatcherservlet): Receives a user request and returns the result of the request. It acts as a transponder or central processing unit, controls the entire execution process, and reduces the coupling between components that are progressively scheduled.

Processor Mapper (handlermapping): Based on the URL requested by the user, through annotations or XML configuration, to find the appropriate processor handler

processor Adaptation (Handleradapter): Complete the method in the calling processor based on the handler found by the Mapper

Processor (Handler): Request processing of specific logic, return data and view information

view Resolver: Resolves a specific view that resolves a logical view name into a real view by Modelandview The view information in the object

Detailed steps in the request process:

1: The user initiates the request and the request is intercepted by the front-end controller (dispatcherservlet)

2: Front Controller (dispatcherservlet) Request Processor Mapper (handlermapping) lookup Handler

3: Processor Mapper (handlermapping) finds corresponding handler (can be more annotated or XML configuration) based on configuration, may contain multiple interceptor interceptors, return to front Controller

4: Front Controller (dispatcherservlet) Request processor Adapter (Handleradapter) to perform the corresponding handler

5: Adapter is assigned to the corresponding handler processor

Return Modelandview object to processor adapter after 6:handler processor finishes executing

7: The processor adapter accepts the return result of the handler processor and returns the result to the front-end controller (dispatcherservlet)

8: Front Controller (Dispatcherservlet) receives the data and view information returned by the processor adapter, requests the View resolver, resolves the corresponding view

9: The view resolver returns to the front-end controller based on the corresponding view results matching the View information

10: Front controller receives a specific view, renders the view, fills the model data into the view view, and produces the final view

11: Front Controller returns results to user

Build your demo project from scratch:

Create a new Dynamic Web project under Eclipse

Project default directory structure:

Add a Jar package dependency

WebContent > Web-inf > lib folder to import the corresponding jar package, The core of the jar package is Spring-webmvc-5.0.0.release.jar, and the others are mostly spring for managing contexts and Beande packages, jstl tag libraries, and a log package for printing logs:

Configuring the front-end controller in Web. xml

The front-end controller is the equivalent of Spring MVC's proprietary servlet for intercepting all eligible requests and handing them over to the framework

<?XML version= "1.0" encoding= "UTF-8"?><Web-appXmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance"xmlns= "Http://xmlns.jcp.org/xml/ns/javaee"xsi:schemalocation= "Http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"ID= "webapp_id"version= "3.1">          <!--Configuring the front-end controller-dispatchservlet -  <servlet>  <Servlet-name>Springmvcnext</Servlet-name>  <Servlet-class>Org.springframework.web.servlet.DispatcherServlet</Servlet-class>  <!--Contextconfiglocation is not required, if Contextconfiglocation is not configured, the SPRINGMVC configuration file defaults to: Web-inf/servlet name+ "-servlet.xml "  -  <Init-param>          <Param-name>Contextconfiglocation</Param-name>        <Param-value>Classpath:applicationContext.xml</Param-value>  </Init-param>  </servlet>    <servlet-mapping>  <Servlet-name>Springmvcnext</Servlet-name>  <Url-pattern>/</Url-pattern> <!--block requests from users based on rules set by Url-pattern block all requests here, including static resources, </servlet-mapping> </  web-app> 

Where the URL matching rules defined in the <servlet-mapping> tag are in the form of *.action, the corresponding servlet is named Springmvcnext, and the <servlet> The controller configured is Org.springframework.web.servlet.DispatchServlet, which is the front-end controller for the current SPRINGMVC project,<init-param> The tag is the parameter that the current controller depends on, and two parameters represent the context parameter and the parameter loading path.

About Classpath: Represents the compiled output path for a Web project after compilation

Configure the Spring MVC configuration

Add the Applicationcontext.xml file in the Java source code directory

Specific content:

<?XML version= "1.0" encoding= "UTF-8"?><Beansxmlns= "Http://www.springframework.org/schema/beans"Xmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance"xmlns:p= "http://www.springframework.org/schema/p"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/security http://www.springframework.org/schema/security/ Spring-security.xsd Http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/ Spring-mvc-4.0.xsd Http://www.springframework.org/schema/context http://www.springframework.org/schema/context/ Spring-context.xsd ">    <!--the package scanner label will be used to activate the spring MVC Comment scanning feature, allowing annotations such as @controller and @requestmapping to be used.  -    <Context:component-scanBase-package= "Com.sl.controller" />        <!--Note Driver -    <Mvc:annotation-driven/>        <!--Configuring the View resolver -    <Beanclass= "Org.springframework.web.servlet.view.InternalResourceViewResolver"ID= "Internalresourceviewresolver">        < Propertyname= "prefix"value= "/web-inf/view/" />        < Propertyname= "suffix"value= ". jsp" />    </Bean></Beans>

Adding controller controllers and Views view

Add the package Com.sl.controller under the SRC directory and add the controller code as follows:

 PackageCom.sl.controller;ImportOrg.springframework.stereotype.Controller;Importorg.springframework.web.bind.annotation.RequestMapping;ImportOrg.springframework.web.servlet.ModelAndView; @Controller Public classHelloworldcontroller {@RequestMapping ("/index")//handles all requests beginning with/index in the URL path: including/index/* and/index.html     PublicModelandview HelloWorld () {String message= "Hello Spring MVC"; return NewModelandview ("index", "message", message); }}

Add a view file in Web-inf/view index.jsp

<HTML><Head>    <title>Spring MVC</title></Head><Body>${message}</Body></HTML>

Operation Result:

Spring MVC is new – starting from scratch