[Spring] Basic Operating Sequence for Spring Projects

context.xml

 The context.xml file is a file contained in Tomcat that specifies the resources of the web application.

context.xml

<!-- web application will be reloaded.                                   -->
    <WatchedResource>WEB-INF/web.xml</WatchedResource>
    <WatchedResource>WEB-INF/tomcat-web.xml</WatchedResource>
    <WatchedResource>${catalina.base}/conf/web.xml</WatchedResource>

 When the Tomcat server runs, it reads the source code of web.xml according to the path specified in the WatchedResource tag in the context.xml file.

web.xml

 Web.xml is a file that allows you to set up multiple settings for a web application. The following setup codes are included and additional setup codes can be entered.

root-context path setting

<!-- The definition of the Root Spring Container shared by all Servlets and Filters -->
 <context-param>
  <param-name>contextConfigLocation</param-name>
  <param-value>/WEB-INF/spring/root-context.xml</param-value>
 </context-param>
 
 <!-- Creates the Spring Container shared by all Servlets and Filters -->
 <listener>
  <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
 </listener>

  The above code specifies the root-context.xml location to be used as a setup file using the param-value tag. Therefore, the spring project reads the setup information in root-context.xml, but is currently empty because the database is not connected.

Register DispatcherServlet, settings

<!-- Processes application requests -->
 <servlet>
  <servlet-name>appServlet</servlet-name>
  <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
  <init-param>
   <param-name>contextConfigLocation</param-name>
   <param-value>/WEB-INF/spring/appServlet/servlet-context.xml</param-value>
  </init-param>
  <load-on-startup>1</load-on-startup>
 </servlet>
    <servlet-mapping>
  <servlet-name>appServlet</servlet-name>
  <url-pattern>/</url-pattern>
 </servlet-mapping>

 The above code specifies a servlet named DispatcherServlet and a servlet settings file. Like root-context, spring project runs and reads the setup information in servlet-context.xml.

필터 설정

 <!-- 한글 처리를 위한 인코딩 필터 -->
 <filter>
  <filter-name>encoding</filter-name>
  <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
  <init-param>
   <param-name>encoding</param-name>
   <param-value>UTF-8</param-value>
  </init-param>
 </filter>
 <filter-mapping>
  <filter-name>encoding</filter-name>
  <url-pattern>/*</url-pattern>
 </filter-mapping>

 It is not in the project that was created by default, but it is a necessary code to facilitate the processing of Hangul. Therefore, you need to add the code to web.xml that sets the encoding to utf-8 as shown above.

servlet-context.xml

servlet.xml is a file that allows you to set up a DispatchServlet.

servlet-context.xml

<!-- Enables the Spring MVC @Controller programming model -->
 <annotation-driven />

 <!-- Handles HTTP GET requests for /resources/** by efficiently serving up static resources in the ${webappRoot}/resources directory -->
 <resources mapping="/resources/**" location="/resources/" />

 <!-- Resolves views selected for rendering by @Controllers to .jsp resources in the /WEB-INF/views directory -->
 <beans:bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
  <beans:property name="prefix" value="/WEB-INF/views/" />
  <beans:property name="suffix" value=".jsp" />
 </beans:bean>
 
 <context:component-scan base-package="com.example.spring01" />

Annotatio-driven is a tag that enables @Controller.

The blank setting in the middle attaches the path string "/WEB-INF/views/" as a prefix to the class with the @Controller, and as a suffix ". A setting that automatically pastes an extension string called jsp".

Controller

 A controller is a Java class file with an annotation named @Controller.

예시

@Controller
public class HomeController {
 
 private static final Logger logger = LoggerFactory.getLogger(HomeController.class);
 
 /**
  * Simply selects the home view to render by returning its name.
  */
 @RequestMapping(value = "/", method = RequestMethod.GET)
 public String home(Locale locale, Model model) {
  logger.info("Welcome home! The client locale is {}.", locale);
  
  Date date = new Date();
  DateFormat dateFormat = DateFormat.getDateTimeInstance(DateFormat.LONG, DateFormat.LONG, locale);
  
  String formattedDate = dateFormat.format(date);
  
  model.addAttribute("serverTime", formattedDate );
  
  return "home";
 }
 
}

 First of all, home methods are the key functions of the controller. The string that home methods return to is a web page that appears when you run a project. Originally, it should be a string indicating the path /WEB-INF/views/home.jsp, but the servlet-context.xml setting will only work if you enter the page name. I will explain the controller in detail in MVC pattern.

JSP page

home.jsp

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ page session="false" %>
<html>
<head>
 <title>Home</title>
</head>
<body>
<h1>
 Hello world!  
</h1>

<P>  The time on the server is ${serverTime}. </P>
</body>
</html>

The home.jsp page appears on the screen because the home method of the controller returned to the home.