Spring MVC - HandlerInterceptor (X 라고 가정)

13> HandlerInterceptor (X 라고 가정)
- 기본적인 Spring MVC 아키텍쳐에서 3군데 위치에서 가로채기 가능
  Controller 요청전/요청후 와 jsp 응답전에서 HandlerInterceptor(가로채기) 사용가능.
- Spring MVC 아키텍쳐

  웹브라우저 -------필터-------> DispatcherServlet---(X)---->Controller------->Service------->Repository
                                     |                                      <---(X)-----               <--------          <--------
                                     |
                                     |
                                    jsp
            <--------(X)-----------

- 구현방법
(1) implements HandlerInterceptor
(2) 필요한 3개의 메서드 재정의 가능 (default 메서드)

    # Controller 호출전에 실행 (주요기능 ex> 로그인 여부 확인작업,...)
    // DispatcherServlet -> Controller
    @Override
    public boolean preHandle(
        HttpServletRequest request, 
        HttpServletResponse response, 
        Object handler) 
            throws Exception {
      System.out.println("Controller 요청전 호출: preHandle 메서드" + handler);
      // 주요 작업: 로그인 여부 확인
      
      return true;
    }

    # Controller 호출후에 실행 (주요기능 ex> View 변경 및 Model 추가/수정)
    // Controller -> DispatcherServlet
    @Override
    public void postHandle(
        HttpServletRequest request, 
        HttpServletResponse response, 
        Object handler,
        ModelAndView mav) 
            throws Exception {

      System.out.println("Controller 요청후 호출: postHandle 메서드");
      // view 변경 가능 및 Model 추가/변경
      mav.setViewName("main"); // main.jsp 로 변경
      mav.addObject("model", "홍길동"); // model 값
    }

    # JSP 웹브라우저에 랜더링 된후 실행
    // DispatcherServlet-jsp -> 웹브라우저
    @Override
    public void afterCompletion(
        HttpServletRequest request, 
        HttpServletResponse response, 
        Object handler, 
        Exception ex)
        throws Exception {

      System.out.println("jsp 가 웹브라우저에 랜더링된 후 호출: afterCompletion 메서드");
    }

(3) web.xml 역할의 @Configuration 으로 지정된 빈을 만들어서 HandlerInterceptor 등록.

  @Configuration
  public class WebConfig implements WebMvcConfigurer {

    @Autowired
    MyHandlerInterceptor myHandlerInterceptor;
    
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
      registry.addInterceptor(myHandlerInterceptor)
              .addPathPatterns("/login","/logout");
    }
  }

package com.exam;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;


@SpringBootApplication
public class Application {

	public static void main(String[] args) {
		SpringApplication.run(Application.class, args);
	}
}

package com.exam.config;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

import com.exam.interceptor.MyHandlerInterceptor;

@Configuration
public class WebConfig implements WebMvcConfigurer {

	@Autowired
	MyHandlerInterceptor myHandlerInterceptor;
	
	@Override
	public void addInterceptors(InterceptorRegistry registry) {
		registry.addInterceptor(myHandlerInterceptor)
		        .addPathPatterns("/login","/logout");
	}

	
	
}

package com.exam.controller;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;

@Controller
public class MainController {
	
	Logger logger = LoggerFactory.getLogger(getClass());

	@GetMapping("/login")
	public String login() {
		logger.info("logger:login 요청");
		return "hello";
	}
	
	@GetMapping("/mypage")
	public String mypage() {
		logger.info("logger:mypage 요청");
		return "hello";
	}
	
	@GetMapping("/logout")
	public String logout() {
		logger.info("logger:logout 요청");
		return "hello";
	}
}

package com.exam.interceptor;

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

import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

@Component("interceptor")
public class MyHandlerInterceptor implements HandlerInterceptor {

	@Override
	public boolean preHandle(HttpServletRequest request, 
			                 HttpServletResponse response, 
			                 Object handler)
			throws Exception {
		System.out.println("Controller 요청전 호출: preHandle 메서드" + handler);
		// 주요 작업: 로그인 여부 확인
		return true;
	}
	@Override
	public void postHandle(HttpServletRequest request, 
			               HttpServletResponse response, 
			               Object handler,
			               ModelAndView mav) throws Exception {
		System.out.println("Controller 요청후 호출: postHandle 메서드");
		// view 변경 가능 및 Model 추가/변경
		mav.setViewName("main");
		mav.addObject("model", "홍길동");
	}
	@Override
	public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
			throws Exception {
		System.out.println("jsp가 웹브라우저에 랜더링된 후 호출: afterCompletion 메서드");
	}
}

<%@ page 
         contentType="text/html; charset=UTF-8"
         pageEncoding="UTF-8"        
%>

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<h2>hello.jsp</h2>
</body>
</html>

<%@ page 
         contentType="text/html; charset=UTF-8"
         pageEncoding="UTF-8"        
%>

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<h2>main.jsp</h2>
model:${model}<br>
</body>
</html>

# application.properties
logging.level.org.springframework=info

# tomcat port 번호 변경
server.port=8090

# context 명 변경
server.servlet.context-path=/app

# jsp의 경로와 확장자 지정
spring.mvc.view.prefix=/WEB-INF/views/
spring.mvc.view.suffix=.jsp

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 
	http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.7.18</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.exam</groupId>
	<artifactId>demo</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>demo</name>
	<description>Demo project for Spring Boot</description>
	<properties>
		<java.version>11</java.version>
	</properties>
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
<!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-devtools -->
		<dependency>
		    <groupId>org.springframework.boot</groupId>
		    <artifactId>spring-boot-devtools</artifactId>
		</dependency>
	<dependency>
		<groupId>org.apache.tomcat.embed</groupId>
		<artifactId>tomcat-embed-jasper</artifactId>
		<scope>provided</scope>
	</dependency> 
	<dependency>
		<groupId>javax.servlet</groupId>
		<artifactId>jstl</artifactId>
	</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>

</project>