스프링 복습

yuzu sim

Jan 30, 2024

1. 프로젝트 만들기

view 확인하기

3. context path 삭제하기

4. index.jsp 파일 삭제하기

바로 접근이 가능하기 때문에 MVC 파일의 강제가 안됨

스프링의 template 폴더와 동일함

요청을 톰캣이 받음

→ 전송되는 정보를 파싱해서 request 객체를 만들어서 dispathcerServlet에 전달해줌


package com.example.myapp;

import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import java.io.IOException;

// http://localhost:8080/*.do 로 요청
@WebServlet("*.do") // 해당 주소를 무조건 연결
public class DispatcherServlet extends HttpServlet { // servlet이 됨 : 외부와 통신이 가능

    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        service(request, response);
    }
}


package com.example.myapp;

import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import java.io.IOException;

// http://localhost:8080/*.do 로 요청
@WebServlet("*.do") // 해당 주소를 무조건 연결
public class DispatcherServlet extends HttpServlet { // servlet이 됨 : 외부와 통신이 가능

    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println(request.getRequestURI());
    }
}

5. BoardController 만들기

dispatherServlet에서 분기가 가능


package com.example.myapp;

// 책임을 분리
public class BoardController {

    public void save(){
        System.out.println("글쓰기");
    }

    public void findAll(){
        System.out.println("글목록보기");
    }
}

6. DispatcherServlet 만들기


package com.example.myapp;

import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import java.io.IOException;

// http://localhost:8080/*.do 로 요청
@WebServlet("*.do") // 해당 주소를 무조건 연결
public class DispatcherServlet extends HttpServlet { // servlet이 됨 : 외부와 통신이 가능

    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println(request.getRequestURI());
        
        String action = request.getRequestURI()
                .replace("/", "")
                .split(".")[0];
    }
}

switch case문으로 분기하기


package com.example.myapp;

import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import java.io.IOException;

// http://localhost:8080/*.do 로 요청
@WebServlet("*.do") // 해당 주소를 무조건 연결
public class DispatcherServlet extends HttpServlet { // servlet이 됨 : 외부와 통신이 가능

    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println(request.getRequestURI());

        String action = request.getRequestURI()
                .replace("/", "")
                .split(".")[0];

        BoardController bc = new BoardController();
        switch (action) {
            case "save":
                bc.save();
                break;
            case "findAll":
                bc.findAll();
                break;
            default:
                response.getWriter().println("404 Not Found");
        }
    }
}

“.”을 인식하지 못함 → \\ 추가하기!


package com.example.myapp;

import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import java.io.IOException;

// http://localhost:8080/*.do 로 요청
@WebServlet("*.do") // 해당 주소를 무조건 연결
public class DispatcherServlet extends HttpServlet { // servlet이 됨 : 외부와 통신이 가능

    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println(request.getRequestURI());

        String action = request.getRequestURI()
                .replace("/", "")
                .split("\\.")[0];

        BoardController bc = new BoardController();
        switch (action) {
            case "save":
                bc.save();
                break;
            case "findAll":
                bc.findAll();
                break;
            default:
                response.getWriter().println("404 Not Found");
        }
    }
}

7. 컨트롤러에서 분기처리해서 글자 반환하기


package com.example.myapp.controller;

// 책임을 분리
public class BoardController {

    public String save(){
        return "<h1>board write</h1>";
    }

    public String findAll(){
        return "<h1>board list</h1>";
    }
}


package com.example.myapp;

import com.example.myapp.controller.BoardController;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import java.io.IOException;

// http://localhost:8080/*.do 로 요청
@WebServlet("*.do")
public class DispatcherServlet extends HttpServlet {

    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println(request.getRequestURI());

        String action = request.getRequestURI()
                .replace("/", "")
                .split("\\.")[0];

        BoardController bc = new BoardController();
        String result;
        switch (action) {
            case "save":
                result = bc.save();
                response.getWriter().println(result); // 변수 result를 출력
                break;
            case "findAll":
                result = bc.findAll();
                response.getWriter().println(result); // 변수 result를 출력
                break;
            default:
                response.getWriter().println("404 Not Found");
        }
    }
}

8. 어노테이션 만들어서 사용하기


package com.example.myapp;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface RequestMapping {
    String value(); // default "/"
}

어노테이션에서 value는 키워드, 생략 가능

method로 분리

어노테이션을 보고 호출 → reflextion


package com.example.myapp.controller;

import com.example.myapp.RequestMapping;

// 책임을 분리
public class BoardController {

    @RequestMapping("/save") // 키워드가 value(키 값 생략)라 가능함
    public String save(){
        return "<h1>board write</h1>";
    }

    public String findAll(){
        return "<h1>board list</h1>";
    }

    public String findById(){
        return "<h1>board one</h1>";
    }
}


package com.example.myapp;

import com.example.myapp.controller.BoardController;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import java.io.IOException;
import java.lang.annotation.Annotation;
import java.lang.reflect.Method;

// http://localhost:8080/*.do 로 요청
@WebServlet("*.do")
public class DispatcherServlet extends HttpServlet {

    private String getAction(String uri){
       return uri
                //.replace("/", "")
                .split("\\.")[0];
    }

    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String action = getAction(request.getRequestURI());
        BoardController bc = new BoardController();

        Method[] methods = bc.getClass().getDeclaredMethods();

        for(Method mt : methods){
            Annotation anno = mt.getDeclaredAnnotation(RequestMapping.class);
            if(anno instanceof RequestMapping) {
                RequestMapping rm = (RequestMapping) anno;
                if (rm.value().equals(action)) {
                    try {
                        String result = (String) mt.invoke(bc);
                        response.getWriter().println(result);
                        break;
                    } catch (Exception e) {
                        throw new RuntimeException();
                    }
                }
            }
        }
    }
}


package com.example.myapp.controller;

import com.example.myapp.RequestMapping;

// 책임을 분리
public class BoardController {

    @RequestMapping("/save") // 키워드가 value(키 값 생략)라 가능함
    public String save(){
        return "<h1>board write</h1>";
    }

    @RequestMapping("/findAll")
    public String findAll(){
        return "<h1>board list</h1>";
    }

    @RequestMapping("/findById")
    public String findById(){
        return "<h1>board one</h1>";
    }
}