간단한 게시판 만들어 보기

1. DB 관련 세팅

demo6 DB 생성

create database demo6;
use demo6;

create table posts(
    id int auto_increment primary key, 
    title varchar(255) not null, 
    content text not null,
    created_at timestamp default current_timestamp
);

select * from posts;

com/tenco/servelet/DBUtil.java

DB 접근 객체 만들어 보기 (기본)

package com.tenco.servlet;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class DBUtil {
	
	private static final String URL = "jdbc:mysql://localhost:3306/demo6?serverTimezone=Asia/Seoul";
	private static final String USER = "root";
	private static final String PASSWORD = "asd123";
	
	public static Connection getConnection() throws ClassNotFoundException, SQLException {
		Class.forName("com.mysql.cj.jdbc.Driver");
		return DriverManager.getConnection(URL, USER, PASSWORD);
	}
}

2. 게시글 작성

webapp/createPost.jsp

게시글 작성 화면 만들어 보기 (프레젠테이션 계층)

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>게시글 작성</title>
<link rel="stylesheet" type="text/css" href="css/styles.css">
</head>
<body>
    <h2>게시글 작성</h2>
    <form action="create-post" method="post">
        <label for="title"> 제목 : </label>
        <input type="text" name="title" id="title" value="게시글 제목 1">
        <br><br>
        <label for="content"> 내용 : </label>
        <input type="text" name="content" id="content" value="JSP 웹 프로그래밍 ....">
        <button type="submit">글 작성</button>
    </form>
    <br>
    <a href="read-posts">게시글 목록</a>
</body>
</html>

com.tenco.servlet/CreatePostServlet.java

게시글 작성 기능 만들기 (비즈니스 로직 계층)

package com.tenco.servlet;

import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;

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

@WebServlet("/create-post")
public class CreatePostServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	public CreatePostServlet() {
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// 기본 값 설정 (언어 설정)
		request.setCharacterEncoding("UTF-8");

		// HTTP 요청 메시지에서 데이터 추출
		String title = request.getParameter("title");
		String content = request.getParameter("content");
		
		// 인증 검사 생략 (로그인 여부 확인)
		// 데이터 유효성 검사는 생략 ...

		try (Connection conn = DBUtil.getConnection()) {
			String sql = " INSERT INTO posts(title, content) VALUES (?,?) ";
			PreparedStatement pstmt = conn.prepareStatement(sql);
			pstmt.setString(1, title);
			pstmt.setString(2, content);
			pstmt.executeUpdate();
			
			response.sendRedirect("result.jsp?message=create-success");
		} catch (Exception e) {
			e.printStackTrace();
			response.sendRedirect("result.jsp?message=error");
		}
	}

}

webapp/result.jsp

결과 확인 페이지 만들어 보기

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>결과 확인 페이지</title>
</head>
<body>
    <h2>결과 확인 페이지</h2>
    <% 
    	String message = request.getParameter("message");
    	if ("create-success".equalsIgnoreCase(message)){
    		out.println("<p>게시글 작성을 성공했습니다. </p>");
    	} else if ("error".equalsIgnoreCase(message)){
    		out.println("<p>작업 실패</p>");
    	} else if ("delete-success".equalsIgnoreCase(message)) {
    		out.println("<p>게시글 삭제를 성공했습니다.</p>");
    	} else if ("update-success".equalsIgnoreCase(message)){
    		out.println("<p>게시글 수정을 성공했습니다.</p>");
    	}
    %>
    <br>
    <%-- 게시글 작성 화면으로 이동 --%>
    <a href="createPost.jsp"> 게시글 작성 페이지  </a>

    <%-- 게시글 작성 화면으로 이동 --%>
    <a href="read-posts"> 게시글 목록 페이지  </a>
</body>
</html>

3. 게시글 목록 조회

com.tenco.servlet/ReadPostsServlet.java

게시글 목록 기능 만들기 (비즈니스 로직 계층)

package com.tenco.servlet;

import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

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

@WebServlet("/read-posts")
public class ReadPostServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	public ReadPostServlet() {
		super();
	}

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// 응답 처리 MIME TYPE 설정
		response.setContentType("text/html;charset=UTF-8");
		try (Connection conn = DBUtil.getConnection()) {
			String sql = " SELECT * FROM posts ORDER BY created_at DESC ";
			PreparedStatement pstmt = conn.prepareStatement(sql);
			ResultSet rs = pstmt.executeQuery();
			
			request.setAttribute("resultSet", rs);
			request.getRequestDispatcher("readPosts.jsp").forward(request, response);
		} catch (Exception e) {
			// TODO: handle exception
		}
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	}

}

: request.getRequestDispatcher("readPosts.jsp").forward(request, response); 활용

webapp/readPost.jsp

게시글 목록 화면 만들어 보기 (프레젠테이션 계층)

<%@page import="java.sql.ResultSet"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>게시글 목록</title>
<link rel="stylesheet" type="text/css" href="css/styles.css">
</head>
<body>
    <h2>게시글 목록</h2>
    <%
    	ResultSet rs = (ResultSet) request.getAttribute("resultSet");
    	if (rs != null) {
    %>
    <table border="1">
        <tr>
            <th>ID</th>
            <th>제목</th>
            <th>작성일</th>
            <th>액션</th>
        </tr>
        <% while (rs.next()) {%>
        	<tr>
                <td><%=rs.getInt("id") %></td>
                <td><%=rs.getString("title") %></td>
                <td><%=rs.getString("created_at") %></td>
                <td>
                    <form action="delete-post" method="get">
                    	<input type="hidden" name="boardId" value="<%=rs.getInt("id") %>">
                        <button type="submit">삭제</button>
                    </form>
                </td>
            </tr>
        <% } %>
    </table>
    <% } else { %>
    	<p>작성된 게시글이 하나도 없습니다.</p>
    <% } %>	
</body>
</html>

4. 게시글 삭제

com.tenco.servlet/DeletePostServlet.java

게시글 삭제 기능 만들어 보기(비즈니스 로직 계층)

package com.tenco.servlet;

import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;

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

@WebServlet("/delete-post")
public class DeletePostServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    public DeletePostServlet() {
        super();
    }

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		request.setCharacterEncoding("UTF-8");
		String id = request.getParameter("boardId");
		System.out.println("id : " + id);
		
		try (Connection conn = DBUtil.getConnection()) {
			String sql = " DELETE FROM posts WHERE id = ? ";
			PreparedStatement pstmt = conn.prepareStatement(sql);
			pstmt.setInt(1, Integer.parseInt(id));
			pstmt.executeUpdate();
			
			// 클라이언트에게 새로운 URL를 자동으로 요청하도록 HTTP 응답을 보낸다.
			// HTTP 상태 코드 302(임시 이동) 사용자에게 새로운 URL로 이동처리 시킨다.
			response.sendRedirect("result.jsp?message=delete-success");
		} catch (Exception e) {
			response.sendRedirect("result.jsp?message=error");
		}
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	}

}

5. 게시글 상세보기, 수정

com.tenco.servlet/DetailPostServlet.java

게시글 상세 보기 기능 만들기(비즈니스 로직 계층)

package com.tenco.servlet;

import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

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

@WebServlet("/view-post")
public class DetailPostServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	public DetailPostServlet() {
		super();
	}

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		response.setContentType("text/html;charset=UTF-8");
		String id = request.getParameter("boardId");
		
		try (Connection conn = DBUtil.getConnection()){
			String sql = " SELECT * FROM posts WHERE id = ? ";
			PreparedStatement pstmt = conn.prepareStatement(sql);
			pstmt.setInt(1, Integer.parseInt(id));
			ResultSet rs = pstmt.executeQuery();
			
			request.setAttribute("resultSet", rs);
			request.getRequestDispatcher("detailPost.jsp").forward(request, response);
		} catch (Exception e) {
			e.printStackTrace();
			response.sendRedirect("result.jsp?message=error");
		}
	}

}

: request.getRequestDispatcher("detailPost.jsp").forward(request, response); 활용

webapp/detailPost.jsp

게시글 상세보기 화면 (프레젠테이션 계층)

<%@page import="java.sql.ResultSet"%>
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>게시글 상세보기 화면</title>
</head>
<body>
	<h2>상세보기 화면</h2>
	<%
	ResultSet rs = (ResultSet) request.getAttribute("resultSet");
	if (rs.next()) {
	%>
	<h3><%=rs.getString("title") %></h3>
	<p><%=rs.getString("content") %></p>
	<p><small> 작성일 : <%=rs.getString("created_at") %></small></p>
    <!-- 수정 폼-->
    <h3>게시글 수정</h3>
    <form action="update-post" method="post">
        <input type="hidden" name="boardId" value="<%=rs.getInt("id") %>">
        <label for="title">제목 : </label>
        <input type="text" name="title" id="title" value="<%=rs.getString("title") %>">
        <br><br>
        <label for="content">내용 : </label>
        <input type="text" name="content" id="content" value="<%=rs.getString("content") %>">
        <button type="submit">수정하기</button>
    </form>
	<%
	}
	%>
</body>
</html>

com.tenco.servlet/UpdatePostServlet.java

게시글 수정 기능 만들기 (비즈니스 로직 계층)

package com.tenco.servlet;

import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;

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

@WebServlet("/update-post")
public class UpdatePostServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	public UpdatePostServlet() {
		super();
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		request.setCharacterEncoding("UTF-8");
		// 일반적인 로직 수정 - 권한확인 확인 (세션정보, 작성자 정보 비교)
		String id = request.getParameter("boardId");
		// SELECT * FROM posts WHERE id = 3; <-- 작성자
		
		// 유효성 검사 (사용자 새로 입력한 정보가 유효한지 검사)
		
		// Update 구문 처리
		// 트랜잭션 처리를 해야 한다. (commit, rollback)
		
		String title = request.getParameter("title");
		String content = request.getParameter("content");
		
		try (Connection conn = DBUtil.getConnection()){
			String sql = " UPDATE posts SET title = ? , content = ? WHERE id = ? ";
			PreparedStatement pstmt = conn.prepareStatement(sql);
			pstmt.setString(1, title);
			pstmt.setString(2, content);
			pstmt.setInt(3, Integer.parseInt(id));
			pstmt.executeUpdate();
			response.sendRedirect("result.jsp?message=update-success");
		} catch (Exception e) {
			response.sendRedirect("result.jsp?message=error");
		}
	}

}

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1. DB 관련 세팅

2. 게시글 작성

3. 게시글 목록 조회

4. 게시글 삭제

5. 게시글 상세보기, 수정

'Java > JSP' 카테고리의 다른 글

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