국비지원 54일차 - Servlet Memo 수정 예시

MemoEditServlet

package my.memo;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.SQLException;

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

/**
 * Servlet implementation class MemoEditFormServlet
 */
@WebServlet({ "/MemoEditFormServlet", "/MemoEditForm" })
public class MemoEditFormServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
	private MemoDAO dao = new MemoDAO();
	
	protected void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {

		res.setContentType("text/html; charset=UTF-8");
		PrintWriter out=res.getWriter();
		//1.수정할 글번호 받기
		String idx=req.getParameter("idx");
		System.out.println(idx);
		//2.유효성 체크 - MemoList로 돌려보내기
		if(idx==null||idx.trim().isEmpty()) {
			res.sendRedirect("MemoList");
			return;
		}
		//3.MemoDao의 selectMemo(idx)==>반환타입 MemoVO유형
		MemoDAO dao= new MemoDAO();
		MemoVO m=null;
		try {
			m = dao.selectMemo(Integer.parseInt(idx));
			if(m==null) {
				out.println("<script>");
				out.println("alert('존재하지 않는 글이에요')");
				out.println("history.go(-1)");
				out.println("</script>");
				return;
			}
			
		} catch (Exception e) {
			out.println("<h3 style='color:red'>서버 에러: "+e+"</h3>");
			e.printStackTrace();
		}
		//4.input value값으로 받아온 메모내용 값을 출력하기
		out.println("<link rel='stylesheet' type='text/css' href='CSS/memo.css'>");
		out.println("<script src='js/memo.js'></script>");
		out.println("<div id='wrap'>");
		out.println("<form name='frm' action='MemoEdit' method='POST'>");
		out.println("<input type='hidden' name='idx' value='"+m.getIdx()+"'>");
		out.println("<table border=\"1\">");
		out.println("<tr><th colspan=\"2\"><h2>::한줄 메모장 수정::</h2></th></tr>");
		out.println("<tr><td width=\"20%\"><b>작성자</b></td>");
		out.println("<td width=\"80%\"><input type=\"text\" name=\"name\" value='"+m.getName()+"' placeholder=\"Name\" class=\"writer\"></td></tr>");
		out.println("<tr><td width=\"20%\"><b>메모내용</b></td><td width=\"80%\">");
		out.println("<input type=\"text\" name=\"msg\" value='"+m.getMsg()+"' placeholder=\"Message\" class=\"msg\"></td></tr>");
		out.println("<tr><td colspan=\"2\" style=\"text-align:center\">");
		out.println("<button type=\"button\" onclick=\"check()\">글수정하기</button>");
		out.println("<button type=\"reset\">다시쓰기</button></td></tr>");
		out.println("</table>");
		out.println("</form>");
		out.println("</div>");
		out.close();
	}

}

MemoDAO

package my.memo;

import java.sql.Connection;
import java.sql.Date;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import jdbc.util.DBUtil;

public class MemoDAO {
	Connection con;
	PreparedStatement ps;
	ResultSet rs;
	
	public int insertMemo(MemoVO memo) throws SQLException{
		try {
			con=DBUtil.getCon();
			//시퀀스명 : memo_seq
			String sql ="INSERT INTO memo(idx,name,msg,wdate)"
					+" VALUES(memo_seq.nextval, ?,?,sysdate)";
			ps = con.prepareStatement(sql);
			String name=memo.getName();
			String msg=memo.getMsg();
			ps.setString(1, name);
			ps.setString(2, msg);
			int n = ps.executeUpdate();
			return n;
		} finally {
			close();
		}
	}
	//select문 where절
	public MemoVO selectMemo(int idx) throws SQLException{
		try {
			con=DBUtil.getCon();
			String sql="SELECT * FROM MEMO WHERE IDX=?";
			ps=con.prepareStatement(sql);
			ps.setInt(1, idx);
			rs=ps.executeQuery();
			List<MemoVO> arr=makeList(rs);
			if(arr!=null||arr.size()==1) {
				return arr.get(0);
			}
			return null;
		}finally {
			close();
		}
	}
	
	//최근 쓴 글 순으로 모든 메모글 가져오기
	public List<MemoVO> listMemo() throws SQLException{
		try {
			con=DBUtil.getCon();
			String sql = "SELECT * FROM MEMO";
			ps=con.prepareStatement(sql);
			rs = ps.executeQuery();
			List<MemoVO> arr=makeList(rs);
			return arr;
		}finally {
			close();
		}
	}
	
	public List<MemoVO> makeList(ResultSet rs) throws SQLException{
		List<MemoVO> arr=new ArrayList<>();
		
		//idx,msg,name,date
		while(rs.next()) {
			int idx = rs.getInt("idx");
			String msg = rs.getString("msg");
			String name = rs.getString("name");
			Date date = rs.getDate("wdate");
			MemoVO m = new MemoVO(idx, name, msg, date);
			arr.add(m);
		}
		return arr;
	}
	
	public int deleteMemo(int idx) throws SQLException{
		try {
			con=DBUtil.getCon();
			String sql="DELETE FROM MEMO WHERE IDX=?";
			ps=con.prepareStatement(sql);
			ps.setInt(1, idx);			
			int n=ps.executeUpdate();
			return n;
		}finally {
			close();			
		}
	}
	
	public int updateMemo(MemoVO memo) throws SQLException{
		try {
			con=DBUtil.getCon();
			String sql="UPDATE MEMO set msg=?,name=? where idx=?";
			ps=con.prepareStatement(sql);
			ps.setInt(3, memo.getIdx());
			ps.setString(2, memo.getName());
			ps.setString(1, memo.getMsg());
			System.out.println(memo.getMsg());
			int n = ps.executeUpdate();
			return n;
		}finally {
			close();
		}
	}
	
	public void close() {
		try {
			if(rs!=null) rs.close();
			if(ps!=null) ps.close();
			if(con!=null) con.close();
		}catch(Exception e){
			System.out.println(e);
		}
	}
}

MemoEdit

package my.memo;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.SQLException;

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

/**
 * Servlet implementation class MemoEdit
 */
@WebServlet("/MemoEdit")
public class MemoEdit extends HttpServlet {
	private static final long serialVersionUID = 1L;
	private MemoDAO dao=new MemoDAO();
	protected void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
		//0. post방식일때 한글처리
		req.setCharacterEncoding("UTF-8");
		res.setContentType("text/html;charset=UTF-8");
		PrintWriter out = res.getWriter();
		//1.글번호, 작성자, 글내용값 받기
		String idx = req.getParameter("idx");//hidden data
		String name = req.getParameter("name");
		String msg = req.getParameter("msg");
		System.out.println(idx+name+msg);
		//2.유효성 체크 -> MemoList로 돌려보내기
		if(idx==null||name==null||idx.trim().isEmpty()||name.trim().isEmpty()) {
			res.sendRedirect("MemoList");
			return;
		}

		//3. MemoDAO 생성해서 updateMemo(MemoVO객체) 호출
		MemoVO memo = new MemoVO(Integer.parseInt(idx),name,msg,null);
		try {
			int n=dao.updateMemo(memo);
			String str =(n>0)? "수정 성공" : "수정 실패";
			out.println("<script>");
			out.println("alert('"+str+"');");
			out.println("location.href='MemoList'");
			out.println("</script>");
		}catch(SQLException e) {
			
		}
		//4. 그 실행 결과에 따라서 메시지 보여주고 페이지 이동(MemoList)
	
	}

}

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