// JoinOk.java

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

    ...

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

    private void actionDo(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		request.setCharacterEncoding("EUC-KR");

        name = request.getParameter("name");

        ...

        String query = "insert into member values('" + name + "', '" + id + "', '" + pw + "', '" + phone1 + "', '" + phone2 + "', '"+ phone3 + "', '" + gender + "')";
		
		try {
			Class.forName("oracle.jdbc.driver.OracleDriver");
			connection = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl" , "amy" , "tiger");
			stmt = connection.createStatement();
			int i = stmt.executeUpdate(query); //query 실행 개수 반환
			if(i == 1){ //성공
				response.sendRedirect("joinResult.jsp");
			} else { //실패
				response.sendRedirect("join.html");
			}
		}
        ...
    }
}

// LoginOk.java

@WebServlet("/LogInOk")
public class LogInOk extends HttpServlet {
	private static final long serialVersionUID = 1L;
	
    ...

    private void actionDo(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		id = request.getParameter("id");
		pw = request.getParameter("pw");
		
		String query = "select * from member where id = '" + id + "' and pw = '" + pw + "'";
		
		try {
			Class.forName("oracle.jdbc.driver.OracleDriver");
			connection = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl" , "amy" , "tiger");
			stmt = connection.createStatement();
			resultSet =  stmt.executeQuery(query);
			
            //값 가져오기
			while (resultSet.next()) {
				name = resultSet.getString("name");
                ...
			}
			
            //세션에 저장
			HttpSession httpSession = request.getSession();
			httpSession.setAttribute("name", name);
			httpSession.setAttribute("id", id);
			httpSession.setAttribute("pw", pw);
			
			response.sendRedirect("loginResult.jsp");
			
		}
    }
}

// ModifyOk.java
@WebServlet("/ModifyOk")
public class ModifyOk extends HttpServlet {
	private static final long serialVersionUID = 1L;
    ...
    private void actionDo(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		request.setCharacterEncoding("EUC-KR");
		httpSession = request.getSession(); //세션값으로 확인
		
		name = request.getParameter("name"); //form 에 입력된 값
        ...

        if(pwConfirm()){
			String query = "update member set name ='" + name + "', phone1= '" + phone1 + "', phone2 = '" + phone2 + "', phone3 = '" + phone3 + "', gender = '" + gender + "'";
			try {
				Class.forName("oracle.jdbc.driver.OracleDriver");
				connection = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl" , "amy" , "tiger");
				stmt = connection.createStatement();
				int i = stmt.executeUpdate(query);
				if(i ==1 ){
					httpSession.setAttribute("name", name); //이름이 수정될 경우
					response.sendRedirect("modifyResult.jsp");
				}
            }
        }
    }

    private boolean pwConfirm() {
		boolean rs = false;
		String sessionPw =  (String)httpSession.getAttribute("pw");
		if(sessionPw.equals(pw)) {
			rs = true;
		} else {
			rs = false;
		}
		return rs;
	}
}