Nov 12 :

Kim·2020년 11월 12일

JSP

목록 보기

3/5

📌 built-in objects

request **
response **
out **
page (pageContext) *
config
session *
application *
exception

pageContext: can be used in ONLY ONE jsp file (like local variable in Java)
⊂ request : at least two jsp files receiving and sending each other(with submit)
⊂ session : can be used in jsp files which already declared session
⊂ application : can be shared in the whole projects (like field in Java)

⛄ test code
Test the scope of the four objects(pageContext, request, session, application)

👉 firstPage.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<%
	pageContext.setAttribute("name", "page man");  //insert 'page man' to "name"
	request.setAttribute("name","request man"); //same here
	session.setAttribute("name", "session man"); //same
	application.setAttribute("name", "application man"); //same
	// four of them have different name and attribute is simillar to variable (like java)
	
	System.out.println("firstPage.jsp");
	System.out.println("하나의 페이지 속성 "+pageContext.getAttribute("name"));
	System.out.println("하나의 request 속성 "+request.getAttribute("name"));
	System.out.println("하나의 session 속성 "+session.getAttribute("name"));
	System.out.println("하나의 application 속성 "+application.getAttribute("name"));
	
	request.getRequestDispatcher("secondPage.jsp").forward(request,response);
	//rd 안쓰고 한줄로 표현
	
	//==RequestDispatcher rd=request.getRequestDispatcher("successful.jsp?userid="+userid);
	//rd.forward(request,response);	  post
%>
</body>
</html>

👉 secondPage.jsp

<body>
하나의 페이지 속성 : <%=pageContext.getAttribute("name") %><br>
하나의 request 속성 : <%=request.getAttribute("name") %><br>
하나의 session 속성 : <%=session.getAttribute("name") %><br>
하나의 application 속성 : <%=application.getAttribute("name") %><br>
</body>

👉 thirdPage.jsp

<body>
하나의 페이지 속성 : <%=pageContext.getAttribute("name") %><br>
하나의 request 속성 : <%=request.getAttribute("name") %><br>
하나의 session 속성 : <%=session.getAttribute("name") %><br>
하나의 application 속성 : <%=application.getAttribute("name") %><br>
</body>

⛄ first pageahfm

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>main page</title>
</head>
<body>
	<form method='post' action='doMove.jsp'>
<table>
<table>
	<tr><td colspan=2><input type=text name=login size=12>
		<input type=submit value=go>
		</td>
	</tr>
</table>
</form>
</body>
</html>

Enter specific words and clicks,

<%
String login=request.getParameter("login");
String signin=request.getParameter("login");

if(login.equals("login")){
	RequestDispatcher rd=request.getRequestDispatcher("login.jsp?login="+login);
	rd.forward(request,response);
}else if (signin.equals("signin")) {
	RequestDispatcher rd=request.getRequestDispatcher("signin.jsp?signin="+signin);
	rd.forward(request,response);	  //post
}
%>

<title>login</title>
</head>
<body>
	<h3>LOGIN</h3>
</body>

<title>signin</title>
</head>
<body>
	<h3>SIGNIN</h3>
</body>

result

📌 Attribute

setAttribute : set the attribute(variable)
getAttribute : get the value of the attribute
removeAttribute : eliminate the attribute

📌 JSP action tag

<jsp:foawrd> & <jsp:param>

<jsp:forward page="secondPage.jsp">
	<jsp:param name="name" value="request man">
	</jsp:param>
</jsp:forward>

is exactly same as

System.out.println("하나의 request 속성 "+request.getAttribute("name"));
request.getRequestDispatcher("secondPage.jsp").forward(request,response);

<jsp:include> : jsp:include page="file name.jsp"
<jsp:useBean> : is replaced by Spirng
<jsp:setProperty> : is replaced by Spring
<jsp:getProperty> : is replaced by Spring

cookie : (나의) 웹브라우저가 내 컴퓨터의 하드디스크에 파일형태로 저장한 내 개인정보
Personal inforamtion which my web browser saves in hard disk as a file form.
Data remains after log out.
example_
Youtube search key words >> Javascript >> Save in my hard disk with file format
session : 내가 접속한 웹서버가 자기 메모리 내에 보관하는 내 개인정보
Personal information which web server(me access) saves in its own meomory.
Better security performance than cookie.
log out >> all the data deletes

Backend frameworks

Spring - Java
Django - Python for web site
TensorFlow for AI
Laravel - PHP

Racts.js - Javascript
Vue.js - Javascript
Angular - Javascript

Framework

example : Login login = new Login(); >> 기본 로그인창 생성

(1 page, 1 jsp file >> So you have to make each jsp file for one page(screen))

Ajax

Without form tag, let the web page works.
Short and streamlined codes like Jquery.

🍭 With form tag (no Ajax) .jsp

<form method="get" action="MethodServlet">
	<table>
   <tr><td align=right>ID</td><td><input type=text name=userid size=12></td>
   <tr><td align=right>PW</td><td><input type=text name=passwd size=12></td></tr>
   </table>
  <input type=submit value=submit>
   </form>

🍪 With Ajax .jsp

<table>
   <tr><td align=right>ID</td><td><input type=text name=userid size=12></td>
   <tr><td align=right>PW</td><td><input type=text name=passwd size=12></td>
   </tr></table>
   <input type="button" id=btnLogin value=login>
	</body>
	
	<script src="http://code.jquery.com/jquery-3.5.0.js"></script>
	<script>
	$(document)
	.on('click','#btnLogin',function(){
		$.ajax({
			url:'MethodServlet',
			method:'get',
			data:'userid='+$('input[name=userid]').val()
			+'&passwd='+$('input[name=passwd]').val(),
			dataType:'text',
			beforeSend:function(){},
			success:function(txt){
				alert(txt);
			},
			comelete:function(){
				
			}
		})

same code for both of them(form and ajax)

package web02;

import java.io.IOException;
import java.io.PrintWriter;

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 MethodServlet
 */
@WebServlet("/MethodServlet")
public class MethodServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public MethodServlet() {
        super();
        // TODO Auto-generated constructor stub
    }
	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");
		response.setContentType("text/html; charset=utf-8");
		PrintWriter out=response.getWriter();
		
		String userid=request.getParameter("userid");
		String passwd=request.getParameter("passwd");
		out.println("userid : "+userid+", password : "+passwd);
		out.close();
	}
}

result

📌 Compare form tag and ajax

1️⃣ Servlet and Method
🍭 form tag : <form method="get" action="MethodServlet">
🍪 ajax : url : 'MethodServlet', method : 'get'

2️⃣ Print data

🍭 form tag
Get data in .jsp and send it to .java. Then print in the java.

🍪 ajax
data:'userid='+$('input[name=userid]').val() +'&passwd='+$('input[name=passwd]').val()
dataType:'text'

Get data in .jsp and send it to .java. Then print in the java.

3️⃣ Submit(form) and Button(ajax)
🍭
When submit clicks, move to another file(jsp or java). And in the file(second), the next process works.
🍪
When button clicks, the next process works on the $(document)

4️⃣ Conclusion
Using ajax, web server calls a specific survlet in $(document). Like class instance of Java.

Kim

이전 포스트

Nov 11 : form tag

다음 포스트

Nov 12 :

JSP

📌 built-in objects

⛄ test code

📌 Attribute

📌 JSP action tag

Backend frameworks

Framework

Ajax

📌 Compare form tag and ajax

Nov 11 : form tag

Nov 13

0개의 댓글

관련 채용 정보

Nov 12 :

JSP

📌 built-in objects

⛄ test code

📌 Sign in and login (all jsp files) with REQUEST and RESPONSE

📌 Attribute

📌 JSP action tag

Cookie and Session

Backend frameworks

Framework

Ajax

📌 Compare form tag and ajax

Nov 11 : form tag

Nov 13

0개의 댓글

관련 채용 정보