JSP

Location: /WEB-INF/A.jsp
WEB-INF represents web app inner files, not expose to outside.
To prevent some jsp/html file on the server directly accessed by browsers from URL, we need to put all request sensitive jsp file under WEB-INF folder.
Put other jsp/html file outside WEB-INF, so browsers can directly access those files by URL.

Normally used forward action:
<jsp:forward page="/WEB-INF/login.jsp"></jsp:forward>

When the first time visiting jsp

1. web server will convert A.jsp to A_jsp.java
2. A_jsp.java will compile to A_jsp.class

So when the first time visit jsp, response time will be slow


9 objects

1. out
2. request
3. response
4. session
5. application   //servletContext
6. pageContext  //only this jsp scope
7. exception
8. page   //this
9. config   //servletConfig

3 syntax

Command

1. <%@ page
   contentType="text/html;charset=utf-8"
   language="java"
   import="java.util.*,java.net.*"
   pageEncoding="utf-8"
   session="true"
   buffer="none|8k|"
   autoFlash="true" //autoFlash to client when buffer full
   isThreadSafe = "true"
   errorPage="/error"
   isErrorPage="false"
   %>
   We can use more than one page tag to make page nicer
   <%@ page import="java.util.*" %>
   <%@ page import="java.net.*" %>
   
2. <%@ include file="a.jsp" %>  //static include
   //combine two jsp file to one servlet
3. taglib

Script

1. <% java code %>
2. <%=rs.getString("name")>  //output string, no ; at the end
3. <%! int count=10%>    //servlet scope, member variable
   <%  int count=10; %>    //function scope, local variable
   <%! public int test(String a){
       return a.length();
   }%>

Action

1. <jsp:forward page="/a.jsp"></jsp.forward>     //forward to page
   <jsp:forward page="/WEB-INF/login.jsp"></jsp:forward>
2. <jsp:include file=""></jsp:include>    //dynamic include
   //compile each jsp to different servlet first, then combine the output result

Comment

1. <!-- Comments -->  HTML comment, still output comment content
2. <%-- Comments --%>  JSP comment, does not output comment content to browser