Where in a compiled servlet do various parts of a JSP file go?

Question

Before the translation phase, there was a <%! .... %> code line in my JSP page. I know that this would be run only once in the translated servlet. Does it mean that the servlet engine puts the code in the init() method in the servlet?

What I want to learn is: which kinds of code go to which methods after translation?

Thanks in advance.

OK, what if <% ........ %>?, we know that it run during each client access the servlet. it looks like that this would be installed in service method ? — Erdal76t, Mar 17 '13 at 16:42
You know you can look at the compiled servlet source, right? — Dave Newton, Mar 17 '13 at 17:30
@Erdal76t Has any answer solved your problem? If so, you can mark it as answer by clicking the `v` mark left of the answer. — Uooo, Apr 03 '13 at 04:28

Uooo · Accepted Answer · 2013-07-02T07:32:13.320

5

Here is an example:

This JSP code:

<%@ page import="java.util.*" %> <!-- 1 -->
<%! private Date date; %>        <!-- 2 -->
<% date = new Date(); %>         <!-- 3 -->
Current date: <%= date %>        <!-- 4 -->

Will get translated to:

import java.util.*; // 1

public class ServletAbc extends GenericServlet {

    private Date date; // 2

    public void service(ServletRequest request,ServletResponse response)
                throws IOException,ServletException{

        PrintWriter out=response.getWriter();

        date = new Date(); // 3

        out.println("Current date: "); // 4
        out.println(date);
    }
}

Note that minor parts of the translation are container-depended. E.g. the out.println() statements might be translated to out.println("Current date: " + date); as well.

edited Jul 02 '13 at 07:32

answered Mar 18 '13 at 13:30

Uooo

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would the class level parameters be private all the times? – Erdal76t Mar 18 '13 at 13:38
@Erdal76t sorry forgot the `private` keyword in the JSP. The code inside `<%! ... %>` will be inserted as is on class level. You can also declare static variables and methods there. – Uooo Mar 18 '13 at 13:43

Sagar Dalvi · Answer 2 · 2013-03-18T13:01:33.977

2

At the time of code compilation code containing inside <%! .... %> this tag is consider as class member of servlet.

and

code containing inside <% .... %> this tag goes into the service() method of servlet.

If you want to see the generated java file, go to tomcat/work/..... directory.

File will be created with name as JspFileName_jsp.java and JspFileName_jsp.class

For better understandings visit this link

edited Mar 18 '13 at 13:01

answered Mar 18 '13 at 12:55

Sagar Dalvi

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Where in a compiled servlet do various parts of a JSP file go?

2 Answers2

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