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From "Zachary Mitchell, BCIS" <zac....@internode.on.net>
Subject Re: custom Table
Date Tue, 24 Feb 2009 03:44:39 GMT
There are a few things to do with JSP's

and copies of objects in JSP's,

when it comes to variables of

session and page

scopes.

A text/ebook like "special edition using Java 2 enterprise edition

clarifies this, but it all goes to the fact that  a jsp ends

by being compiled into a servlet, which is injected

 and then executed from there.

This means that every client run of the jsp

is running from THE SAME class of your programmed jsp,

though from different execution context instances.


You need to be careful that each page variable object

doesn't conflict with other objects by use of page objects.

You will want each copy of your resultset Object,

in each jsp page contextn, to be a unique object context, and have all of 
them,

ins your jsp, be dirty references back to your original copy.

It should, optmistically, be unbound from your resultSet Object produced by

bean/corba/rmi/ejb/whatever object source.

In your example, in a situation where each jsp page

may alter it's unique resultset object later on,

-you may use a to managelibrary class/bean/enterprise javaban

to have setResultSet/getResultSet methods.  These methods may have somethig 
like a linkedlist that holds resultsetl objects (or a complexresultset 
object of yous,

with field int field = 1;   with this reflected in get/set function 
signatures.

from hear, each page may the obtain it's own particular

pageContext copy of your resultselt object.

Or, you may use a linked list approach, getitng/setting methods,

on a LinkedList object in an application scope, which of its own, excludes 
the page context.

See how ya go, but doen't overlook the reading I suggested,

even though your stuck, and it's old!

:)




I recommend submitting your resultset




----- Original Message ----- 
From: "Thufir" <hawat.thufir@gmail.com>
To: <ecs-user@jakarta.apache.org>
Sent: Tuesday, February 24, 2009 1:23 PM
Subject: custom Table


>I think that the problem with this class is that setColumnNames and
> setData aren't really setting attributes.  I suppose I should make
> instance attributes like "header" and "data"?
>
> (luckily we're moving into JSP soon, but, still...)
>
> also, is there a problem with passing ResultSet around to different
> objects?  I read that there's a problem with that.
>
>
> package a00720398.html;
>
> //adapted from oreilly sample in ch 16
> //      Java Servlet Programming, Second Edition
> //         http://oreilly.com/catalog/9780596000400/
>
>
> import java.sql.*;
> import org.apache.ecs.html.*;
>
>
> public class ResultSetTable extends Table {
>
>    private static final boolean isPretty = true;
>    private ResultSet rst = null;
>    ResultSetMetaData rsmd = null;
>
>    public ResultSetTable() {
>    }
>
>    public ResultSetTable(ResultSet rst) throws SQLException {
>        this.rst = rst;
>        rsmd = rst.getMetaData();
>        setBorder(1);
>        setColumnNames();
>        setData();
>    }
>
>    public void setResultSet(ResultSet rst) throws SQLException {
>        this.rst = rst;
>        rsmd = rst.getMetaData();
>    }
>
>    private void setColumnNames() throws SQLException {
>        int colCount = rsmd.getColumnCount();
>        TR tr = new TR();
>        tr.setPrettyPrint(isPretty);
>
>        A a = new A();
>        a.setPrettyPrint(isPretty);
>        a.setHref("/Assignment?crud=D&row=0");
>        //<http://www.google.ca/search?q=doget
> +url&ie=utf-8&oe=utf-8&aq=t&rls=com.ubuntu:en-
> US:unofficial&client=firefox-a
>        a.addElement("delete");
>
>        TH colZero = new TH();
>        colZero.setPrettyPrint(isPretty);
>        colZero.addElement(a);
>        tr.addElement(colZero);
>
>        for (int i = 1; i <= colCount; i++) {
>            TH th = new TH();
>            th.setPrettyPrint(isPretty);
>            th.addElement(rsmd.getColumnLabel(i));
>            tr.addElement(th);
>        }
>        addElement(tr);
>    }
>
>    private void setData() throws SQLException {
>        int colCount = rsmd.getColumnCount();
>        TR tr = new TR();
>
>        //rst.beforeFirst();
>        while (rst.next()) {
>            tr = new TR();
>            tr.setPrettyPrint(isPretty);
>            for (int i = 1; i <= colCount; i++) {
>                TH th = new TH();
>                th.setPrettyPrint(isPretty);
>                th.addElement(rst.getString(i));
>                tr.addElement(th);
>            }
>            addElement(tr);
>        }
>    }
> }
>
>
>
> thanks,
>
> Thufir
>
>
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