>From: Hariharan N <[EMAIL PROTECTED]>
>Reply-To: A mailing list about Java Server Pages specification and
> reference <[EMAIL PROTECTED]>
>To: [EMAIL PROTECTED]
>Subject: Re: Executing SQL query in bean
>Date: Thu, 4 Jan 2001 07:54:51 -0800
>
>Hi!
> Are u sure the System.out.println will display the records in the JSP
>page, think we have to use the JSP printWriter implicit object "out" to
>display something in the JSP page.
No, the System.out.println() does not print anything in the jsp file. You
are right you need the out.println() instead. The use of the System... is
for informative reasons. I just put it there in order to show you how it
should be done. Actually the System.out would not print anything on the
screen (unless you have a main method defined) but all the output will go
into the default output files under the log directory of your JSP engine you
are using.
>Now this gives rise to..
>1. Suppose we want to display something from a bean like System.out.println
>in the JSP page,
>do we have to pass the implicit out object to the bean or which way?
>can we invoke a method say.. write() in the JSP page from a bean??
If you want to display the records you can declare the method of type
String (or Vector or ResultSet or anything you want) and return a specific
value. Then call this method from inside the jsp file and all the data you
want will be displayed in the jsp page. For example you can have.
public void String printThis()
{
return "hello from printThis";
}
Inside the jsp you can have (if assume the reference to the class is myRef)
out.println(myRef.printThis());
This will print the "hello from printThis".
>a jdbc question too..
>what exactly is class.forName does....
It loads the appropriate database drivers. In order to make the database
to work you need the right drivers. The class.forName loads the proper
classes (which are the drivers for the database). Every database has
different drivers, so it depends on the database you are using what drivers
you need to load.
>
>
>At 03:15 AM 1/4/01 -0800, you wrote:
> > In the bean put all the relevant commands in order to open the
>connection
> >with the database. Lets say that you have a method called
> >
> >public void openConnection()
> >{
> > try
> > {
> > // Load the database's drivers.
> > Class.forName("database's drivers here");
> >
> > // Obtain connection with the database.
> > Connection dbcon = DriverManager.getConnection("databse address
> >here", "username here", "password here");
> >
> > // create new statemtn here.
> > Statement stmt = dbcon.createStatement();
> >
> > String select = "SELECT * FROM <table name here>";
> >
> > // get the whole result set
> > ResultSet rs = stmt.executeQuery(retrieve);
> >
> > // go through all rows
> > while (rs.next())
> > {
> > System.out.println(rs.toString());
> > }
> >
> > } // end try
> > // If driver not found.
> > catch (ClassNotFoundException cnfe)
> > {
> > System.out.println("Driver not found. " + cnfe);
> > }
> > catch (SQLException sqle)
> > {
> > System.out.println("Connection to the database could not be
>established.
> >" + sqle);
> > }
> >}
> >
> >Then define a bean in the jsp page using the <jsp:useBean> tag.
> >
> > Call the openConnection using the beans reference name (lets say that
>the
> >reference to the bean is called myBean) myBean.openConnection();
> >this will open the connection with the database and will display all the
> >data in the specified table.
> >
> > You can have two diffreent methods if you want. One to open the
> >copnnection and the other to get the data. You can call them with the
>same
> >way. Do not forget to close the connection with the databse after you
> >finish. Use the close() method in order to do it.
> >
> > Hope this helps.
> >
> >
> >
> >
> >>From: Deepak Kumar <[EMAIL PROTECTED]>
> >>Reply-To: A mailing list about Java Server Pages specification and
> >> reference <[EMAIL PROTECTED]>
> >>To: [EMAIL PROTECTED]
> >>Subject: Executing SQL query in bean
> >>Date: Thu, 4 Jan 2001 02:48:54 -0800
> >>
> >>Hi Friends,
> >>
> >>I want to write the code of JDBC connectivity in a
> >>bean and then use the resultset in JSP page how can i
> >>accomplish this.
> >>
> >>Thanks in advance.
> >>Deepak Kumar
> >>
> >>__________________________________________________
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> >>
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> >
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>
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