Web Application Developer’s Guide phần 7 pptx

Tutorial: Creating a JSP with InternetBeans Express 13-7

Step 8: Adding the InternetBeans control tags

Step 8: Adding the InternetBeans control tags

Now it’s time to add the two control tags for the two text input fields. Add

the tags shown in bold.

<form method="POST">

<p>Enter your name:</p>

<ix:control dataSet="signatures" columnName="Name">

<input type="text" name="Name" size="50">

</ix:control>

<p>Enter your comment:</p>

<ix:control dataSet="signatures" columnName="Comment">

<input type="text" name="Comment" size="100">

</ix:control>

<p>

Note that you are wrapping each of the HTML text input tags in an

InternetBeans control tag. This allows the InternetBeans IxControls to

implicitly understand which text input fields they are replacing.

Step 9: Adding the InternetBeans submit tag

Add the opening and closing submit tags shown in bold.

<input type="text" name="Comment" size="100">

</ix:control>

<p>

<ix:submit methodName="submitPerformed">

<input type="submit" name="submit" value="Submit"></p>

</ix:submit>

</form>

Note that you are wrapping the HTML submit input tag in an

InternetBeans submit tag. This allows the InternetBeans IxSubmitButton to

implicitly understand which submit button it is replacing. We’re not done

with the submit button yet. You still have to add the method which will be

executed when the button is pushed. You’ll do that in the next step.

13-8 Web Application Developer ’ s Guide

Step 10: Adding the submitPerformed() method

Step 10: Adding the submitPerformed() method

Add the code shown in bold.

<ix:submit methodName="submitPerformed">

<%!

public void submitPerformed(PageContext pageContext){

DataSet signatures = (DataSet) pageContext.findAttribute( "signatures" );

signatures.post();

signatures.saveChanges();

}

%>

<input type="submit" name="submit" value="Submit"></p>

</ix:submit>

The submitPerformed() method is contained within a JSP declaration tag.

This method declaration doesn’t have to be nested within the

InternetBeans submit tag, but it is an elegant way of writing the code. The

parameter passed to this method is the PageContext. This is an object

containing information about the page, which exists for every JSP. The

method retrieves a DataExpress DataSet by finding the page attribute

corresponding to the “signatures” dataset. It then posts the user’s input to

the dataset, and saves the changes to the dataset.

Step 11: Adding code to insert a row

There is still one more piece of code you need to add before the JSP will

work properly. When the form is posted, you need to add an empty row

to the dataset to contain the user’s input. Add the code shown in bold.

</ix:table>

<%

signatures.insertRow(false);

%>

<form method="POST">

This last Java code fragment may look a little confusing, because it doesn’t

appear to be enclosed in a method declaration. It actually is. When the JSP

gets compiled this will become part of the service() method in the

generated servlet (which you can’t see, but it’s still there). Any line of code