Tutorials : : A very simple JSP-architecture Part 2

The view

Now for the view. We'll have to make a few changes here also to the simple view from my last article:

1. We need two input fields for customer name and address.
2. We need new buttons for update, delete and create.
3. Since we now have four functions, we'll have to insert the command name in the hidden form field when the user clicks one of the buttons. This can be done by some simple JavaScript, for example like this for the Search button:
   <input type=submit value="Search" onclick="myform.command.value='getdata'">
   

   If you do not want to use JavaScript, you can let the controller get the value of the Submit button, and use it to determine the command (remember to give all buttons the same name, as shown below).

The HTML in the view therefore looks like this:

<h3>CUSTOMER SEARCH</h3>

<b><%=cString(session.getValue("customerinfo.message"))%></b>

<form name=myform action="ctrlcustomerinfo.jsp" method=post>

Please enter the customer ID: 
<input type=text name=id value="<%=customer.getId()%>">

<input type=submit 
	name=sub 
	value="Search" 
	onclick="myform.command.value='getdata'">

<input type=submit 
	name=sub 
	value="Update" 
	onclick="myform.command.value='update'">

<input type=submit 
	name=sub 
	value="Delete" 
	onclick="myform.command.value='delete'">

<input type=submit 
	name=sub 
	value="Create" 
	onclick="myform.command.value='create'">

<input type=hidden 
	name=command 
	value="">

<br>

Name: 
	<input 
	type=text 
	name=name 
	value="
	<%=customer.getName()%>"><br>

Address: 
	<input 
	type=text 
	name=address 
	value="<%=customer.getAddress()%>"><br>

</form>

The source for the complete view is here: customerinfo.jsp. 

The Customer bean

In the Customer bean four new methods are added: isDataFound (see above), updateCustomer, deleteCustomer and createCustomer. You may view the source for the Customer bean and a helper class named Person, but note, that for simplicity no real database is used. Instead it's faked by keeping the customers (instances of class Person) in a Java Hashtable. This will work in our example, since the bean has scope "session", and data in the bean therefore is available for every request.

All files are also available in a zip-file.

Things like you might consider to add

1. When you update or create a customer you should probably check if the name and address has been filled in. This can be done with JavaScript in the browser, but to be safe you should also check in the controller--the user might have disabled JavaScript in his/her browser.
2. You would also want to check if the ID has been filled in (for all functions).

Conclusion

Even if the MVC-architecture presented is very simple, it will suffice for prototypes and a lot of smaller applications. The major advantage is rapid development, and since tasks (control, business logic, and presentation) are clearly separated, it's rather simple to expand and enhance the application.

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