Classic entry tutorial: JSP standard template library (below)

Classic entry tutorial: JSP standard template library (below)

JSTL tag library

JSTL is often considered a single tag library. But JSTL actually has 4 label libraries. These tag libraries are summarized as follows:

Core Tag Library - The necessary tags containing some web applications. Examples of the core label library include cyclic, expression assignments, and basic input output. Format / International Label - Includes label libraries that are used to parse data. This tag analyzes data, such as dates, different places, and more. Database Tag Library - contains labels that are used to access the SQL database. These tags typically only create prototype programs. This is because most programs do not process database access from the JSP page. Database access should be embedded in EJB that can be accessed by the JSP page. XML Tag Library - contains labels that are used to access the XML element. Because XML is widely used in Web development, XML processing is an important feature of JSTL.

In this article, we will only make a brief introduction to the core label. We will examine a simple example to explain how to handle the data entered in the form. Before we start checking the programs, we must first see how JSTL handles expressions, JSTL's expression processing is completed by using the EL expression language, only can be used in JSP2.0. In the next section, we will examine the EL expression language.

EL Expression Language

One of the main components of JSP2.0 is this new expression language called EL. EL is widely used in JSTL. However, it is important to remember that EL is the function of JSP instead of JSTL. The JSP Scriptlet code used in JSP 2.0 can include an EL expression. The following line code demonstrates the EL in the JSP Scriptlet code:

Your Total, Including Shipping IS $ {Total Shipping}

As you can see, Total and Shipping are added to generate HTML and display their values ​​in the browser. These expressions can also be used in the JSTL tag. An important issue for JSTL1.0 is that JSTL cannot be used on JSP1.2 versions. Because JSP1.2 does not support EL, there is a need to provide some additional JSTL tags to help EL use. For example, if you want to use JSTL to display the above expression, you can use the following code.

Your Total, Including Shipping IS

It is worth noting that JSTL does not require JSP 2.0 to run. This needs can be achieved by providing a label that can display an EL expression.

JSTL example

We will examine a simple example of using JSTL. In this example, we will examine a common process in web applications. We will see how to submit (POST) a form and process the result of the POST. The program code is as follows:

<% @ Taglib Uri = "http://java.sun.com/jstl/core" prefix = "c"%>