Expression Language (EL) in JSP

The following article describes the Expression Language (EL) in JSP.

Expression Language (EL) is a scripting language used in JSP to simplify the process of accessing and manipulating data within a JSP page. It provides a simple and intuitive syntax for accessing properties and methods of Java objects, as well as other types of data such as request parameters, session attributes, and application-scoped variables.

In JSP, EL expressions are enclosed in ${ and } tags. The syntax of an EL expression is similar to that of a Java expression, but with some differences. For example, EL expressions use dot notation to access the properties of an object, as opposed to the traditional Java syntax of using the dot operator followed by the property name.

The following code shows an example of an EL expression that retrieves a request parameter named “username” and displays it on the page.

<p>Welcome, ${param.username}!</p>

In this example, the EL expression uses the param implicit object to access the value of the “username” parameter passed in the HTTP request.

EL also provides a range of operators and functions that can be used to manipulate data. For example, the following EL expression calculates the sum of two numbers.

${5 + 7}

EL also supports conditional statements and iteration, allowing developers to write more complex expressions. For example, the following EL expression displays a list of names retrieved from an ArrayList.

<ul>
<c:forEachvar="name" items="${names}">
<li>${name}</li>
</c:forEach>
</ul>

In this example, the EL expression uses the forEach tag from the JSTL (JavaServer Pages Standard Tag Library) to iterate over an ArrayList named “names” and display each element in an HTML list item.

Overall, Expression Language provides a simpler and more concise way of accessing and manipulating data within a JSP page, and can make the code easier to read and maintain.

Further Reading