Expression Language (EL)
The Expression Language (EL) is a faster/easier way to display parameter values. It is part of the JSP Specification. Expression Language is helpful for web designers. They may have limited Java knowledge yet still have the need to send and receive data from servlets or other Java objects. EL does this by encoding tags in the JSP. It is possible to use scriptlet tags <% and%> to accomplish the same task but EL simplifies this process.
Hello, ${param.visitor}
Same as
Hello, <%=request.getParameter("visitor")%>
EL offers a clearer way to navigate nested beans. Consider some beans:
class Person {
String name;
// Person nests an organization bean.
Organization organization;
public String getName() { return this.name; }
public Organization getOrganization() { return this.organization; }
}
class Organization {
String name;
public String getName() { return this.name; }
}
If an instance of Person was to be placed onto a request attribute under the name "person", the JSP would have:
Hello, ${person.name}, of company ${person.organization.name}
Same as.
Hello,
<% Person p = (Person) request.getAttribute("person");
if (p != null) {
out.print(p.getName());
}
%>, of company
<% if ((p != null) && (p.getOrganization() != null)) {
out.print(p.getOrganization().getName());
}
%>