How to Extract URL Parameters in JSP Applications?

Extracting URL Parameters in JSP

Getting parameters from a URL can be crucial when handling user input or interacting with external systems in a JSP application. Here's how to retrieve URL parameters using the implicit objects provided by the Unified Expression Language (EL) or JSP Scriptlets.

Implicit Object Approach (EL)

According to the Java EE 5 Tutorial, JSP EL defines an implicit object, param, which maps request parameter names to their corresponding values. To access a parameter named "accountID" passed in the URL, you would use the following EL expression:

<code class="jsp">${param.accountID}</code>

JSP Scriptlet Approach (Not Recommended)

While still functional, JSP Scriptlets are no longer considered best practice. However, if you prefer this approach, you can retrieve the parameter using the request implicit object:

<code class="jsp"><%
    String accountId = request.getParameter("accountID");
%></code>

Example

For a URL like "www.somesite.com/Transaction_List.jsp?accountID=5," you can retrieve the "accountID" parameter as follows:

<code class="jsp">${param.accountID} // returns "5" using EL</code>

<code class="jsp"><%
    String accountId = request.getParameter("accountID");
    System.out.println(accountId); // prints "5" using JSP Scriptlets
%></code>

By leveraging these techniques, you can effectively extract parameters from URLs and utilize them in your JSP code.

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