Implementing pagination functionality using displaytag

Displaytag is an open source tag library used for displaying and paginating data in JSP pages. It offers a set of tags that make it easier to display data from backend Java objects on frontend pages, and supports pagination of the data.

To implement pagination, follow these steps:

1. Introduce Displaytag library: To include Displaytag in a web project, you can add the Jar file which can be downloaded from the official website.
2. Include tag library declaration: Add the following tag library declaration at the top of the JSP page:
3. <%@ directive taglib uri="http://displaytag.sf.net" prefix="display" %>
4. Set data source: Retrieve data in the backend Java code and format it as needed by Displaytag. This can be done by creating a List object and adding the data to the List.
5. Using the display tag in a JSP page: Use the display tag to show data on a JSP page and enable pagination.
6. 
   
   
   
   
   

   Displaying Data
   

7. The name attribute specifies the data list to be displayed, here EL expression ${dataList} is used, which will retrieve data from the backend.
8. The pagesize property specifies the number of records displayed per page.
9. The requestURI attribute specifies the URL of the Servlet or JSP page that handles the pagination request.
10. Retrieve the page number parameter in the paginated Servlet or JSP page, and fetch the corresponding data from the data source as needed.
11. Convert the “page” parameter to an integer and assign it to the variable page.
    Convert the “pagesize” parameter to an integer and assign it to the variable pageSize.
    Calculate the startIndex by subtracting 1 from the page and multiplying it by pageSize.
    Retrieve data from the data source between startIndex and startIndex + pageSize, then set the data to the request.

In this way, pagination functionality can be achieved using Displaytag. By setting the appropriate data source and configuring pagination parameters, Displaytag can automatically handle pagination requests and display the corresponding data.