Page number logic and reference code (java)

■ Table of contents 1, at the beginning 2, page number logic 3, code example

■ Introduction When I made a search site, I took a lot of time to display the page number, so I will post it thought. I would appreciate it if you could refer to it. (Since it is an example, please let me know if there is an improvement or better code)

■ Page number logic

When the page is 1, the numbers up to 5 are displayed, and "..." is displayed in between to display the last number.

When the page number is 5 or more, the first page, the front two page numbers, the back two, and the last number are displayed.

If the page is (last page-3), the first page, the last page, and the previous page are displayed.

■ Code example (jsp) The href of the a tag is the code without the link. Since there is no sense in naming variables and constants, please let me know if you have a good name.

<%
//Number of pages / Variable declaration of current page
int currentPage;
int lastPageNum;
//Variable assignment
currentPage = 5;
lastPageNum = 9;
//Constant declaration
final int FIRST_PAGE = 1;
final int FIRST_HALF_CHECK = 5;
final int LAST_HALF_CHECK = 4;
final int BEFORE_AND_AFTER = 2;
%>

<section>
<div class="pageLeft">
<%if(currentPage != FIRST_PAGE){ %>
<a href="">To the previous page</a>
<%} %>
</div>
<div class="pageCenter">
<%if(currentPage >= FIRST_HALF_CHECK){ %>
<a href="">1</a>
…
<%} %>
<%if(currentPage < FIRST_HALF_CHECK){ %>
	<%for(int i = 1; i <= FIRST_HALF_CHECK; i++){ %>
		<%if(i <= lastPageNum){ %>
		//Branch whether to include a tag or not (currently page does not include a tag)
			<%if(i == currentPage){ %>
				<span><%=i %></span>
			<%}else{ %>
				<a href=""><%=i %></a>
			<%} %>
		<%} %>
	<%} %>
<%}else if(lastPageNum - currentPage < LAST_HALF_CHECK){ %>
	<%for(int i = lastPageNum - LAST_HALF_CHECK; i <= lastPageNum; i++){ %>
		<%if(i > 0){ %>
		//Branch whether to include a tag or not (currently page does not include a tag)
			<%if(i == currentPage){ %>
				<span><%=i %></span>
			<%}else{ %>
				<a href=""><%=i %></a>
			<%} %>
		<%} %>
	<%} %>
<%}else{ %>
	<%for(int i = currentPage - BEFORE_AND_AFTER; i <= currentPage + BEFORE_AND_AFTER; i++){ %>
		//Branch whether to include a tag or not (currently page does not include a tag)
		<%if(i == currentPage){ %>
			<span><%=i %></span>
		<%}else{ %>
			<a href=""><%=i %></a>
		<%} %>
	<%} %>
<%} %>
<%if(lastPageNum - currentPage >= LAST_HALF_CHECK){ %>
	…<a href=""><%=lastPageNum %></a>
<%} %>
</div>
<div class="pageRight">
<%if(currentPage != lastPageNum){ %>
	<a href="">to the next page</a>
<%} %>
</div>
</section>

■ Summary I wrote it because I got stuck in page number logic once on the search site. I think there are better ways and improvements, so I would appreciate it if you could let me know.