I finally understood the JSP page.

When we query the database,If the query results are many,For example1000Entries,So,It would be intolerable if all of them are displayed on a page.!So we need to display it by page.,Display per page10Or20Line,The purpose of paging is as simple as this.

 

There are many paging Methods,It may be more efficient.,I can only refer to the simplest implementation method here.:How many records are queried,Then calculate the total number of pages,Each page is displayed..

Query the number of records:

Select count (*) from learning

 

Calculate the number of pages:

If (counts % pageSizes = 0) {pageCounts = counts/pageSizes ;}

Else {pageCounts = counts/pageSizes + 1 ;}

Int I = (intPage-1) * pageSizes ;(The algorithm in the book is stupid.,Use my own ideas here,No error)

The above is to determine whether the last page is full,