How to use Mybatis to achieve paging effect
This article mainly introduces how to use Mybatis to achieve paging effect, the article is very detailed, has a certain reference value, interested friends must read it!
First, create a paging tool class PageUti, which stores five pieces of data needed for paging: pageIndex (current page number), pageSize (number of records per page), count (total number of records), pageNum (total number of pages), list (content of each page).
/ * * @ param generic class * / public class PageUtil {/ / current page number private int pageIndex; / / records per page private int pageSize; / / total records private int count; / / total pages private int pageNum; / / content private List list; per page}
Second, xml files: MySQL supports paging through the limit clause.
Such as:
# 10 records per page. Take the first page and return the first 10 records
Select * from books limit (1-1) * 10pm 10
# 10 records per page, take the second page, return the 11th record, to the 20th record
Select * from books limit (2-1) * 10pm 10
So: the first parameter of limit = (current page number-1) * records per page
Select * from books limit # {pageIndex}, # {pageSize} select count (*) from books
Third, BooksServiceImpl.java: save the two parameters needed by limit into the map collection, and then encapsulate the five data needed for paging.
Public PageUtil getBooksPage (int pageIndex, int pageSize) {PageUtil pageUtil=new PageUtil (); SqlSession sqlSession= MybatisUtil.getSqlSession (); try {/ / booksMapper is a proxy object created by using dynamic proxy mode and running reflection mechanism, BooksMapper booksMapper=sqlSession.getMapper (BooksMapper.class); Map map=new HashMap (); int row=booksMapper.getCount (map) / / calculate the total number of pages int pageCount= (int) Math.ceil ((double) row / pageSize); / / the first parameter of limit = (current page number-1) * records per page map.put ("pageIndex", (pageIndex-1) * pageSize); map.put ("pageSize", pageSize); List list=booksMapper.getBooksPage (map) / / encapsulate data into pageUtil.setPageIndex (pageIndex); pageUtil.setPageSize (pageSize); pageUtil.setCount (row); pageUtil.setPageNum (pageCount); pageUtil.setList (list);} catch (Exception e) {e.printStackTrace ();} finally {sqlSession.close ();} return pageUtil }
4. Servlet:
Protected void getBooks (HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {if (request.getParameter ("pageIndex")! = null) {int pageIndex=Integer.parseInt (request.getParameter ("pageIndex")); show (response,pageIndex,search);} else {show (response);}} private void show (HttpServletResponse response,Object... ages) throws IOException {int pageIndex= 1 / / default first page if (ages.length > 0) {pageIndex= (int) ages [0];} PageUtil pageUtil=new PageUtil (); / / 10 pieces of data per page pageUtil=new BooksServiceImpl () .getBooksPage (pageIndex,10); String js= JSON.toJSONString (pageUtil); PrintWriter pw=response.getWriter (); pw.write (js);}
Fifth, the front page
Show pagination:
Var page = "total" + data.count + ", total" + data.pageNum + "page, current" + data.pageIndex + "page"; page + = "home page"; if (data.pageIndex = = 1) {page + = "previous page";} else {page + = "previous page";} / / for (var I = 1; I)
