MyBatis基于pagehelper实现分页原理及代码实例

<!-- https://mvnrepository.com/artifact/com.github.pagehelper/pagehelper -->
<dependency>
  <groupId>com.github.pagehelper</groupId>
  <artifactId>pagehelper</artifactId>
  <version>5.1.11</version>
</dependency>

　　　<plugins>
    <plugin interceptor="com.github.pagehelper.PageInterceptor"></plugin>
  </plugins>

private void selectAllUsers(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
  {

    String num=request.getParameter("num");

    if(null==num)
    {
      num="1";
    }

    // Page PageInfo

    Page<?> page=PageHelper.startPage(Integer.parseInt(num),5); //设置第几条记录开始，多少条记录为一页

    //通过userService获取user的信息，其sql语句为"select * from user" 但因pagehelp已经注册为插件，所以pagehelp会在原sql语句上增加limit，从而实现分页
    List<Person> persons=userService.getAllUsersBypageHelper(); //因而获得的是分好页的结果集
     
    PageInfo<?> pageHelper=page.toPageInfo(); //获取页面信息的对象，里面封装了许多页面的信息 如：总条数，当前页码，需显示的导航页等等

    request.setAttribute("persons",persons);
    request.setAttribute("pagehelper",pageHelper);

    request.getRequestDispatcher("/persons.jsp").forward(request,response);

  }