mybatis 分页插件原理是什么样的？

Question

@RequestMapping(value = "/findAll",method = RequestMethod.GET) public String getUsers(){ int pageNum = 1; int pageSize = 10; PageHelper.startPage(pageNum, pageSize); List<User> list = userService.findAllUser(); PageInfo pageInfo = new PageInfo(list); Page page = (Page) list; return "PageInfo: " + JSON.toJSONString(pageInfo) + ", Page: " + JSON.toJSONString(page); } <select id="findAllUser" resultType="User"> SELECT * from users </select> PageInfo: {"endRow":10,"firstPage":1,"hasNextPage":true,"hasPreviousPage":false,"isFirstPage":true,"isLastPage":false,"lastPage":2,"list":[{"id":2,"name":"awbeci"},{"id":3,"name":"wulingmei"},{"id":4,"name":"qinxin"},{"id":5,"name":"qinxin2"},{"id":6,"name":"qinxin3"},{"id":7,"name":"???"},{"id":8,"name":"caochenglu"},{"id":10,"name":"sdfsdfs"},{"id":13,"name":"wangle"},{"id":14,"name":"react-cd-player"}],"navigateFirstPage":1,"navigateLastPage":2,"navigatePages":8,"navigatepageNums":[1,2],"nextPage":2,"pageNum":1,"pageSize":10,"pages":2,"prePage":0,"size":10,"startRow":1,"total":17}, Page: [{"id":2,"name":"awbeci"},{"id":3,"name":"wulingmei"},{"id":4,"name":"qinxin"},{"id":5,"name":"qinxin2"},{"id":6,"name":"qinxin3"},{"id":7,"name":"???"},{"id":8,"name":"caochenglu"},{"id":10,"name":"sdfsdfs"},{"id":13,"name":"wangle"},{"id":14,"name":"react-cd-player"}] 根据上面代码，确实可以分页了，但是我有点想不通：因为我的查询语句是select * from users，难道是我先从数据库中查询出所有数据，然后再在getUsers方法里面通过查询插件再进行分页？？？

Answer 1

看这个写法应该就是内存中分页了