javaWeb手动分页步骤

一：编写实体类
@Setter
@Getter
@ToString
@Entity
@Repository
public class PageBean<T> {
    private Integer currPage;//当前页
    private Integer pageSize;//每页条数
    private Integer totalCount;//总条数
    private Integer totalPage;//总页数
    private List<T> list;//当前页数据
}
二：编写dao层，写sql语句（mysql）

//查询总条数
    @Select("select count(1) from product")
    public Integer findByTotalCount();

    //分页查询
  @Select("select * from (SELECT *,(@rowNum:=@rowNum+1) as rowNo FROM product,(Select (@rowNum :=0) ) b) " +
          "res where rowNo>=#{param1} and rowNo<=#{param2}")
    List<Product> findByProduct(Integer start,Integer end);
三：编写service层以及实现类
1、service层

public PageBean<Product> findByProduct(Integer currPage, Integer pageSize);
2、实现类

@Override
public PageBean<Product> findByProduct(Integer currPage, Integer pageSize) {
   //1、创建PageBean对象
    PageBean<Product> pageBean = new PageBean<>();
    //2、获取当前页面（页面传参过来）
    pageBean.setCurrPage(currPage);
    //3、每页条数
    pageBean.setPageSize(pageSize);
    //4、总条数
    Integer totalCount = productDao.findByTotalCount();
    pageBean.setTotalCount(totalCount);
    //5、总页数
    double ceil = Math.ceil(totalCount * 1.0 / pageSize);
    pageBean.setTotalPage((int) ceil);
    //6、当前页面数据，从数据库查询
    int start = pageSize * (currPage - 1) + 1;
    int end = pageSize * currPage;
    List<Product> productList = productDao.findByProduct(start, end);
    pageBean.setList(productList);
    return pageBean;
}
四、编写控制器

//分页查询
@RequestMapping("/findByProduct")
public ModelAndView findByProduct(@RequestParam(value = "currPage",required = false,defaultValue = "1") Integer currPage,
             @RequestParam(value = "pagesSize",required = false,defaultValue = "5") Integer pageSize){
    PageBean<Product> pageBean = new PageBean<>();
    pageBean =productService.findByProduct(currPage, pageSize);
    ModelAndView modelAndView = new ModelAndView();
    modelAndView.addObject("pageBean",pageBean);
    modelAndView.setViewName("product-list");
    return modelAndView;
}
五、编写web网页文件

<div class="form-group form-inline">
   总共${pageBean.totalPage}页，共${pageBean.totalCount} 条数据。 每页
   <select class="form-control" id="pageSize" onchange="gotoPage(1)>

      <option value="2">2</option>
      <option value="3">3</option>
      <option value="5" selected="selected">5</option>
      <option value="10">10</option>
   </select> 条
</div>

<div class="box-tools pull-right">
   <ul class="pagination">
                       <%--在超链接中访问js函数 必须添加前缀 javascript--%>
      <li><a href="javascript:gotoPage(1)" aria-label="Previous">首页</a></li>
      <li><a href="javascript:gotoPage(${pageBean.currPage-1})">上一页</a></li>
                           <c:forEach begin="1" end="${pageBean.totalPage}" var="i">
                               <li><a href="javascript:gotoPage(${i})">${i}</a></li>
                           </c:forEach>
      <li><a href="javascript:gotoPage(${pageBean.currPage+1})">下一页</a></li>
      <li><a href="javascript:gotoPage(${pageBean.totalPage})" aria-label="Next">尾页</a></li>
   </ul>
</div>

<script type="text/javascript">
       $("#pageSize option[value=${pageBean.pageSize}]").prop("selected","selected");
       function gotoPage(currPage) {
           // 获取每页显示条数
           var pageSize = $("#pageSize").val();
           if(currPage<1){
               return;
           }
           if(currPage>${pageBean.totalPage}){
               return;
           }
           location.href="${pageContext.request.contextPath}/product/findByProduct?currPage="+currPage+"&pageSize="+pageSize

;
       }
</script>