Web分页技术

首先是DAO层

根据页数查询所有记录,返回List集合

/** * 根据页数查询所有记录,返回List集合 * @param page * @return */
    public static List<Blog> getBlogsByPage(int page){
        List<Blog> list = null;
        try {
            list = (List) qr.query(conn, "SELECT * FROM blog limit ?,3", new BeanListHandler(Blog.class),(page-1)*3);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
        return list;
    }

返回行数

/** * 返回行数 * @return */
    public static int getLimit(){
        Map<String, Object> map = null;
        try {
            map = qr.query(conn, "select count(*) from blog", new MapHandler());
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
        long i = (Long) map.entrySet().iterator().next().getValue();
        int limit = (int) i;
        return limit;
    }

JSP部分

 <table>
        <thead>
            <tr>
                <th>用户</th><th>标题</th><th>内容</th><th>发布时间</th>
            </tr>
        </thead>
        <tbody>
            <!-- 根据从DAO中查询到的集合遍历记录 -->
            <c:forEach items="${requestScope.blogs }" var="blog">
                <tr>
                    <td>${blog.username }</td>
                    <td>${blog.title }</td>
                    <td>${blog.content }</td>
                    <td>${blog.time }</td>
                </tr>
            </c:forEach>
            <tr>
                <!-- 请求中带有page参数,代表页数 -->
                <td><a href="${pageContext.request.contextPath}/Blogs/blogs?page=1">首页</a></td>
                <td><a href="${pageContext.request.contextPath}/Blogs/blogs?page=${page-1}">上一页</a></td>
                <td><a href="${pageContext.request.contextPath}/Blogs/blogs?page=${page+1}">下一页</a></td>
                <td><a href="${pageContext.request.contextPath}/Blogs/blogs?page=${last}">末页</a></td>
            </tr>
        </tbody>
    </table>

WEB后台处理部分

@Controller
@RequestMapping("Blogs")
public class Blogs {
    @RequestMapping("blogs")
    public String blogs(HttpServletRequest request , HttpServletResponse response,String page){
        int paging;
        //末页
        int last;
        //获取数据库总记录数
        int limit = BlogDao.getLimit();
        //设置末页
        int i = limit%3;
        if(i==0){
            last = limit/3;
        }else{
            last = (limit/3)+1;
        }

        //判断请求参数page(当前页)
        if(page==null||"".equals(page)){
            //如果是第一次访问,页数设置为第一页
            paging = 1;
        }else{
            //不是第一次访问,获取页数
            paging = Integer.parseInt(page);
            //如果当前页小于1,页数设置为1
            if(paging<=1){
                paging = 1;
            }
            //如果当前页大于末页,页数设置为末页
            if(paging>=last){
                paging = last;
            }

        } 
        //查询记录
        List<Blog> list = BlogDao.getBlogsByPage(paging);
        //存储记录,当前页,末页
        request.setAttribute("blogs", list);
        request.setAttribute("page", paging);
        request.setAttribute("last", last);
        return "jsp/blogs";
    }


}