2018-03-04 web用户项目(三):实现用户信息分页查询

2018-03-04 本文已影响0人紫杉叶子

笔记如下

思路:
1.每一页里有十条记录,每页就是一个PageBean,封装了总记录数,当前是第几页,每页条数,当前是第几页的数据

2018-03-01_214242.png

2.两个公式

2018-03-01_214242.png

*jsp

<body>
    <c:if test="${empty pageBean.customers}">
        当前页没有数据
    </c:if>
    <c:if test="${not empty pageBean.customers}">
        <h3 style="text-align: center; ">当前是${pageBean.pageNum}页数据</h3>
        <table border="1" width="100%"> 
            <tr>
                <th>客户姓名</th>
                <th>客户性别</th>
                <th>客户生日</th>
                <th>客户邮箱</th>
                <th>客户手机</th>
                <th>客户爱好</th>
                <th>客户类型</th>
                <th>客户描述</th>
            </tr>
            <c:forEach items="${pageBean.customers}" var="customer">
                <tr>
                    
                    <td>${customer.name}</td>
                    <td>${customer.gender}</td>
                    <td>${customer.birthday}</td>
                    <td>${customer.email}</td>
                    <td>${customer.cellphone}</td>
                    <td>${customer.preference}</td>
                    <td>${customer.type}</td>
                    <td>${customer.description}</td>
                </tr>
            
            </c:forEach>
        </table>
        <br/>
        <div style="text-align: center; ">
            <c:if test="${pageBean.pageNum != 1 }">
                <a href="${pageContext.request.contextPath}/pagequery?pagenum=1">首页</a> 
                <a  href="${pageContext.request.contextPath}/pagequery?pagenum=${pageBean.pageNum-1}">上一页</a> 
            </c:if>
            <!-- 参考百度左五右四 -->
            <c:forEach begin="${pageBean.pageNum-5>0?pageBean.pageNum-5:1}" end="${pageBean.pageNum+4<pageBean.totalPageNum?pageBean.pageNum+4:pageBean.totalPageNum}" var="i">
                <c:if test="${pageBean.pageNum == i}">
                    <font color="red">${i}</font>
                </c:if><c:if test="${pageBean.pageNum != i}">
                    
                    <a href="${pageContext.request.contextPath}/pagequery?pagenum=${i}">${i}</a>
                </c:if>
            
            </c:forEach>
            
            <c:if test="${pageBean.pageNum != pageBean.totalPageNum }">
                <a  href="${pageContext.request.contextPath}/pagequery?pagenum=${pageBean.pageNum+1}">下一页</a> 
                <a href="${pageContext.request.contextPath}/pagequery?pagenum=${pageBean.totalPageNum}">尾页</a> 
            </c:if>
        </div>
        
    </c:if>
    
</body>

web层(PageQueryServlet.java)

//拿到需要看到页是那一页
        String pagenum = request.getParameter("pagenum");
        
        //调用业务层去查询目标页的数据
        CustomerService cs = new CustomerService();
        
        //返回当前页的目标数据是不够的,还要做导航条
        //为了做分页,需要引入一个新的javaBean
        PageBean pageBean =  cs.pageQuery(pagenum);
        
        //将pagebean存到request域中
        request.setAttribute("pageBean", pageBean);
        request.getRequestDispatcher("/bean.jsp").forward(request, response);

业务层(CustomerService.java)

//完成分页查询的业务方法:
    public PageBean pageQuery(String num) {
        
        int numberPerPage = 10;//默认每页十条
        
        int pageNum = Integer.parseInt(num);//当前页是那一页
        
          
          //从数据库里查找总记录数
        int totalRecordsCount = cdao.getToltalCount();
        
        //运用公式
        int totalPageNum = (totalRecordsCount + numberPerPage-1)/numberPerPage;//总页数
        
        //select * from customers limit ?,?
        int startIndex = (pageNum-1)*numberPerPage;

        //从数据库里查找10条记录
        List<Customer> customers = cdao.getCurrectPageData(startIndex,numberPerPage);
        
        //封装数据
        PageBean pageBean = new PageBean();
        pageBean.setNumberPerPage(numberPerPage);
        pageBean.setCustomers(customers);
        pageBean.setPageNum(pageNum);
        pageBean.setTotalPageNum(totalPageNum);
        pageBean.setTotalRecordsCount(totalRecordsCount);
        
        return pageBean;
    }

dao层(CustomerDaoImpl.java)

    //获得总记录条数
    @Override
    public int getToltalCount() {
        
        QueryRunner runner = new QueryRunner(JdbcUtils.getDataSource());
        
        try {
         long count =  (long) runner.query("select count(*) from customers", new ScalarHandler());
         return (int)count;
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
        
    }
    
    //查询目标页的数据返回
    @Override
    public List<Customer> getCurrectPageData(int startIndex, int numberPerPage) {
        
        QueryRunner runner = new QueryRunner(JdbcUtils.getDataSource());
        
        String sql = "select * from customers limit ?,?";
        try {
            return runner.query(sql, new BeanListHandler<Customer>(Customer.class),startIndex,numberPerPage);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
        
        
        
    }

实现效果:

4.png

2018-03-04 web用户项目(三):实现用户信息分页查询

笔记如下

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