分页功能学习笔记(Struts2+jsp)

这里的分页主要用到了jstl标签,
框架是struts2


个人在做的过程中犯过的错误：
在Action中忘记写totalPage的get和set方法，导致jsp接收不到数据没显示.

个人认为在不理解的时候看图理解流程思路清晰后更好。

下面是图和部分主要代码(老师的)：
代码写的顺序：DAO->Action->jsp

//DAO:public class CostDAOImpl implements ICostDAO{public List<Cost> findAll() throws DAOException {List<Cost> list = new ArrayList<Cost>();String sql = "select * from COST";Connection con = DBUtil.getConnection();try {PreparedStatement ps = con.prepareStatement(sql);ResultSet rs = ps.executeQuery();while(rs.next()){Cost c = createCost(rs);list.add(c);}} catch (SQLException e) {e.printStackTrace();throw new DAOException("查询全部资费数据失败!", e);}finally{DBUtil.close(con);}return list;}private Cost createCost(ResultSet rs) throws SQLException{Cost c = new Cost();c.setId(rs.getInt("id"));c.setName(rs.getString("name"));c.setBaseDuration(rs.getInt("base_duration"));c.setBaseCost(rs.getDouble("base_cost"));c.setUnitCost(rs.getDouble("unit_cost"));c.setStatus(rs.getString("status"));c.setDescr(rs.getString("descr"));c.setCreateTime(rs.getDate("creatime"));c.setStartTime(rs.getDate("startime"));c.setCostType(rs.getString("cost_type"));return c;}public List<Cost> findByPage(Integer page, Integer pageSize)throws DAOException {List<Cost> list = new ArrayList<Cost>();String sql = "select * from (" +" select c.*, rownum r from cost c" +") where r>? and r<?";Connection con = DBUtil.getConnection();try {PreparedStatement ps = con.prepareStatement(sql);//小于下一页的最小行int nextMin = page*pageSize + 1;//大于上一页的最大行int lastMax = (page-1)*pageSize;ps.setInt(1, lastMax);ps.setInt(2, nextMin);ResultSet rs = ps.executeQuery();while(rs.next()){Cost c = createCost(rs);list.add(c);}} catch (SQLException e) {e.printStackTrace();throw new DAOException("分页查询资费数据失败!", e);}return list;}public Integer findTotalpage(Integer pageSize) throws DAOException {//查询总行数String sql = "select count(*) from cost";Connection con = DBUtil.getConnection();try {PreparedStatement ps = con.prepareStatement(sql);ResultSet rs = ps.executeQuery();if(rs.next()){//根据总行数计算总页数int rows = rs.getInt(1);if(rows%pageSize == 0){return rows/pageSize;}else{return rows/pageSize + 1;}}} catch (SQLException e) {e.printStackTrace();throw new DAOException("查询总行数失败", e);}finally{DBUtil.close(con);}return 0;}}

//Action:public class FindCostAction {//页容量，默认为5private Integer pageSize = 5;//input//页码默认为1private Integer page = 1;//outputprivate List<Cost> costs;private Integer totalPage;/* * 业务方法查询每一页的数据 */public String execute(){ICostDAO dao = DAOFactory.getCostDAO();try {costs = dao.findByPage(page, pageSize);totalPage = dao.findTotalpage(pageSize);} catch (DAOException e) {e.printStackTrace();return "error";}return "success";}public List<Cost> getCosts() {return costs;}public void setCosts(List<Cost> costs) {this.costs = costs;}public Integer getPageSize() {return pageSize;}public void setPageSize(Integer pageSize) {this.pageSize = pageSize;}public Integer getPage() {return page;}public void setPage(Integer page) {this.page = page;}public Integer getTotalPage() {return totalPage;}public void setTotalPage(Integer totalPage) {this.totalPage = totalPage;}}

Jsp:

<c:choose>                <c:when test="${page==1 }">                <a href="#">上一页</a>                </c:when>                <c:otherwise>                <a href="findCost?page=${page-1 }">上一页</a>                </c:otherwise>                </c:choose>                                    <c:forEach begin="1" end="${totalPage}" var="k">                    <c:choose>                    <c:when test="${k==page }">                    <!-- 当连接的地址和浏览器中URL的namespace一致时,namespace及其之前                    的内容可以省略，这是相对路径的写法 -->                    <a href="findCost?page=${k }" class="current_page">${k }</a>                    </c:when>                    <c:otherwise>                    <a href="findCost?page=${k }">${k }</a>                    </c:otherwise>                    </c:choose>                    </c:forEach>                                        <c:choose>                    <c:when test="totalPage">                    <a href="#">下一页</a>                    </c:when>                    <c:otherwise>                    <a href="findCost?page=${page+1 }">下一页</a>                    </c:otherwise>                    </c:choose>

用OGNL表达式写的Jsp:

注意加标签库

<%@taglib uri="/struts-tags" prefix="s"%>                       <s:iterator value="costs">                                   <tr>                            <td><s:property value="id"/></td>                            <td><a href="fee_detail.html"><s:property value="name"/></a></td>                            <td><s:property value="baseDuration"/></td>                            <td><s:property value="baseCost"/></td>                            <td><s:property value="unitCost"/></td>                            <td><s:property value="createTime"/></td>                            <td><s:property value="startTime"/></td>                            <td><s:if test="status==0">开通</s:if><s:else>暂停</s:else></td>                            <td>                                                                <input type="button" value="启用" class="btn_start" onclick="startFee();" />                                <input type="button" value="修改" class="btn_modify" onclick="location.href='fee_modi.html';" />                                <input type="button" value="删除" class="btn_delete" onclick="deleteFee();" />                            </td>                        </tr>                        </s:iterator>                    <s:if test="page==1"><a href="#">上一页</a></s:if>                <s:else>                <a href="findCost?page=<s:property value="page-1"/>">上一页</a>                </s:else>                                    <s:iterator begin="1" end="totalPage" var="k">                    <s:if test="page==#k"><a href="findCost?page=<s:property value="#k"/>" class="current_page">                    <s:property value="#k"/></a></s:if>                    <s:else><a href="findCost?page=<s:property value="#k"/>"><s:property value="#k"/></a></s:else>                    </s:iterator>                                        <s:if test="page==totalPage"><a href="#">下一页</a></s:if>                    <s:else><a href="findCost?page=<s:property value="page+1"/>">下一页</a></s:else>