前面写了Servlet（一）到（五），主要是在网上搜罗的视频、对分页这块还是不太清楚。于是有找到一些视频，重新学习了一下。主要是对分页的认识和设计思路。也是为了方便我以后回忆一下。。
一、分页常识
pageSize //每页有多少条记录 --用户设定
rowCount //一共有多少条记录 --从数据库中查的
pageIndex //当前查看的是第几页 --用户选择的
beginRow //从第几行开始查询 --计算得到 pageSize*(pageIndex-1)
pageCount //总共有多少页 --计算
//栗子 if(rowCount%pageSize==0){ pageCount=rowCount/pageSize; } else{ pageCount=rowCount/pageSize+1 }
二、PageInfo 类
public class PageInfo { private int pageSize; // 页面大小 private int pageCount; // 页面总数 private int pageIndex; // 当前页 private int beginRow; // 开始页 private int rowCount; // 总条数 private boolean hasNext; // 是否有后一页 private boolean hasPre; // 是否有前一页 public int getPageSize() { return pageSize; } public void setPageSize(int pageSize) { this.pageSize = pageSize; } public int getPageCount() { return pageCount; } public void setPageCount(int pageCount) { this.pageCount = pageCount; } public int getPageIndex() { return pageIndex; } public void setPageIndex(int pageIndex) { this.pageIndex = pageIndex; } public int getBeginRow() { return beginRow; } public void setBeginRow(int beginRow) { this.beginRow = beginRow; } public int getRowCount() { return rowCount; } public void setRowCount(int rowCount) { this.rowCount = rowCount; } public boolean isHasNext() { return hasNext; } public void setHasNext(boolean hasNext) { this.hasNext = hasNext; } public boolean isHasPre() { return hasPre; } public void setHasPre(boolean hasPre) { this.hasPre = hasPre; } }
三、分页工具类
public class PageUtil { public static PageInfo getPageInfo(int pageSize, int rowCount, int pageIndex) { PageInfo p=new PageInfo(); pageSize=getPageSize(pageSize); p.setPageSize(pageSize); p.setRowCount(rowCount); p.setPageCount(getPageCount(pageSize,rowCount)); p.setBeginRow(getBeginRow(pageSize,pageIndex)); p.setHasNext(isHasNext(pageIndex,getPageCount(pageSize,rowCount))); p.setHasPre(isHasPre(pageIndex)); p.setPageIndex(pageIndex); return p; } //判断当是否有前一页 private static boolean isHasPre(int pageIndex) { if(pageIndex==1){ return false; } else { return true; } } //判断是不是有下一页 private static boolean isHasNext(int pageIndex, int pageCount) { if(pageIndex==pageCount||pageCount==0){ return false; } else{ return true; } } //计算从第几行开始查询 private static int getBeginRow(int pageSize, int pageIndex) { return pageSize*(pageIndex-1); } //计算页的总数 private static int getPageCount(int pageSize, int rowCount) { if(rowCount%pageSize==0){ return rowCount/pageSize; } else{ return rowCount/pageSize+1; } } //返回pageSize private static int getPageSize(int pageSize) { return pageSize==0?10:pageSize; } }
四、页面
<script type="text/javascript"> function subForm(){ //form1.action="AdminServlet?flag=manage"; form1.submit(); } </script> <body> <form action ="AdminServlet" method="post" name="form1"> <input type="hidden" name=flag value="manage" /> <table width=80% border=1 cellspacing=0s> <c:forEach var="u" items="${adminList}"> <tr> <td>${u.id }</td> <td>${u.userName }</td> <td>${u.password }</td> <td>${u.note }</td> <td><a href="admin/admin_edit.jsp?id=${u.id }" >修改</a> | <a onclick="return confirm('确定要删除吗?')"
href="AdminServlet?flag=del&id=${u.id }" >删除</a></td> </tr> </c:forEach> </table> 共有 ${ pageInfo.rowCount} 条记录，当前第 ${ pageInfo.pageIndex} 页， 共 ${ pageInfo.pageCount}页 <c:choose> <c:when test="${pageInfo.hasPre }"> <a href="AdminServlet?flag=manage&pageIndex=1" >首页</a>
<a href="AdminServlet?flag=manage&pageIndex=${pageInfo.pageIndex-1 }" >前一页 </a> </c:when> <c:otherwise> 首页 前一页 </c:otherwise> </c:choose> <c:choose> <c:when test="${pageInfo.hasNext }"> <a href="AdminServlet?flag=manage&pageIndex=${pageInfo.pageIndex+1 }" >下一页</a>
<a href="AdminServlet?flag=manage&pageIndex=${pageInfo.pageCount }" >尾页 </a> </c:when> <c:otherwise> 下一页 尾页 </c:otherwise> </c:choose> <a href="javascript:subForm()" >转到</a> 第 <input type="text" name="pageIndex" value=${pageInfo.pageIndex }> 页 </form>
五、控制层
private void manage(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { int pageSize=4; int rowCount=_dao.getUserCount(); String pageIndexStr=request.getParameter("pageIndex"); int pageIndex=1; if(!StrUtil.isNullOrEmpty(pageIndexStr)){ pageIndex=Integer.parseInt(pageIndexStr); } PageInfo pageInfo=PageUtil.getPageInfo(pageSize,rowCount,pageIndex); List<UserInfo> adminList=_dao.getUserList(pageInfo); request.setAttribute("adminList", adminList); request.setAttribute("pageInfo", pageInfo); request.getRequestDispatcher("/admin/admin_manage.jsp").forward(request, response); }