改写JSF 分页控件使其能支持大容量数据分页以及查询分页
?上一篇对分页的分页的封装是基于struts框架。如果要利用JSF组件实现类似的功能又该如何呢。我对JSF的痴迷始于半年以前，如今有所降温。当时对已有的分页组件作了较大的修改，并使其投入应用。?
对于JSF的学习我开始是看Core Java Server Faces和OReilly的一本Java Server Faces，个人觉得入门看前者是个不错的选择，本文关于分页组件的改写就基于Core Java Server Faces的一个分页组件的例子。
原例子是讲述JSF组件编写过程的好教材，但是其实用性不强，主要是：它把所有数据一次性的读入内存再进行分页，所以不支持大容量的分页；它不支持查询结果分页。
先贴上页面部分的代码：
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<%@ page language="java" contentType="text/html; charset=GBK"%> <%@ page import="com.inventec.cmm.QueryBean" %> <%@ taglib uri="http://java.sun.com/jsf/core" prefix="f" %> <%@ taglib uri="http://java.sun.com/jsf/html" prefix="h" %> <%@ taglib uri="http://corejsf.com/pager" prefix="corejsf" %> <html> <f:view> <font color="red"><h:outputText value="#{queryBean.msg}"/></font> <HEAD><TITLE >中獎用戶信息查詢</TITLE> <META http-equiv=Content-Type content="text/html; charset=gb2312"> <link rel="stylesheet" type="text/css" href="style.css"> <script language="JavaScript" src="calendar.js" Type="Text/JavaScript" charset="gb2312" ></script> <LINK href=style.css type=text/css rel=stylesheet> </HEAD> <BODY> <TABLE cellSpacing=0 cellPadding=0 align=center bgColor=#EAEFF3 border="datagrid" width=60%> <h:form id="frmQuery"> <TR align=middle > <TD bgColor=#2153aa colSpan=7 height=34> <DIV id=reg> <font color="#FFFFD1"><STRONG>中獎信息查詢</STRONG></font> </DIV></TD></TR> <TR> <Th align=middle height=12>開始時間</Th> <TD align=center><IMG height=1 src="pics/empty.gif" width=10><h:inputText id="DATE_BEGIN" value="#{queryBean.dateBegin}" onfocus="calendar()" /><IMG height=1 src="pics/empty.gif" width=10></TD> <Th align=middle height=12 > 結束時間</Th> <TD align=center><IMG height=1 src="pics/empty.gif" width=10><h:inputText id="DATE_END" value="#{queryBean.dateEnd}" onfocus="calendar()" /><IMG height=1 src="pics/empty.gif" width=10></TD> <th align=center> 得獎用戶<IMG height=1 src="pics/empty.gif" width=10> <h:selectBooleanCheckbox value="#{queryBean.onlyPrize}" readonly="true"/> <IMG height=1 src="pics/empty.gif" width=10></th> <th align=center> 辦事處 </th> <td align=center> <IMG height=1 src="pics/empty.gif" width=10> <h:selectOneMenu id="city" required="true" value="#{queryBean.org}" > <f:selectItems value="#{queryBean.items}"/> </h:selectOneMenu><IMG height=1 src="pics/empty.gif" width=10> </td> </TR> <tr> <th>PSID號碼</th> <td align=center><IMG height=1 src="pics/empty.gif" width=5><h:inputText id="PSID" value="#{queryBean.psid}" /> <IMG height=1 src="pics/empty.gif" width=10></td> <th>驗證碼</th> <td align=center><IMG height=1 src="pics/empty.gif" width=10><h:inputText id="PWD" value="#{queryBean.pwd}" /><IMG height=1 src="pics/empty.gif" width=10></td> <td></td><th>電話號碼</th> <td align=center><IMG height=1 src="pics/empty.gif" width=10><h:inputText id="TEL" value="#{queryBean.tel}" /><IMG height=1 src="pics/empty.gif" width=10></td> </tr> <TR > <TD align=middle height=35 colspan=7><h:commandButton type="submit" value="查詢" id="Submit" actionListener="#{queryBean.reset}" /> <h:commandButton type="submit" value="导出" actionListener="#{queryBean.export}" /> </TD></TR> </h:form> <tr bgcolor=#fffff> <td align=center colspan=7 bgcolor=#FFFFD1>**提示：如果需要查看2006-10-1號信息，開始時間輸入2006-10-1，結束時間輸入2006-10-2</td></tr></table><p><h:outputText /> <p> <h:form id="frmData"> <h:dataTable stylecellspacing="0" cellpadding="1" border="1" id="userList" value="#{queryBean.dataModel}" var="p" rows="50" width="100%" rowClasses="evenColumn,oddColumn"> <h:column> <f:facet name="header"> <h:outputText value="序號"/> </f:facet> <h:outputText value="#{p.id}" /> </h:column> <h:column> <f:facet name="header"> <h:outputText value="PSID"/> </f:facet> <h:outputText value="#{p.psid}" /> </h:column> <h:column> <f:facet name="header"> <h:outputText value="姓名"/> </f:facet> <h:outputText value="#{p.name}" /> </h:column> <h:column> <f:facet name="header"> <h:outputText value="獎項"/> </f:facet> <h:outputText value="#{p.prizeCode}" /> </h:column> <h:column> <f:facet name="header"> <h:outputText value="電話號碼"/> </f:facet> <h:outputText value="#{p.tel}" /> </h:column> <h:column> <f:facet name="header"> <h:outputText value="領獎號碼"/> </f:facet> <h:outputText value="#{p.telPrize}" /> </h:column> <h:column> <f:facet name="header"> <h:outputText value="驗證碼"/> </f:facet> <h:outputText value="#{p.pwd}" /> </h:column> <h:column> <f:facet name="header"> <h:outputText value="办事处"/> </f:facet> <h:outputText value="#{p.orgName}" /> </h:column> <h:column> <f:facet name="header"> <h:outputText value="參與時間"/> </f:facet> <h:outputText value="#{p.joinDate}" /> </h:column> </h:dataTable> <corejsf:pager dataTableId="userList" showpages="20" selectedStyleCMM_club_prize_joined_users "); } if (pagesize <= 0) pagesize = itemcount; int pages = itemcount / pagesize; if (itemcount % pagesize != 0) pages++; int currentPage = first / pagesize; if (first >= itemcount - pagesize) currentPage = pages - 1; int startPage = 0; int endPage = pages; if (showpages > 0) { startPage = (currentPage / showpages) * showpages; endPage = Math.min(startPage + showpages, pages); } writer.write("共计"+pages+"页"+itemcount+"条记录"); if (currentPage > 0) writeLink(writer, component, formId, id, "<", styleClass); if (startPage > 0) writeLink(writer, component, formId, id, "<<", styleClass); for (int i = startPage; i < endPage; i++) { writeLink(writer, component, formId, id, "" + (i + 1), i == currentPage ? selectedStyleClass : styleClass); } if (endPage < pages) writeLink(writer, component, formId, id, ">>", styleClass); if (first < itemcount - pagesize) writeLink(writer, component, formId, id, ">", styleClass); writeInput(writer,component,formId,id,styleClass); // FacesContext facesContext = FacesContext.getCurrentInstance(); // hidden field to hold result writeHiddenField(writer, component, id); } public void decode(FacesContext context, UIComponent component) { String id = component.getClientId(context); Map parameters = context.getExternalContext() .getRequestParameterMap(); String response = (String) parameters.get(id); String dataTableId = (String) get(context, component, "dataTableId"); Integer a = (Integer) get(context, component, "showpages"); int showpages = a == null ? 0 : a.intValue(); UIData data = (UIData) findComponent(context.getViewRoot(), getId(dataTableId, id), context); int first = data.getFirst(); int itemcount = data.getRowCount(); int pagesize = data.getRows(); if (pagesize <= 0) pagesize = itemcount; if (response.equals("<")) first -= pagesize; else if (response.equals(">")) first += pagesize; else if (response.equals("<<")) first -= pagesize * showpages; else if (response.equals(">>")) first += pagesize * showpages; else { int page=0; int num=convertNum(response); if ((num>0)&&(num<=itemcount/pagesize+1)){ page = Integer.parseInt(response); first = (page - 1) * pagesize; } } if (first < 0) first = 0; data.setFirst(first); }
贴张投入应用的图：
