看到論壇上有同學在問關於分頁的東西,我這裏把自己一些分頁的技巧整理下發上來...因爲這是在實際項目使用的,,,所以跟其他一些業務方法有關聯...還有就是使用了struts和JSTL(包括EL)標籤庫...
效果如下圖:
bean代碼:
* 創建日期 2006-1-26
* @author Woden Wang
* power by Heatpixel.com
*/
package org.woden.model;
import org.woden.facade.IPageCutter;
public class PageCutter implements IPageCutter{
private int pageLength=10; //每頁最大顯示記錄數
private int totalRecord; //總記錄數
private int currentPage=0; //當前頁
private static final int LENGTH = 5; //分頁間隔
/**
* 判斷當前頁是否末頁
* @return
*/
public boolean hasNextPage()
{
return currentPage<getTotalPage();
}
/**
* 判斷當前頁是否首頁
* @return
*/
public boolean hasPreviousPage()
{
return currentPage>1;
}
/**
* 判斷是否出現邏輯錯誤
* @return
*/
public boolean hasError()
{
return (getCurrentPage()>getTotalPage()||getCurrentPage()<1);
}
/**
* 獲取當前頁
* @return
*/
public int getCurrentPage() {
return currentPage;
}
/**
* 設置當前頁
* @param currentPage
*/
public void setCurrentPage(int currentPage) {
this.currentPage = currentPage;
}
/**
* 獲取當前記錄數
* @return
*/
public int getCurrentRecord() {
if(currentPage==0)
return 0;
return pageLength*(currentPage-1);
}
/**
* 獲取頁面長度
* @return
*/
public int getPageLength() {
return pageLength;
}
/**
* 設置頁面長度
* @param pageLength
*/
public void setPageLength(int pageLength) {
this.pageLength = pageLength;
}
/**
* 獲取頁面總數
* @return
*/
public int getTotalPage() {
return (totalRecord%pageLength==0)?totalRecord/pageLength:totalRecord/pageLength+1;
}
/**
* 獲取記錄總數
* @return
*/
public int getTotalRecord() {
return totalRecord;
}
/**
* 設置記錄總數
* @param totalRecord
*/
public void setTotalRecord(int totalRecord) {
this.totalRecord = totalRecord;
}
/**
* 頁面循環開始
* @return
*/
public int getBeginPage()
{
int begin = this.currentPage - LENGTH;
if(begin<=1)
return 1;
else
return begin;
}
/**
* 頁面循環結束
* @return
*/
public int getEndPage()
{
int end = this.currentPage + LENGTH;
if(end>=getTotalPage())
return getTotalPage();
else
return end;
}
/**
* 第一頁
* @return
*/
public int getFirstPage()
{
return 1;
}
/**
* 末頁
* @return
*/
public int getLastPage()
{
return getTotalPage();
}
}
說明下,這個bean實現的接口是我自己定義的,如果不是太複雜的java應用的話其實不需要用接口.(有興趣瞭解接口的優勢的朋友建議閱讀"門面模式"的相關文章)
標籤處理器類:
* 創建日期 2006-2-7
* @author Woden Wang
* power by Heatpixel.com
*/
package org.woden.controller.tag;
import org.apache.log4j.Logger;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.jsp.tagext.TagSupport;
import org.woden.facade.IPageCutter;
public class PageCut extends TagSupport{
/**
* Logger for this class
*/
private static final Logger logger = Logger.getLogger(PageCut.class);
private IPageCutter pageBean;
private String file;
public void setFile(String file)
{
this.file = filtePage(file);
}
public void setPageBean(IPageCutter pageBean)
{
this.pageBean = pageBean;
}
/**
* 對路徑進行特殊處理
* @param file
* @return
*/
private static String filtePage(String file)
{
String querys = file.substring(file.indexOf("?")+1);
String path = file.substring(0,file.indexOf("?")+1);
String query[] = querys.split("&");
for(int i=0;i<query.length;i++)
{
if(query[i].startsWith("page=")||query[i].equals(""))
continue;
path+=query[i]+"&";
}
return path.substring(0,path.length()-1);
}
public int doStartTag()
{
HttpServletRequest request = (HttpServletRequest)pageContext.getRequest();
if(file.equals("")||pageBean==null)
return SKIP_BODY;
try
{
request.setAttribute("path",this.file);
request.setAttribute("pageBean",pageBean);
pageContext.include("/templet/page_cutter.jsp");
}
catch (Exception e)
{
logger.warn("獲取頁面文件失敗.");
}
return SKIP_BODY;
}
}
以下是/templet/page_cutter.jsp的代碼:
<%@ taglib uri="http://struts.apache.org/tags-bean" prefix="bean"%>
<%@ taglib uri="http://struts.apache.org/tags-html" prefix="html"%>
<%@ taglib uri="http://struts.apache.org/tags-logic" prefix="logic"%>
<%@ taglib uri="http://java.sun.com/jstl/core" prefix="c"%>
<!--分頁-->
<p>
<table width="100%" border="0" cellspacing="0" cellpadding="0">
<tr>
<td bgcolor="#f5f5f5" height="30">
<img src="images/spacer.gif" width="10" height="8">
<bean:message key="jsp.global.cutPage.current" /><%--顯示"Current Page"--%>
<span class="title">${pageBean.currentPage}</span> of ${pageBean.totalPage}
</td>
<td align="right" bgcolor="#f5f5f5">
<bean:message key="jsp.global.cutPage.click" /><%--顯示"Click to View Page"--%>
<c:if test="${pageBean.beginPage>1}">
<html:link page="${path}" paramId="page" paramName="pageBean" paramProperty="firstPage">${pageBean.firstPage}</html:link>...</c:if>
<c:forEach begin="${pageBean.beginPage}" end="${pageBean.endPage}" step="1" var="i">
<c:if test="${i==pageBean.currentPage}">
<span class="title">${i}</span>
</c:if>
<c:if test="${i!=pageBean.currentPage}">
<html:link page="${path}" paramId="page" paramName="i">${i}</html:link>
</c:if>
</c:forEach>
<c:if test="${pageBean.endPage<pageBean.totalPage}">...<html:link page="${path}" paramId="page" paramName="pageBean" paramProperty="lastPage">${pageBean.lastPage}</html:link>
</c:if>
<img src="images/spacer.gif" width="10" height="8" border="0" />
</td>
</tr>
</table>
</p>
由 於我用來struts框架,,,所以這裏用到了struts的標籤...其實如果沒用struts的話也可以去處那些標籤,也就是把<html: link>改成<a href=...>,,,把<bean:message>直接改成要顯示的文字就可以了...
標籤定義(tld):
<tag>
<name>cutPage</name>
<tag-class>org.woden.controller.tag.PageCut</tag-class>
<body-content>jsp</body-content>
<attribute>
<name>file</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>pageBean</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
</tag>
標籤調用文件(list.jsp),爲了不影響大家閱讀,,,這裏省去了部分代碼...
<%@ taglib uri="http://struts.apache.org/tags-bean" prefix="bean"%>
<%@ taglib uri="http://struts.apache.org/tags-html" prefix="html"%>
<%@ taglib uri="http://struts.apache.org/tags-logic" prefix="logic"%>
<%@ taglib uri="http://struts.apache.org/tags-tiles" prefix="tiles"%>
<%@ taglib uri="business" prefix="business"%><%--用戶業務標籤庫,包括分頁標籤就在這裏定義--%>
<bean:parameter name="page" id="currentPage" value="1" />
<%--
這裏省去了部分代碼,代碼實例會在後面講解.
--%>
<table width="100%" border="0" cellpadding="3" cellspacing="1" bgcolor="#aaaaaa">
<tr style=" background-color:#eeeeee;text-align:center" class="titles">
<td height="28">
測試的循環
</td>
</tr>
<logic:iterate id="news" name="list" type="org.woden.facade.news.INews">
<%--
這裏是業務循環標籤,相當於把保存在list裏面的每個news對象遍歷出來,
大概可以理解成:從數據庫讀出的列表數據(可能總數100條,這裏讀出10條,分頁嘛)放到list裏面,
並返回一個pageCutter對象,大概的demo操作我下面會給出.
--%>
<!--循環開始-->
<tr style=" background-color:#ffffff;text-align:center">
<td>
<%--顯示業務邏輯,,,已刪除--%>
</td>
</tr>
<!--循環結束-->
</logic:iterate>
</table>
<%--pageCutter是分頁對象名,這裏調用標籤將分頁對象裏面的內容顯示出來--%>
<business:cutPage file="${pageContext.request.servletPath}?${pageContext.request.queryString}"
pageBean="${pageCutter}" />
最後這裏說說大概的數據庫操作:
//currentPage是外部傳進來頁數
IPageCutter page = new PageCutter();
page.setCurrentPage(currentPage);
page.setTotalRecord(getAllNewsCount());
List list = listAllNews(page.getPageLength(),page.getCurrentRecord());
//假如page.getPageLength()等於10,page.getCurrentRecord()等於13
//listAllNews方法返回從數據庫第13條記錄開始,到第23條記錄結束的10條記錄
最後說明下,我是個追求良好設計模式很刻骨的人,,,所以可能會出現一些接口啊,,,門面層這類的,,,還有爲了追求所謂的MVC,,,我在JSP頁面也沒寫任何的java語句/表達式,,,取而代之的是EL和JSTL...
還有,因爲這個是在某實際項目中摘錄下來的,所以頁面內容都是資源文件中的,,,大家湊合着看...
-------------------------------------------------------------------------------------下面是非MVC的分頁---------------------------------
這個是asp式的分頁...我從以前asp裏面翻譯過來的...
list.jsp:
<%@ page import="java.sql.*"%>
<%Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver")
.newInstance();
String url = "jdbc:microsoft:sqlserver://localhost;DatabaseName=pagetest";
String user = "sa";
String password = "";
Connection conn = DriverManager.getConnection(url, user, password);
Statement stmt = conn
.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,
ResultSet.CONCUR_UPDATABLE);
String sql = "select * from test order by id";//這裏的test裏面只有兩個字段,一個id(主鍵,自動增1),一個是test(vachar)
ResultSet rs = stmt.executeQuery(sql);
rs.last();//將記錄遊標移動到最末,從而計算出共有多少條記錄,方便分頁統計
if (rs.getRow() == 0) {//如果記錄數爲0就顯示"沒有內容"
%>
沒有內容
<%
} else {
//page module
int count_per_page = 5; //每頁5個記錄
int page_on = 1; //當前頁
int total_record = 0; //記錄總數
int total_page = 0; //總頁數
total_record = rs.getRow();
if (total_record % count_per_page == 0)
total_page = total_record / count_per_page;
else
total_page = total_record / count_per_page + 1;
if ("".equals(request.getParameter("page"))
|| request.getParameter("page") == null)
page_on = 1;
else
page_on = Integer.parseInt(request.getParameter("page"));
if (page_on > total_page)
page_on = total_page;
if (page_on <= 0)
page_on = 1;
rs.absolute((page_on - 1) * count_per_page + 1); //put index
%>
<%
for (int i = 1; i <= count_per_page; i++) {
%>
<p>
<%=rs.getString("test")%><%--這裏循環顯示數據--%>
</p>
<%if (!rs.next())
break;
}//end for
%>
<%--show count--%>
<%
String filename = "list.jsp?";
int page_show_begin = 0; //began showed page
int page_show_end = 0; //ended showed page
int page_show_max = 6; //max showed page
if ((page_on - 1) > page_show_max)
page_show_begin = page_on - page_show_max + 1;
else
page_show_begin = 1;
if (total_page - page_on > page_show_max)
page_show_end = page_on + page_show_max - 1;
else
page_show_end = total_page;
%>
<table width="100%" border="0" cellspacing="0" cellpadding="0">
<tr>
<td height="30"></td>
<td bgcolor="#f5f5f5">
<img src="images/spacer.gif" width="10" height="8">
Currently Viewing Page <span class="title"><%=page_on%></span> of
<%=total_page%>
</td>
<td align="right" bgcolor="#f5f5f5">
Click to View Page:
<%if (page_show_begin != 1) {%>
<%if (page_on == 1) {%>
<span class="title"><%=page_on%></span>
<%} else {
%>
<a href="<%=filename%>page=1">1</a>
<%}%>
...
<%}%>
<%for (int a = page_show_begin; a <= page_show_end; a++) {%>
<%if (a == page_on) {%>
<span class="title"><%=a%></span>
<%} else {%>
<a href="<%=filename%>page=<%=a%>"><%=a%></a>
<%}%>
<%}%>
<%if (page_show_end != total_page) {%>
...
<%if (total_page == page_on) {%>
<span class="title"><%=page_on%></span>
<%} else {
%>
<a href="<%=filename%>page=<%=total_page%>"><%=total_page%></a>
<%}
}
%>
<img src="images/spacer.gif" width="10" height="8" border="0">
</td>
</tr>
</table>
<%--View--%>
<%}
rs.close();
stmt.close();
conn.close();
%>
建表的ddl:
CREATE TABLE [dbo].[test] (
[id] [int] IDENTITY (1, 1) NOT NULL ,
[test] [varchar] (255) COLLATE Chinese_PRC_CI_AS NULL
) ON [PRIMARY]
GO
我這裏主要想介紹分頁,所以爲了簡單起見,直接在頁面上連接數據庫...
具體要執行本例子的方法:隨便建個tomcat項目,,,記住要導入mssqlserver那三個JDBC驅動就可以了...只要保證數據庫連接就可以執行了...
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