这里把自己一些分页的技巧整理下发上来...因为这是在实际项目使用的,,,所以跟其他一些业务方法有关联...还有就是使用了struts和JSTL(包括EL)标签库...
效果如下图:
bean代码:
CODE:/*
* 创建日期 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; //每页最大显示记录数
private int totalRecord; //总记录数
private int currentPage=0; //当前页
private static final int LENGTH = 5; //分页间隔
/**
* 判断当前页是否末页
* @return
*/
public boolean hasNextPage()
{
return currentPage<getTotalPage();
}
/**
* 判断当前页是否首页
* @return
*/
public boolean hasPreviousPage()
{
return currentPage>1;
}
/**
* 判断是否出现逻辑错误
* @return
*/
public boolean hasError()
{
return (getCurrentPage()>getTotalPage()||getCurrentPage()<1);
}
/**
* 获取当前页
* @return
*/
public int getCurrentPage() {
return currentPage;
}
/**
* 设置当前页
* @param currentPage
*/
public void setCurrentPage(int currentPage) {
this.currentPage = currentPage;
}
/**
* 获取当前记录数
* @return
*/
public int getCurrentRecord() {
if(currentPage==0)
return 0;
return pageLength*(currentPage-1);
}
/**
* 获取页面长度
* @return
*/
public int getPageLength() {
return pageLength;
}
/**
* 设置页面长度
* @param pageLength
*/
public void setPageLength(int pageLength) {
this.pageLength = pageLength;
}
/**
* 获取页面总数
* @return
*/
public int getTotalPage() {
return (totalRecord%pageLength==0)?totalRecord/pageLength:totalRecord/pageLength+1;
}
/**
* 获取记录总数
* @return
*/
public int getTotalRecord() {
return totalRecord;
}
/**
* 设置记录总数
* @param totalRecord
*/
public void setTotalRecord(int totalRecord) {
this.totalRecord = totalRecord;
}
/**
* 页面循环开始
* @return
*/
public int getBeginPage()
{
int begin = this.currentPage - LENGTH;
if(begin<=1)
return 1;
else
return begin;
}
/**
* 页面循环结束
* @return
*/
public int getEndPage()
{
int end = this.currentPage + LENGTH;
if(end>=getTotalPage())
return getTotalPage();
else
return end;
}
/**
* 第一页
* @return
*/
public int getFirstPage()
{
return 1;
}
/**
* 末页
* @return
*/
public int getLastPage()
{
return getTotalPage();
}
}
说明下,这个bean实现的接口是我自己定义的,如果不是太复杂的java应用的话其实不需要用接口.(有兴趣了解接口的优势的朋友建议阅读"门面模式"的相关文章)
标签处理器类:
CODE:/*
* 创建日期 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;
}
/**
* 对路径进行特殊处理
* @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("获取页面文件失败.");
}
return SKIP_BODY;
}
}
以下是/templet/page_cutter.jsp的代码:
CODE:<%@ page contentType="text/html;charset=UTF-8"%>
<%@ 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"%>
<!--分页-->
<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" /><%--显示"Current Page"--%>
<span class="title">${pageBean.currentPage}</span> of ${pageBean.totalPage}
</td>
<td align="right" bgcolor="#f5f5f5">
<bean:message key="jsp.global.cutPage.click" /><%--显示"Click to View Page"--%>
<c:if test="${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 于我用来struts框架,,,所以这里用到了struts的标签...其实如果没用struts的话也可以去处那些标签,也就是把<html: link>改成<a href=...>,,,把<bean:message>直接改成要显示的文字就可以了...
标签定义(tld):
CODE: <!--分页显示标签-->
<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>
标签调用文件(list.jsp),为了不影响大家阅读,,,这里省去了部分代码...
CODE:<%@ page contentType="text/html;charset=UTF-8"%>
<%@ 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"%><%--用户业务标签库,包括分页标签就在这里定义--%>
<bean:parameter name="page" id="currentPage" value="1" />
<%--
这里省去了部分代码,代码实例会在后面讲解.
--%>
<table width="100%" border="0" cellpadding="3" cellspacing="1" bgcolor="#aaaaaa">
<tr style=" background-color:#eeeeee;text-align:center" class="titles">
<td height="28">
测试的循环
</td>
</tr>
<logic:iterate id="news" name="list" type="org.woden.facade.news.INews">
<%--
这里是业务循环标签,相当于把保存在list里面的每个news对象遍历出来,
大概可以理解成:从数据库读出的列表数据(可能总数100条,这里读出10条,分页嘛)放到list里面,
并返回一个pageCutter对象,大概的demo操作我下面会给出.
--%>
<!--循环开始-->
<tr style=" background-color:#ffffff;text-align:center">
<td>
<%--显示业务逻辑,,,已删除--%>
</td>
</tr>
<!--循环结束-->
</logic:iterate>
</table>
<%--pageCutter是分页对象名,这里调用标签将分页对象里面的内容显示出来--%>
<business:cutPage file="${pageContext.request.servletPath}?${pageContext.request.queryString}"
pageBean="${pageCutter}" />
最后这里说说大概的数据库操作:
//currentPage是外部传进来页数
IPageCutter page = new PageCutter();
page.setCurrentPage(currentPage);
page.setTotalRecord(getAllNewsCount());
List list = listAllNews(page.getPageLength(),page.getCurrentRecord());
//假如page.getPageLength()等于10,page.getCurrentRecord()等于13
//listAllNews方法返回从数据库第13条记录开始,到第23条记录结束的10条记录
最后说明下,我是个追求良好设计模式很刻骨的人,,,所以可能会出现一些接口啊,,,门面层这类的,,,还有为了追求所谓的MVC,,,我在JSP页面也没写任何的java语句/表达式,,,取而代之的是EL和JSTL...
还有,因为这个是在某实际项目中摘录下来的,所以页面内容都是资源文件中的,,,大家凑合着看...
-------------------------------------------------------------------------------------下面是非MVC的分页---------------------------------
这个是asp式的分页...我从以前asp里面翻译过来的...
list.jsp:
CODE:<%@ page contentType="text/html;charset=gbk"%>
<%@ 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";//这里的test里面只有两个字段,一个id(主键,自动增1),一个是test(vachar)
ResultSet rs = stmt.executeQuery(sql);
rs.last();//将记录游标移动到最末,从而计算出共有多少条记录,方便分页统计
if (rs.getRow() == 0) {//如果记录数为0就显示"没有内容"
%>
没有内容
<%
} else {
//page module
int count_per_page = 5; //每页5个记录
int page_on = 1; //当前页
int total_record = 0; //记录总数
int total_page = 0; //总页数
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")%><%--这里循环显示数据--%>
</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
我这里主要想介绍分页,所以为了简单起见,直接在页面上连接数据库...
具体要执行本例子的方法:随便建个tomcat项目,,,记住要导入mssqlserver那三个JDBC驱动就可以了...只要保证数据库连接就可以执行了...
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