The whole process of JSP custom paging tag TAG

首先我们需要在WEB-INF/tld/目录下创建page.tld文件

<?xml version="1.0" encoding="ISO-8859-1"?> 
<taglib> 
<tlib-version>1.0</tlib-version> 
<jsp-version>1.2</jsp-version> 
<short-name>page</short-name> 
<uri>http://www.kevin.com/taglibs/page</uri> 
<tag> 
<name>htmlPage</name> 
<tag-class>com.lss.common.tag.PageTag</tag-class> 
<body-content>JSP</body-content> 
<description>htmlPage Tag</description> 
<attribute> 
<name>pageNo</name> 
<required>false</required> 
<rtexprvalue>true</rtexprvalue> 
</attribute> 
<attribute> 
<name>pageSize</name> 
<required>false</required> 
<rtexprvalue>true</rtexprvalue> 
</attribute> 
<attribute> 
<name>totalSum</name> 
<required>true</required> 
<rtexprvalue>true</rtexprvalue> 
</attribute> 
<attribute> 
<name>url</name> 
<required>true</required> 
<rtexprvalue>true</rtexprvalue> 
</attribute> 
<attribute> 
<name>showPage</name> 
<required>false</required> 
<rtexprvalue>true</rtexprvalue> 
</attribute> 
</tag> 
</taglib>

package com.lss.common.tag; 
 
import java.io.IOException; 
 
import javax.servlet.jsp.JspException; 
import javax.servlet.jsp.JspWriter; 
import javax.servlet.jsp.tagext.TagSupport; 
 
import com.lss.common.page.HtmlPage; 
import com.lss.common.page.Page; 
import com.lss.common.page.VariablePage; 
 
/** 
* 分页处理标签 
* 
* @description 
* @DATE 2012-3-11下午09:08:46 
*/
public class PageTag extends TagSupport { 
private int pageNo; 
private int pageSize = 10; 
private int totalSum; 
private int showPage = 10; 
private String url; 
 
public int getPageNo() { 
return pageNo; 
} 
 
public void setPageNo(int pageNo) { 
this.pageNo = pageNo; 
} 
 
public int getPageSize() { 
return pageSize; 
} 
 
public void setPageSize(int pageSize) { 
this.pageSize = pageSize; 
} 
 
public int getTotalSum() { 
return totalSum; 
} 
 
public void setTotalSum(int totalSum) { 
this.totalSum = totalSum; 
} 
 
public int getShowPage() { 
return showPage; 
} 
 
public void setShowPage(int showPage) { 
this.showPage = showPage; 
} 
 
public String getUrl() { 
return url; 
} 
 
public void setUrl(String url) { 
this.url = url; 
} 
 
@Override
public int doEndTag() throws JspException { 
if (pageSize == 0) { 
return TagSupport.SKIP_PAGE;// 不显示分页 
} else if (pageSize > totalSum) { 
return TagSupport.SKIP_BODY;// 不显示分页 
} 
JspWriter out = pageContext.getOut(); 
try { 
if (url.indexOf(";jsessionid=") == -1) { 
if (url.indexOf("?") == -1) { 
url += ";jsessionid=" + pageContext.getSession().getId() + "?pageNo="; 
} else { 
url = url.replaceFirst("\\?", ";jsessionid=" + pageContext.getSession().getId() + "?"); 
if (url.indexOf("pageNo=") == -1) { 
url += "&pageNo="; 
} 
} 
} 
url = pageContext.getServletContext().getContextPath() + url; 
VariablePage variablePage = new VariablePage(pageNo, totalSum, pageSize, url); 
variablePage.setShowPageNum(showPage); 
Page page = new HtmlPage(variablePage); 
out.print(page.getFirstNo() + " " + page.getBackpageNum() + " " + page.pagination() + " " + page.getNextpageNum() + " " + page.getLastNo()); 
} catch (IOException ex) { 
ex.printStackTrace(); 
} 
return super.doEndTag(); 
} 
 
@Override
public void release() { 
url = null; 
pageNo = 0; 
totalSum = 0; 
pageSize = 10; 
super.release(); 
} 
 
private static final long serialVersionUID = -2642907859641024483L; 
}

/** 
* HTML 分页类 
* 
* @description 
* @DATE 2012-3-11下午10:33:14 
*/
public class HtmlPage extends Page { 
public HtmlPage(VariablePage variablePage) { 
super(variablePage); 
} 
 
public String pagination() { 
String printNo = ""; 
// 如果已分页；并且页数小于等于要显示的页数 
if (variablePage.totalPage > 1 && variablePage.totalPage <= variablePage.showPageNum) { 
return displayAll(); 
// 如果分页数：大于显示的页码数 
} else if (variablePage.totalPage > 1 && variablePage.totalPage > variablePage.showPageNum) { 
if (variablePage.pageNo == 1) {// 当前页等于第一页 
return fromFirstPagePrint(); 
} else if (variablePage.pageNo == variablePage.totalPage) {// 当前页等于最后一页 
return fromLastPagePrint(); 
} else {// 如果当前页：即不是首页也不是尾页 
if (variablePage.showPageNum % 2 == 0) {// 可以平分页码 
int print$No = variablePage.showPageNum / 2; 
if (variablePage.pageNo >= print$No) { 
int index$No = variablePage.pageNo - print$No; 
if (variablePage.pageNo + print$No >= variablePage.totalPage) { 
return fromLastPagePrint(); 
} else { 
if (index$No == 0) 
index$No = 1; 
for (int i = index$No; i < (variablePage.showPageNum + index$No); i++) { 
if (i == variablePage.pageNo) {// 如果是当前页:不添加连接URL 
printNo += (i + variablePage.split); 
} else { 
printNo += (buildA(variablePage, i) + variablePage.split); 
} 
} 
} 
} else { 
return fromFirstPagePrint(); 
} 
} else {// 打印页数不是偶数时： 
int print$No = variablePage.showPageNum / 2 + 1; 
if (variablePage.pageNo >= print$No && variablePage.pageNo + print$No < variablePage.totalPage) { 
int index$No = variablePage.pageNo - print$No + 1; 
for (int i = index$No; i < variablePage.showPageNum + index$No; i++) { 
if (i == variablePage.pageNo) {// 如果是当前页:不添加连接URL 
printNo += (i + variablePage.split); 
} else { 
printNo += (buildA(variablePage, i) + variablePage.split); 
} 
} 
} else if (variablePage.pageNo <= print$No) {// 从第一页开始 
return fromFirstPagePrint(); 
} else { 
return fromLastPagePrint(); 
} 
} 
} 
return (printNo); 
} else { 
return "1"; 
} 
} 
 
public String getBackpageNum() { 
if (variablePage.pageNo <= 1) { 
return buildSpan("上一页", variablePage); 
} else { 
return buildA("上一页", (variablePage.url + (variablePage.pageNo - 1))); 
} 
} 
 
public String getNextpageNum() { 
if (variablePage.pageNo >= variablePage.totalPage) { 
return buildSpan("下一页", variablePage); 
} else { 
return buildA("下一页", variablePage.url + (variablePage.pageNo + 1)); 
} 
} 
 
public String buildSpan(String text, VariablePage variablePage) { 
return "<span style=\"color:gray;\">" + text + "</span>"; 
} 
 
public String buildA(String text, String url) { 
return "<a href=\"" + url + "\">" + text + "</a>"; 
} 
 
public String buildA(VariablePage variablePage, int num) { 
return ("<a href=\"" + variablePage.url + num + "\">" + num + "</a>"); 
} 
}

public abstract class Page { 
protected VariablePage variablePage; 
 
public Page(VariablePage variablePage) { 
this.variablePage = variablePage; 
calculateTotalPage(); 
} 
 
public int getStartIndex() { 
return (getValidpageNum() - 1) * variablePage.pageSize; 
} 
 
public String getBackpageNum() { 
if (variablePage.pageNo <= 1) { 
return buildSpan("上一页", variablePage); 
} else { 
return buildA("上一页", variablePage.getUrl() + (variablePage.pageNo - 1)); 
} 
} 
 
public String getNextpageNum() { 
if (variablePage.pageNo >= variablePage.totalPage) { 
return buildSpan("下一页", variablePage); 
} else { 
return buildA("下一页", variablePage.getUrl() + (variablePage.pageNo + 1)); 
} 
} 
 
/** 
* 计算总页数 
*/
private void calculateTotalPage() { 
if (variablePage.totalSum % variablePage.pageSize == 0) { 
variablePage.totalPage = variablePage.totalSum / variablePage.pageSize; 
} else { 
variablePage.totalPage = variablePage.totalSum / variablePage.pageSize + 1; 
} 
if (variablePage.totalPage < variablePage.pageNo) { 
variablePage.pageNo = variablePage.totalPage; 
} else if (variablePage.pageNo < 1) { 
variablePage.pageNo = 1; 
} 
} 
 
protected String displayAll() { 
StringBuilder sBuilder = new StringBuilder(10); 
sBuilder.append(variablePage.split); 
for (int i = 1; i <= variablePage.totalPage; i++) { 
if (i == variablePage.pageNo) { 
sBuilder.append(i + variablePage.split); 
} else { 
sBuilder.append(buildA(variablePage, i) + variablePage.split); 
} 
} 
return sBuilder.toString(); 
} 
 
/** 
* 抽象出分页方法 
* 
* @return 
*/
public abstract String pagination(); 
 
/** 
* 实现从第一页开始打印 
* 
* @return 
*/
protected final String fromFirstPagePrint() { 
StringBuffer buffer = new StringBuffer(100); 
for (int i = 1; i <= variablePage.showPageNum; i++) { 
if (i == variablePage.pageNo) {// 如果是当前页:不添加连接URL 
buffer.append(i + variablePage.split); 
} else { 
buffer.append(buildA(variablePage, i) + variablePage.split); 
} 
} 
return buffer.toString(); 
} 
 
/** 
* 实现从最后一页开始打印 
* 
* @return 
*/
protected final String fromLastPagePrint() { 
StringBuffer buffer = new StringBuffer(100); 
int startPage = variablePage.totalPage - (variablePage.showPageNum - 1); 
for (int i = startPage; i <= variablePage.totalPage; i++) { 
if (i == variablePage.pageNo) {// 如果是当前页:不添加连接URL 
buffer.append(i + variablePage.split); 
} else { 
buffer.append(buildA(variablePage, i) + variablePage.split); 
} 
} 
return buffer.toString(); 
} 
 
public String getFirstNo() { 
if (isExistsPagination()) { 
return buildA("首页", variablePage.url + 1); 
} else { 
return buildSpan("首页", variablePage); 
} 
} 
 
/** 
* 判断是否存在分页 
* 
* @return 
*/
private boolean isExistsPagination() { 
if (variablePage.totalSum > 1 && variablePage.totalPage > 1) { 
return true; 
} 
return false; 
} 
 
public String getLastNo() { 
if (isExistsPagination()) { 
return buildA("尾页", variablePage.url + variablePage.totalPage); 
} else { 
return buildSpan("尾页", variablePage); 
} 
} 
 
protected int getValidpageNum() { 
if (variablePage.totalPage < variablePage.pageNo) { 
return variablePage.pageNo = variablePage.totalPage; 
} else if (variablePage.pageNo < 1) { 
return variablePage.pageNo = 1; 
} else { 
return variablePage.pageNo; 
} 
} 
 
public VariablePage getPageContant() { 
return this.variablePage; 
} 
 
public abstract String buildSpan(String text, VariablePage variablePage); 
 
public abstract String buildA(String text, String url); 
 
public abstract String buildA(VariablePage variablePage, int num); 
 
public String printModifyPageSize(int pageSize){ 
StringBuilder builder=new StringBuilder(100); 
builder.append("每页<input type=&#39;text&#39; id=&#39;pageSize&#39; style=&#39;width:20px&#39; maxlength=&#39;2&#39; name=&#39;pageSize&#39;"); 
if(pageSize>0){ 
builder.append(" value=&#39;"+pageSize+"&#39; "); 
} 
builder.append("/>条"); 
return builder.toString(); 
} 
}

/** 
* 分页基础变量 
* 
* @description 
* @DATE 2012-3-11下午10:34:00 
*/
public class SimpleVariable { 
/** 
* 显示页码 
*/
protected int showPageNum = 10; 
/** 
* 连接URL 
*/
protected String url = null; 
/** 
* 当前页码 
*/
protected int pageNo = 1; 
/** 
* 总页码 
*/
protected int totalPage = 1; 
/** 
* 总条数 
*/
protected int totalSum = 0; 
/** 
* 每页显示条数 
*/
protected int pageSize = 10; 
 
public String getUrl() { 
return url; 
} 
 
public void setUrl(String url) { 
this.url = url; 
} 
 
public int getTotalPage() { 
return totalPage; 
} 
 
public void setTotalPage(int totalPage) { 
this.totalPage = totalPage; 
} 
 
public int getTotalSum() { 
return totalSum; 
} 
 
public void setTotalSum(int totalSum) { 
this.totalSum = totalSum; 
} 
 
public int getPageSize() { 
return pageSize; 
} 
 
public void setPageSize(int pageSize) { 
this.pageSize = pageSize; 
} 
 
public int getShowPageNum() { 
return showPageNum; 
} 
 
public void setShowPageNum(int showPageNum) { 
this.showPageNum = showPageNum; 
} 
 
public int getPageNo() { 
return pageNo; 
} 
 
public void setPageNo(int pageNo) { 
this.pageNo = pageNo; 
} 
}

/** 
* 分页变量 
* 
* @description 
* @DATE 2012-3-11下午10:34:08 
*/
public class VariablePage extends SimpleVariable { 
protected String split = " "; 
protected String style = "class='page'"; 
 
public VariablePage(int pageNo, int totalSum, int pageSize, String url) { 
pageNo = pageNo < 1 ? 1 : pageNo; 
super.pageNo = pageNo; 
this.totalSum = totalSum; 
this.url = url; 
this.pageSize = pageSize; 
} 
 
public VariablePage(int pageNum, int totalSum, String url) { 
pageNum = pageNum < 1 ? 1 : pageNum; 
super.pageNo = pageNum; 
this.totalSum = totalSum; 
this.url = url; 
} 
 
public String getSplit() { 
return split; 
} 
 
public void setSplit(String split) { 
this.split = split; 
} 
 
}

#需要使用该分页标签的JSP 使用方法如下：

JSP 头部引入

<%@taglib uri="http://www.kevin.com/taglibs/page" prefix="page" %>

使用以下标签生成分页HTML代码

<page:htmlPage pageNo="${pageNo}" url="your_url" totalSum="${totalSum}" showPage="10" pageSize="12"/>

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