Mysql问题？？？ - 黑马程序员技术交流社区

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import javax.el.ELContext;
import javax.servlet.jsp.JspContext;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.SimpleTagSupport;
import com.sun.faces.spi.ManagedBeanFactory.Scope;
public class PartPageTag extends SimpleTagSupport {
private List source;// 被分页的集合接口
private String result;// 分页后的子集合
private String size;// 每页显示的数据数量
private String currentPage;// 当前页码
private int pageQuantity; // 总的分页数
public PartPageTag(){
System.out.println("实例化标签实现类对象");
}
@Override
public void doTag() throws JspException, IOException {
// TODO Auto-generated method stub
super.doTag();
JspContext jspContext=this.getJspContext();// 获得JspContext对象
int sum=source.size();// 获得集合大小
System.out.println("一共有数据:"+sum);
/*
* 判断每页显示的数据数量是否大于源集合中的数据数量
* */
List list=new ArrayList();//封装最后分页数据的集合
if(size==null || size.equals("")){// 如果此属性缺省或者是空值则不对集合进行分割
System.out.println("缺省数量");
list=source;
}else{// 如果size属性填入值，则进行比较
//判断每页显示的数量是否大于等于源集合大小
int num=Integer.parseInt(size);
if(num>=source.size()){// 如果大于或等于原集合大小则不分页
list=source;
}else{
pageQuantity=evalPagination(num);// 调用计算总页码数的方法
validatePage();// 调用验证页码是否在合法的范围方法
list=partitionSourceList(num);//调用分割集合的方法
}
}
jspContext.setAttribute("currentPage",currentPage, 2);// 把当前页码放入result作用域中
jspContext.setAttribute("pageQuantity",pageQuantity, 2);// 把当前页码总数放入result作用域中
jspContext.setAttribute(result, list, 2);// 把分页后数据封装到list中并以result标签属性作为引用存放在请求域中
}
/*计算总页码数的方法*/
private int evalPagination(int num){
System.out.println("计算总的页码数");
int sum;
sum=source.size()/num;// 总页数变量(集合大小除以每页显示的数据数)
//判断是否能够整除
if(source.size()%num !=0){// 如果不能够除尽则在总页数上加1，多显示一页
sum=sum+1;
}
return sum;
}
/*验证页码是否在合法的范围方法*/
private void validatePage(){
System.out.println("检验页码是否正确");
// 如果页码属性currentPage 为null，为空字符串，为字符串 0
if(currentPage==null||currentPage.equals("")||currentPage.equals("0"))
currentPage="1";// 设为第一页
//如果页码属性currentPage大于等于总的页码数
else if(Integer.parseInt(currentPage)>=pageQuantity){
currentPage=String.valueOf(pageQuantity);// 设为最后一页
}
}
/*分割集合的方法
* */
private List partitionSourceList(int num){
System.out.println("分割集合");
List res=new ArrayList();
if(Integer.parseInt(currentPage)>=pageQuantity){
if(source.size()%num ==0){
res=source.subList(Integer.parseInt(currentPage)
*Integer.parseInt(size)-Integer.parseInt(size),
Integer.parseInt(currentPage)
*Integer.parseInt(size)-Integer.parseInt(size)+Integer.parseInt(size));
}else{
res=source.subList(Integer.parseInt(currentPage)
*Integer.parseInt(size)-Integer.parseInt(size),
pageQuantity
*Integer.parseInt(size)-Integer.parseInt(size)+source.size()%num);
}
}
else{
res=source.subList(Integer.parseInt(currentPage)
*Integer.parseInt(size)-Integer.parseInt(size),
Integer.parseInt(currentPage)
*Integer.parseInt(size)-Integer.parseInt(size)+Integer.parseInt(size));
}
return res;
}
/*
* getter and setter methods ...
* */
public List getSource() {
return source;
}
public void setSource(List source) {
this.source = source;
}
public String getResult() {
return result;
}
public void setResult(String result) {
this.result = result;
}
public String getSize() {
return size;
}
public void setSize(String size) {
this.size = size;
}
public String getCurrentPage() {
return currentPage;
}
public void setCurrentPage(String currentPage) {
this.currentPage = currentPage;
}
}

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import java.io.IOException;
import javax.servlet.jsp.JspContext;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.SimpleTagSupport;
public class PagingLink extends SimpleTagSupport {
@Override
public void doTag() throws JspException, IOException {
// TODO Auto-generated method stub
super.doTag();
JspContext context=this.getJspContext();// 获得JspContext对象
JspWriter out=context.getOut();// 获得JspWriter对象
int current=Integer.parseInt(String.valueOf(context.getAttribute("currentPage", 2)));
int pagesum=Integer.parseInt(String.valueOf(context.getAttribute("pageQuantity", 2)));
out.print("<a href='?page=1'>首页</a> ");
out.print("<a href='?page="+(current-1)+"'>上一页</a>");
out.print(" 一共 "+pagesum+" 页");
out.print(" 当前页码是第 "+(current)+" 页 ");
out.println("<a href='?page="+(current+1)+"'>下一页</a>");
out.print(" <a href='?page="+pagesum+"'>尾页</a>");
}
}

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<%@ page language="java" import="java.util.*" pageEncoding="gbk"%>
<%@ taglib uri="http://java.sun.com/jstl/core_rt" prefix="c" %>
<%@ taglib uri="/WEB-INF/tag" prefix="p" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
This is my JSP page.
<%
pageContext.setAttribute("user",new Object());
Collection conn=new ArrayList();
conn.add(new String("KING"));
conn.add(new String("CAO"));
conn.add(new String("TOMCAT"));
conn.add(new String("LUCY"));
conn.add(new String("TOMCAT"));
conn.add(new String("LUCY"));
conn.add(new String("TOMCAT"));
conn.add(new String("LUCY"));
conn.add(new String("TOMCAT"));
conn.add(new String("LUCY"));
conn.add(new String("TOMCAT"));
conn.add(new String("反对法"));
conn.add(new String("反对福建卡"));
conn.add(new String("oorereoo"));
conn.add(new String("45rere6"));
conn.add(new String("12rere3"));
conn.add(new String("TOMCreAT"));
conn.add(new String("反对rrere法"));
conn.add(new String("反对福rerere建卡"));
conn.add(new String("ooorerereo"));
conn.add(new String("4rerere56"));
conn.add(new String("fdfddf"));
request.setAttribute("data",conn);
%>
<p:partition source="${requestScope.data}" result="a" currentPage="${param.page}" size="7"/>
<center >
<table border="1" cellpadding="5" cellspacing="1">
<c:forEach items="${a}" var="obj">
<tr><td>${obj}</td></tr>
</c:forEach>
<tr style="font-size: 13"><td><p:pagingLink/></td></tr>
</table>
</center>
</body>
</html>

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