PaginationSupport加强版的分页代码

PaginationSupport.java,这个类网上有，我把它加强了一下，看下面

import java.util.ArrayList;
import java.util.List;

public class PaginationSupport {
	public static int PAGESIZE = 10;

	private int pageSize = PAGESIZE;

	private List items;

	private int totalCount;

	private int[] indexes = new int[0];

	private int startIndex = 0;
	
	private int lastStartIndex;
	
	public PaginationSupport(){
	}

	public PaginationSupport(List items, int totalCount) {
		setPageSize(PAGESIZE);
		setTotalCount(totalCount);
		setItems(items);
		setStartIndex(0);
	}

	public PaginationSupport(List items, int totalCount, int startIndex) {
		setPageSize(PAGESIZE);
		setTotalCount(totalCount);
		setItems(items);
		setStartIndex(startIndex);
	}

	public PaginationSupport(List items, int totalCount, int pageSize,
			int startIndex) {
		setPageSize(pageSize);
		setTotalCount(totalCount);
		setItems(items);
		setStartIndex(startIndex);
	}

	public List getItems() {
		return items;
	}

	public void setItems(List items) {
		this.items = items;
	}

	public int getPageSize() {
		return pageSize;
	}

	public void setPageSize(int pageSize) {
		this.pageSize = pageSize;
	}

	public int getTotalCount() {
		return totalCount;
	}

	public void setTotalCount(int totalCount) {
		if (totalCount > 0) {
			this.totalCount = totalCount;
			int count = totalCount / pageSize;
			if (totalCount % pageSize > 0)
				count++;
			indexes = new int[count];
			for (int i = 0; i < count; i++) {
				indexes[i] = pageSize * i;
			}
		} else {
			this.totalCount = 0;
		}
	}

	public int[] getIndexes() {
		return indexes;
	}

	public void setIndexes(int[] indexes) {
		this.indexes = indexes;
	}

	public int getStartIndex() {
		return startIndex;
	}

	public void setStartIndex(int startIndex) {
		if (totalCount <= 0)
			this.startIndex = 0;
		else if (startIndex >= totalCount)
			this.startIndex = indexes[indexes.length - 1];
		else if (startIndex < 0)
			this.startIndex = 0;
		else {
			this.startIndex = indexes[startIndex / pageSize];
		}
	}

	public int getNextIndex() {
		int nextIndex = getStartIndex() + pageSize;
		if (nextIndex >= totalCount)
			return getStartIndex();
		else
			return nextIndex;
	}

	public int getPreviousIndex() {
		int previousIndex = getStartIndex() - pageSize;
		if (previousIndex < 0)
			return 0;
		else
			return previousIndex;
	}
	
	public int getLastIndex(){
		int[] indexes = this.getIndexes();
		if(indexes != null && indexes.length >0){
			lastStartIndex = indexes[indexes.length-1];
		}
		return lastStartIndex;
		
	}
	
//	一共多少页
	public int getPages(){
		if(getTotalCount()%pageSize==0){
			return getTotalCount()/pageSize;
		}
		return (getTotalCount()/pageSize)+1;
	}
	//当前第几页
	public int getCurrentPage(){
		return (getStartIndex()/pageSize)+1;
	}
	
//感谢dengyin2000提供如下算法
	/**
	 * 记录显示的页码组
	 * @param totalPages
	 * @param currentPage
	 * @return
	 */
	public ArrayList<Integer> page(int totalPages, int currentPage) {  
		int adjacents = 3;//这个参数可以调ArrayList的长度，试试就知道了
		ArrayList<Integer> result = new ArrayList<Integer>();  
		if (totalPages < (5 + (adjacents * 2))){ // not enough links to make it worth breaking up  
		    writeNumberedLinks(1, totalPages, result);  
		    }else{
			  if ((totalPages - (adjacents * 2) > currentPage) && (currentPage > (adjacents * 2))){ // in the middle  
				  writeNumberedLinks(1, 1, result);  
				  writeElipsis(result);  
				  writeNumberedLinks(currentPage - adjacents - 1, currentPage + adjacents, result);  
				  writeElipsis(result);  
				  writeNumberedLinks(totalPages, totalPages, result);  
			  }else if (currentPage < (totalPages / 2)){
				  writeNumberedLinks(1, 3 + (adjacents * 2), result);  
				  writeElipsis(result);  
				  writeNumberedLinks(totalPages, totalPages, result);  
			  }else{ // at the end  
		            writeNumberedLinks(1, 1, result);  
		            writeElipsis(result);  
		            writeNumberedLinks(totalPages - (2 + (adjacents * 2)), totalPages, result);  
			      }  
			  }  
		 return result;  
	}  
		  
	  /** 
	  * @param result  
	  *  
	  */  
	  private void writeElipsis(ArrayList<Integer> result) {  
		  result.add(-1);//-1是用来打点的
	  }
		   
	  /** 
	  * @param i 
	  * @param lastIndex 
	  * @param result  
	  */  
	private void writeNumberedLinks(int i, int lastIndex, ArrayList<Integer> result) {  
		for (int d=i; d <= lastIndex; d++) {  
		  result.add(d);  
		}
	}    

}

在jsp中的用法：

<%@ page contentType="text/html; charset=UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> 
 <html:hidden property="startIndex"/>
<table width="100%" border="0" cellpadding="2" cellspacing="0" bordercolor="#4DB0E7" class="TableMain">
  <tr bgcolor="#FFFFFF">
    <td width="17%">总记录 ${ requestScope.pagination.totalCount } 条 
   	<input title="首页" class="menuList" name="1" type="submit" onClick="this.document.forms[0].startIndex.value='0';" value="首  页">
   	<input title="上一页" class="menuList" name="1" type="submit" onClick="this.document.forms[0].startIndex.value=${ requestScope.pagination.previousIndex };" value="上一页">
   	<c:forEach var="i" items="${requestScope.pages}">
   		<c:choose>
   			<c:when test="${i==-1}" >
   				...
   			</c:when>
   			<c:when test="${i==requestScope.pagination.currentPage}" >
   				<a href="userManage.portal?action=listUser&page=${ i }"  target="mainFrame" style="color:red;">${ i }</a>
   			</c:when>
   			<c:otherwise>
   				<a href="userManage.portal?action=listUser&page=${ i }"  target="mainFrame" >${ i }</a>
   			</c:otherwise>
   		</c:choose>
   	</c:forEach>
   	<input title="下一页" class="menuList" name="1" type="submit" onClick="this.document.forms[0].startIndex.value=${ requestScope.pagination.nextIndex };" value="下一页">
   	<input title="尾页" class="menuList" name="1" type="submit" onClick="this.document.forms[0].startIndex.value=${ requestScope.pagination.lastIndex };" value="尾页">
   	共有${ requestScope.pagination.pages }页，当前是第${ requestScope.pagination.currentPage }页
    </td>
  </tr>
</table>

上面的首页，上一页，下一页，尾页我使用了submit提交，其实也可以用<a href="...">
只是我一开始做的时候只有首页，上一页，下一页，尾页四个button，没有考虑中间的1，2，3，4，5，6....所以有些混乱，勉强看吧。
下面的是在action中用法：

String action=request.getParameter("action");
if("listUser".equals(action)){
String page=request.getParameter("page");			
	if(page!=null){
		int p=Integer.parseInt(page);
		form.setStartIndex((p-1)*Constant.PAGESIZE);//p总是从1开始，但记录从0开始，所以p-1
	}
	PaginationSupport pagination=this.getBaseService().findPageByCriteria(detachedCriteria, Constant.PAGESIZE, form.getStartIndex());//该方法网上有，查一下
	List list = pagination.getItems();
	request.setAttribute("list", list);
	request.setAttribute("pagination", pagination);
	request.setAttribute("pages", pagination.page(pagination.getPages(), pagination.getCurrentPage()));
	return mapping.findForward("listUser");
}

这里要传递的是startIndex的值，所以form中需要定义int startIndex的getter，setter

这个分页我个人认为比较好了，代码比较优美。
类似如下效果：
总记录 108 条 首页 上一页  1 2 3 4 5 ...10 下一页 尾页   共有10页，当前是第1页