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