public <T> QueryResult<T> getScrollData(Class<T> entityClass,String wherejpql,Object[] queryParams,
   int firstindex, int maxResult, LinkedHashMap<String, String> orderby) {
//  for(int i = 0;i<queryParams.length;i++){
//   System.out.println("=================queryParams is " + i +queryParams[i]);
//  }
  String entityName = getEntityName(entityClass);
  QueryResult qr = new QueryResult<T>();

  String sql = "select o from "+entityName+" o " + (wherejpql==null?"":"where " + wherejpql) + buildOrderby(orderby);
  Query query = em.createQuery(sql);
  setQueryParams(query,queryParams);
  System.out.println("-------------------in DaoSupport :sql is:" + sql);
  /**
   * 1：查詢的時候第一步查詢到的都是資料表裡所有的記錄
   * 2：再用query.setFirstResult(firstindex).setMaxResults(maxResult)
   * 方法來設定要顯示的首記錄（即從哪一條開始顯示）和要顯示的記錄條數
   * 3：然後儲存相關資料，方便前臺頁面顯示
   */
  if(firstindex != -1 && maxResult != -1){
   query.setFirstResult(firstindex).setMaxResults(maxResult);
  }
  
  
  qr.setResultList(query.getResultList());
  /**
   * 這裡的記錄數不是要顯示的記錄有多少條，而是資料表裡一共有多少條記錄
   */
  query = em.createQuery("select count(o) from "+entityName+" o " + (wherejpql==null?"":"where " + wherejpql));
  
   setQueryParams(query,queryParams);
  
  qr.setTotalrecord((Long)query.getSingleResult());
  return qr;
 }

 /**
  * 構建order by 語句
  * orderby 語句格式：order by key1 asc,key2 asc
  * @param orderby
  * @return
  */
 protected String buildOrderby(LinkedHashMap<String, String> orderby){
  StringBuffer orderbySql = new StringBuffer("");
  if(orderby !=null && orderby.size()>0){
   orderbySql.append(" order by ");
   //order by key1 desc,key2 asc
   for(String key:orderby.keySet()){
    orderbySql.append(key).append(" ").append(orderby.get(key)).append(",");
   }
   orderbySql.deleteCharAt(orderbySql.length() - 1);
  }
  return orderbySql.toString();
 }

/**
  * 給where語句設定引數值
  * wherejpql 語句格式：where o.property=?1,o.property=?2。
  * @param query
  * @param params
  */
 protected void setQueryParams(Query query,Object[] params){
  if(params != null && params.length > 0){
   for(int i=0;i<params.length;i++){
    //System.out.println("i+1 = " + (i+1) + " params[i] " + params[i] );
    query.setParameter(i+1, params[i]);
   }
  }
 }

QueryResult.java:

package com.itcast.util;

import java.util.List;

public class QueryResult<T>{
 private List<T> resultList;
 private long totalrecord;
 public List<T> getResultList() {
  return resultList;
 }
 public void setResultList(List<T> resultList) {
  this.resultList = resultList;
 }
 public long getTotalrecord() {
  return totalrecord;
 }
 public void setTotalrecord(long totalrecord) {
  this.totalrecord = totalrecord;
 }

}