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用Spring的JdbcTemplate实现分页功能

【IT168技术文档】最近使用了spring中的JdbcTemplate实现数据库的查询和插入操作,发现spring的JdbcTemplate 不象HibernateTemplate那么好,已经实现了分页功能。所以要自己实现,使用getJdbcTemplate().queryForList(string sql)得到的结果集是所有的。
  
  如果你的查询有10000条记录,或者更多,速度肯定慢了,当然你可以通过resultset中的游标控制查询的起始和结束。我这里用的是Oracle数据库,使用伪列ROWNUM来实现分页。我的分页代码如下:
package com.deity.ranking.util;import java.util.List;   import org.springframework.jdbc.core.JdbcTemplate;   import org.springframework.jdbc.core.support.JdbcDaoSupport;   /** * 分页函数 * * @author allenpan */public class Pagination extends JdbcDaoSupport{   public static final int NUMBERS_PER_PAGE = 10;   //一页显示的记录数   private int numPerPage;   //记录总数   private int totalRows;   //总页数   private int totalPages;   //当前页码   private int currentPage;   //起始行数   private int startIndex;   //结束行数   private int lastIndex;   //结果集存放List   private List resultList;   //JdbcTemplate jTemplate   private JdbcTemplate jTemplate;   /**   * 每页显示10条记录的构造函数,使用该函数必须先给Pagination设置currentPage,jTemplate初值   * @param sql oracle语句   */   public Pagination(String sql){   if(jTemplate == null){   throw new IllegalArgumentException("com.deity.ranking.util.Pagination.jTemplate is null,please initial it first. ");   }else if(sql.equals("")){   throw new IllegalArgumentException("com.deity.ranking.util.Pagination.sql is empty,please initial it first. ");   }   new Pagination(sql,currentPage,NUMBERS_PER_PAGE,jTemplate);   }   /**分页构造函数   * @param sql 根据传入的sql语句得到一些基本分页信息   * @param currentPage 当前页   * @param numPerPage 每页记录数   * @param jTemplate JdbcTemplate实例   */   public Pagination(String sql,int currentPage,int numPerPage,JdbcTemplate jTemplate){   if(jTemplate == null){   throw new IllegalArgumentException("com.deity.ranking.util.Pagination.jTemplate is null,please initial it first. ");   }else if(sql == null || sql.equals("")){   throw new IllegalArgumentException("com.deity.ranking.util.Pagination.sql is empty,please initial it first. ");   }   //设置每页显示记录数   setNumPerPage(numPerPage);   //设置要显示的页数   setCurrentPage(currentPage);   //计算总记录数   StringBuffer totalSQL = new StringBuffer(" SELECT count(*) FROM ( ");   totalSQL.append(sql);   totalSQL.append(" ) totalTable ");   //给JdbcTemplate赋值   setJdbcTemplate(jTemplate);   //总记录数   setTotalRows(getJdbcTemplate().queryForInt(totalSQL.toString()));   //计算总页数   setTotalPages();   //计算起始行数   setStartIndex();   //计算结束行数   setLastIndex();   System.out.println("lastIndex="+lastIndex);//////////////////   //构造oracle数据库的分页语句   StringBuffer paginationSQL = new StringBuffer(" SELECT * FROM ( ");   paginationSQL.append(" SELECT temp.* ,ROWNUM num FROM ( ");   paginationSQL.append(sql);   paginationSQL.append(" ) temp where ROWNUM <= " + lastIndex);   paginationSQL.append(" ) WHERE num > " + startIndex);   //装入结果集   setResultList(getJdbcTemplate().queryForList(paginationSQL.toString()));   }   /**   * @param args   */   public static void main(String[] args) {   // TODO Auto-generated method stub    }   public int getCurrentPage() {   return currentPage;   }   public void setCurrentPage(int currentPage) {   this.currentPage = currentPage;   }   public int getNumPerPage() {   return numPerPage;   }   public void setNumPerPage(int numPerPage) {   this.numPerPage = numPerPage;   }   public List getResultList() {   return resultList;    }   public void setResultList(List resultList) {   this.resultList = resultList;   }   public int getTotalPages() {   return totalPages;   }   //计算总页数   public void setTotalPages() {   if(totalRows % numPerPage == 0){   this.totalPages = totalRows / numPerPage;   }else{   this.totalPages = (totalRows / numPerPage) + 1;   }   }   public int getTotalRows() {   return totalRows;   }   public void setTotalRows(int totalRows) {   this.totalRows = totalRows;   }   public int getStartIndex() {   return startIndex;   }   public void setStartIndex() {   this.startIndex = (currentPage - 1) * numPerPage;   }   public int getLastIndex() {   return lastIndex;   }   public JdbcTemplate getJTemplate() {   return jTemplate;   }   public void setJTemplate(JdbcTemplate template) {   jTemplate = template;   }   //计算结束时候的索引   public void setLastIndex() {   System.out.println("totalRows="+totalRows);///////////   System.out.println("numPerPage="+numPerPage);///////////   if( totalRows < numPerPage){   this.lastIndex = totalRows;   }else if((totalRows % numPerPage == 0) || (totalRows % numPerPage != 0 && currentPage < totalPages)){   this.lastIndex = currentPage * numPerPage;   }else if(totalRows % numPerPage != 0 && currentPage == totalPages){//最后一页   this.lastIndex = totalRows ;   }   }}在我的业务逻辑代码中:   /**   * find season ranking list from DC   * @param areaId 选手区域id   * @param rankDate 赛季   * @param category 类别   * @param characterName 角色名   * @return List   */   public List findSeasonRankingList(Long areaId, int rankYear,int rankMonth,   Long categoryId,String characterName) {   //SQL语句   StringBuffer sql = new StringBuffer(" SELECT C.USERID userid,D.POSNAME posname,C.GAMEID gameid,C.AMOUNT amount,C.RANK rank FROM ");   //表            sql.append(" (SELECT B.USERID USERID,");   sql.append(" B.POSID POSID,");   sql.append(" A.DISTRICT_CODE DISTRICTCODE,");   sql.append(" A.GAMEID GAMEID,");   sql.append(" AMOUNT AMOUNT,");   sql.append(" RANK RANK ");   sql.append(" FROM TB_FS_RANK A ");   sql.append(" LEFT JOIN TB_CHARACTER_INFO B ");   sql.append(" ON A.DISTRICT_CODE = B.DISTRICT_CODE ");   sql.append(" AND A.GAMEID = B.GAMEID ");   //附加条件   if(areaId != null && areaId.intValue() != 0){   sql.append(" and A.DISTRICT_CODE = " + areaId.intValue());   }   if( rankYear > 1970 && rankMonth > 0){   //hql.append(" and sas.id.dt >= to_date('" + rankYear + "-" + rankMonth + "-01 00:00:00'," + "YYYY-MM-DD HH24:MI:SS");   //hql.append(" and sas.id.dt <= to_date('" + rankYear + "-" + rankMonth + "-" + TimeTool.findMaxDateInMonth(rankYear,rankMonth) + " 23:59:59'," + "YYYY-MM-DD HH24:MI:SS");   sql.append(" and A.DT = fn_time_convert(to_date('" + rankYear + "-" + rankMonth + "'," + "'YYYY-MM')) ");   }   if(categoryId != null && categoryId.intValue() != 0){   sql.append(" and A.CID = " + categoryId.intValue());   }   if(characterName != null && !characterName.trim().equals("")){   sql.append(" and A.GAMEID = '" + characterName.trim()+"' ");   }   sql.append(" ORDER BY RANK ASC) C ");   sql.append(" LEFT JOIN TB_FS_POSITION D ");   sql.append(" ON C.POSID = D.POSID ");   sql.append(" ORDER BY C.RANK ");   System.out.println("hql="+sql.toString());////////////////   //使用自己的分页程序控制结果集   Pagination pageInfo = new Pagination(sql.toString(),1,10,getJdbcTemplate());   return pageInfo.getResultList();   //return getJdbcTemplate().queryForList(sql.toString());   }
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