dbutil.java

java数据库操作工具类

package com.baosight.util;

import java.sql.ResultSet;
import java.util.HashMap;
import java.util.List;

/**
 * 操作数据库的工具类
 * @author steven
 * @version 2005-2-2
 */
public class DBUtil {

    /**
     * 执行更新操作
     * @param sp
     * @param ps
     */
    public static int executeUpdate(String sql, HashMap ps) {
    	//sql= SqlUtil.makeSimpleSql(sql,ps);
        EntityManager em = new EntityManager();
        return em.executeUpdate(sql,ps);
    }
    /**
     * 执行更新操作
     * @param sp
     * @param ps
     */
    public static int executeUpdate(String sql) {
        EntityManager em = new EntityManager();
        return em.executeUpdate(sql);
    }

    /**
     * 执行查询操作，查询结果只有一个字段和一条记录，并转换为int
     * @param sp
     * @param ps
     * @return
     */
    public static int getInt(String sp) {
        EntityManager em = new EntityManager();
        Integer rs = (Integer) em.loadObject(sp,
                new ResultSetHandler() {
            		public Object processRow(ResultSet rs) throws Exception {
            		    return new Integer(rs.getInt(1));
            		}
        		}
        );
        return rs.intValue();
    }

    /**
     * 执行查询操作，查询结果只有一个字段和一条记录，并转换为float
     * @param sp
     * @param ps
     * @return
     */
    public static Float getFloat(String sp) {
        EntityManager em = new EntityManager();
        Float rs = (Float) em.loadObject(sp,
                new ResultSetHandler() {
            		public Object processRow(ResultSet rs) throws Exception {
            		    return new Float(rs.getFloat(1));
            		}
        		}
        );
        return rs;
    }

    public static int getCount(String sql) {
    	String countSql = "select count(*) from ( " + sql + " )";
        EntityManager em = new EntityManager();

        Integer rs = (Integer) em.loadObject(countSql,
                new ResultSetHandler() {
            		public Object processRow(ResultSet rs) throws Exception {
            		    return new Integer(rs.getInt(1));
            		}
        		}
        );

        return rs.intValue();
    }

   public static List query(String sp,String className) {
       DefaultQueryHandler qh = new DefaultQueryHandler(className);
       EntityManager em = new EntityManager();
       return em.executeQuery(sp,qh);
   }

  public static List query(String sp) {
      HashMapHandler qh = new HashMapHandler();
      EntityManager em = new EntityManager();
      return em.executeQuery(sp,qh);
  }

  public static List query(String sql,ResultSetHandler handler) {
      EntityManager em = new EntityManager();
      return em.executeQuery(sql,handler);
  }

  public static List query(String sql,int page,int length){
	  int begin  = (page-1)*length;
	  int end = page*length;
	  String qs =" SELECT * FROM ( SELECT row_.*, ROWNUM rownum_ FROM ( "
			     + sql
			     + " ) row_ WHERE ROWNUM <= " + end + ") WHERE rownum_ >" +begin;
	 return query(qs);
  }

  public static List pageQuery(String sql,String current_page,int length){
	  if( current_page== null ){
		  current_page = "1";
	  }
		if( current_page.length()==0 ) {
			current_page = "1";
		}
	  int page =1;
	  try{
		  page= new Integer(current_page).intValue();
	  }catch(Exception e){

	  }

	  return query(sql,page,length);
  }

   public String makeQuerySql(String sql,HashMap paras){
	   String result=null;
	   if( sql.indexOf("where")<0 ) {
		   result = sql + " where ";
	   }

	   return result;
   }
}