parameter query

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import jdbc.test.JdbcMySqlUtil;

public class InputOutputParameter {

 public static void main(String[] args) throws SQLException, ClassNotFoundException {
//  String sql = "insert into user (name,address) values (?,?)";
//  System.out.println(update(sql,new String[]{"testName","testAddress"}));
  
  String sql2 = "select * from user" ;
  List<Map<String,Object>> list = query(sql2);
  for (Map<String,Object> map:list)
  {
   for (String s:map.keySet())
    System.out.print(s +" ");
   for (Object obj:map.values())
    System.out.print(obj+" ");
   System.out.println();
  } 
 }
 
 private static int update(String sql,Object []args ) throws SQLException, ClassNotFoundException{
  PreparedStatement ps = JdbcMySqlUtil.getInstance().getPrepareStatement(sql);
  for (int i= 0 ; i < args.length ; i ++)
   ps.setObject(i+1, args[i]);
  int ret = ps.executeUpdate();
  JdbcMySqlUtil.free(null, ps, ps.getConnection());
  return ret ;
 }
 
 private static List<Map<String,Object>> query(String querySql) throws SQLException, ClassNotFoundException{
  Statement st = JdbcMySqlUtil.getInstance().getStatement() ;
  ResultSet rs = st.executeQuery(querySql);
  ResultSetMetaData rsm = rs.getMetaData();
  int colCount = rsm.getColumnCount();
  List<Map<String,Object>> list = new ArrayList<Map<String,Object>>();
  while(rs.next())
  {
   Map<String,Object> map = new HashMap<String,Object>();
   for (int i= 0 ; i < colCount ; i ++)
   {
    map.put(rsm.getColumnLabel(i+1), rs.getObject(i+1));
   }
   list.add(map);
  }
  JdbcMySqlUtil.free(rs, st, st.getConnection());
  return list ;
 }
}