javabean使用有问题 各位大侠帮忙！烦死我了!

ConnectDB

package bbs;

import java.lang.*;
import java.sql.*;

public class ConnectDB {
  String url="jdbc:odbc:bbs";
  Connection dbConn;
  String errMes;
  public ConnectDB()
  {
  errMes="";
  dbConn=null;
  }
  public Connection getConn()
  {
  try{
  Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
  dbConn=DriverManager.getConnection("jdbc:odbc:bbs","sa","");
  }catch(Exception e){
  System.out.print(e);
  }
  return dbConn;
  }
  public String getErrMes()
  {
  return errMes;
  }
}

package bbs;

import java.lang.*;
import java.sql.*;

public class ExecuteDB extends ConnectDB {
  private Connection dbConn;
  private Statement stmt;
  private ResultSet rs;
  private String errMes;
  public ExecuteDB() {
  dbConn=super.getConn();
  stmt=null;
  rs=null;
  this.errMes=super.getErrMes();
  }
  public boolean exeSql(String strSql)
  {
  boolean isSuc=false;
  try
  {
  stmt=dbConn.createStatement();
  stmt.executeUpdate(strSql);
  stmt.close();
  isSuc=true;
  }
  catch(Exception e)
  {
  this.errMes=this.errMes+"<br>"+e.toString();
  }
  return isSuc;
  }
  public ResultSet exeQuery(String strSql)
  {
  try
  {
  stmt=dbConn.createStatement();
  rs=stmt.executeQuery(strSql);
  }
  catch(Exception e)
  {
  this.errMes=this.errMes+"<br>"+e.toString();
  rs=null;
  }
  return rs;
  }
  public String getErrMes()
  {
  return errMes;
  }
}

package bbs;

import java.sql.*;

public class User extends ExecuteDB{
  private long UserID;
  private String UserName;
  private String UserPassword;
  private String Email;
  private String Sex;
  private String NickName;
  private String CreateTime;
  private String Role;
  private String strSql;
  public User()
  {
  super();
  this.UserID=0;
  this.UserName="";
  this.UserPassword="";
  this.Sex="";
  this.NickName="";
  this.Role="0";
  this.Email="";
  java.util.Date NowTime=new java.util.Date();
  this.CreateTime=NowTime.toString();
  this.strSql="";
  }
  public void setUserName(String name)
  {
  this.UserName=name;
  }
  public void setUserPassword(String password)
  {
  this.UserPassword=password;
  }
  public void setSex(String sex)
  {
  this.Sex=