网上商城--登陆验证

自定义异常

public class UserNotFoundException extendsRuntimeException

{

   public UserNotFoundException (String message){  //构造方法

       super(message);

  }

}

public static User check (String username, String password) throws UserNotFoundException, PassworkNotCOrrectException

{

  User u = null;

 Connection conn = DB.getConn();

String sql = "select * from user where username = ' '"+username+" ' ";

Statement stmt = DB.getStatement(conn);

ResultSet  rs = DB.getResultSet(stmt , sql);

try{

 if( !  rs.next() ){

    throw new UserNotFoundException("用户不存在："＋username);

}else{

 if(! password.equals(rs.getString(" password ")){

     throw new PasswordNotCorrectionException("密码输入不正确！ ");

}

u = new User();

u.setId ( rs . getInt (" id ") );

...

}catch(SQLExeption e){

  e.printStackTrace();

}finally

{

DB.close(rs);

DB.close(stmt);

DB.close(conn);

}

return u;

}