JavaÐÅÏ¢Ìáʾ¿ò - Java / Java SE

private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
  Connection conn=DBUtil.getConnection();
  Statement stmt=null;
  try{
  stmt=conn.createStatement();
  String sql="select * from user";
  ResultSet rs = stmt.executeQuery(sql);
  while (rs.next()) {
if(jTextField1.getText().equals(rs.getString("username"))){ 
  JOptionPane.showMessageDialog(null,"¸ÃÓû§ÃûÒѾ­´æÔÚ£¬²»¿ÉÒÔʹÓá£");
  }else if(jTextField1.getText().equals("")){
  JOptionPane.showMessageDialog(null,"Óû§Ãû²»ÄÜΪ¿Õ£¬ÇëÖØÐÂÌîд£¡");
  }else if(!jTextField1.getText().equals(rs.getString("username"))){
  JOptionPane.showMessageDialog(null,"¸ÃÓû§Ãû²»´æÔÚ£¬¿ÉÒÔʹÓá£");
  }
  }

  }catch(SQLException e){
  e.printStackTrace();
  }finally{
  try{
  stmt.close();
  DBUtil.close(conn);
  }catch(SQLException e){
  e.printStackTrace();
  }
  }
  }
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