去掉这一行的参数:

rs= pst.executeQuery(query);

一定是

rs= pst.executeQuery();

因为语句是在PreparedStatement pst=conn.prepareStatement(query);

execute(String sql) 继承自 语句 并且会在没有准备好的情况下执行语句(sql).

execute(String sql) is inherited from Statement and will execute the satement (sql) without prepared it.