JDK doc描述
* Moves the cursor froward one row from its current position.
* A <code>ResultSet</code> cursor is initially positioned
* before the first row; the first call to the method
* <code>next</code> makes the first row the current row; the
* second call makes the second row the current row, and so on.
从当前游标位置向前移动一行,ResultSet游标初始化位置被置于第一行之前;第一次调用next方法使游标移动到第一行。
第一次调用将使游标移动到第二行,依次类推。
/**
* Moves the cursor to the last row in
* this <code>ResultSet</code> object.
移动游标到ResultSet对象的最后一行