如何处理 JOptionPane 中的取消按钮

I had created a JOptionPane of type showInputDialog. When it opens it, it shows me two buttons: OK and Cancel. I would like to handle the action when I push on Cancel button, but I don't know how to reach it. How can I get it?

例如：

int n = JOptionPane.showConfirmDialog(
                            frame, "Would you like green eggs and ham?",
                            "An Inane Question",
                            JOptionPane.YES_NO_OPTION);
if (n == JOptionPane.YES_OPTION) {

} else if (n == JOptionPane.NO_OPTION) {

} else {

}

或者用showOptionDialog:

Object[] options = {"Yes, please", "No way!"};
int n = JOptionPane.showOptionDialog(frame,
                "Would you like green eggs and ham?",
                "A Silly Question",
                JOptionPane.YES_NO_OPTION,
                JOptionPane.QUESTION_MESSAGE,
                null,
                options,
                options[0]);
if (n == JOptionPane.YES_OPTION) {

} else if (n == JOptionPane.NO_OPTION) {

} else {

}

See 如何制作对话框 http://docs.oracle.com/javase/tutorial/uiswing/components/dialog.html更多细节。

EDIT: showInputDialog

String response = JOptionPane.showInputDialog(owner, "Input:", "");
if ((response != null) && (response.length() > 0)) {

}