让SWT中的text只能输入数字

思路：给Text添加键盘输入事件，判断按下的键的ASCII码
代码如下：

text = new Text(group_3, SWT.BORDER);
		text.addKeyListener(new KeyAdapter() {
			public void keyPressed(final KeyEvent e) {
				if (!Converts.checkDate(e.keyCode)) {
					e.doit = false;
				}
			}
		});


public static boolean checkDate(int n) {
		if (48 == n || 49 == n || 50 == n || 51 == n || 52 == n || 53 == n || 54 == n
				|| 55 == n || 56 == n || 57 == n) {
			return true;
		}
		return false;
	}