在xml文件中，edittext這個控件設置了，android：focusable=“false”，
在代碼中edittext.setfocusable(true),edittext這個控件仍然無法點擊，百度之後，得到的結果是：
一定要按一下這個順序寫，重新使edittext獲取焦點：
edittext.setFocusable(true);
edittext.setFocusableInTouchMode(true);
edittext.requestFocus();
edittext.requestFocusFromTouch();
這是爲什麼呢？
查閱API：
setFocusable(boolean):
Set whether this view can receive the focus. Setting this to false will also ensure that this view is not focusable in touch mode.
//--設置edittext是否可以獲得焦點
setFocusableInTouchMode(boolean):
Set whether this view can receive focus while in touch mode. Setting this to true will also ensure that this view is focusable.
//--設置edittext在touch模式下是否可以獲得焦點
requestFocus():
Call this to try to give focus to a specific view or to one of its descendants. A view will not actually take focus if it is not focusable (isFocusable() returns false), or if it is focusable and it is not focusable
in touch mode (isFocusableInTouchMode()) while the device is in touch mode.
//--調用這個給指定的view或者它的子view焦點。如果這個view在isFocusable()方法下返回false，或者isFocusableInTouchMode()方法下返回false，這個view不會真正獲得焦點
requestFocusFromTouch():
Call this to try to give focus to a specific view or to one of its descendants. This is a special variant of
requestFocus() that will allow views that are not focuable in touch mode to request focus when they are touched.
//--調用這個給指定的view或者它的子view焦點。這個特別的變異於（？）requestFocus（）的方法會讓在這個view被touch時，給view焦點。
以上。