android中设置控件获得焦点

android中，要使控件获得焦点，需要先setFocus,再requestFocus。

以Button为例：

btn.setFocusable(true);

btn.setFocusableInTouchMode(true);

btn.requestFocus();

btn.requestFocusFromTouch();

//获得失去焦点的监听器

btn.setOnFocusChangeListener(new OnFocusChangeListener() {

@Override

public void onFocusChange(View v, boolean hasFocus) {

// TODO Auto-generated method stub

if (hasFocus) {

btn_box.setBackgroundResource(R.drawable.book_green);

}else {

btn_box.setBackgroundResource(R.drawable.book);

}

}

});

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