android中文字跑马灯效果

<TextView      android:layout_width="fill_parent"     android:layout_height="wrap_content"     android:padding="10dip"    android:text="这是跑马灯呀啊啊啊啊 啊啊啊啊啊 啊！"    android:textSize = "22sp"      android:textColor="#000000"      android:singleLine="true"     android:ellipsize="marquee"      android:marqueeRepeatLimit="marquee_forever"     android:focusable="true"      android:selectAllOnFocus="true"      android:clickable="true"    android:background="#ffffff"    android:focusableInTouchMode="true"     android:freezesText="true"  >    <requestFocus/>    </TextView>