原因：原因是不同的控件高低层次不同，遮挡了显示
解决方法：将android:clipChildren置为"false"。android:clipChildren=“false”
有多个父控件存在时全把android:clipChildren置为"false"
例如(带星号部分)：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@mipmap/remote_background">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:clipChildren="false"//**************************************
android:orientation="vertical">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1.7">
</RelativeLayout>
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:clipChildren="false"//**************************************
android:layout_weight="1">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:clipChildren="false"//**************************************
android:orientation="horizontal">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1">
<ImageView
android:id="@+id/position"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:clipChildren="false"//**************************************
android:background="@mipmap/remote_speed_hand"/>
</RelativeLayout>
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1.02">
</RelativeLayout>
</LinearLayout>
</RelativeLayout>
</LinearLayout>
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="ddd"/>
</RelativeLayout>
