Anfroid 在界面中显示图片 ImageView

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent" 
    android:orientation="vertical"
    >

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:src="@drawable/ic_lena" 
        android:background="#00FFFF"
        />
    
    <ImageView
        android:id="@+id/imageView2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@drawable/ic_lena" />
    
    <ImageView
        android:id="@+id/imageView3"
        android:layout_width="match_parent"
        android:layout_height="30dp"
        android:background="#00FFFF" />

    <ImageView
        android:id="@+id/imageView3"
        android:layout_width="200dp"
        android:layout_height="200dp"
        android:background="@drawable/ic_lena" />
    
</LinearLayout>