ContentLoadingProgressBar

Android5.0之后推出一系列的新组件 ContentLoadingProgressBar 也是其中一个 

java.lang.Object
↳	android.view.View
	↳	android.widget.ProgressBar
		↳	android.support.v4.widget.ContentLoadingProgressBar

从层级关系可以看出他是直接继承ProgressBar的父类。在ProgressBar的基础上衍生了自己的共有方法

（1）contentLoadingProgressBar.hide()官方给出的解释 Hide the progress view if it is visible.

（2）contentLoadingProgressBar.show() Show the progress view after waiting for a minimum delay.

（3）contentLoadingProgressBar.onAttachedToWindow(); This is called when the view is attached to a window. 

（4）contentLoadingProgressBar.onDetachedFromWindow() This is called when the view is detached from a window.

等等。在progressbar的基础上优化了好多。他的布局也是很简单。

<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" >

    <android.support.v4.widget.ContentLoadingProgressBar
        android:id="@+id/progress"
        style="?android:attr/progressBarStyleLarge"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

LinearLayout>