1、添加网络访问权限
<uses-permission android:name="android.permission.INTERNET" />
developer官方文档关于html5支持视频播放描述如下：In order to support inline HTML5 video in your application, you need to have hardware acceleration turned on, and set a WebChromeClient.
For full screen support, implementations of onShowCustomView(View,
WebChromeClient.CustomViewCallback) and onHideCustomView() are
required, getVideoLoadingProgressView() is
optional.
1）开启硬件加速
2）重写WebChromeClient的onShowCustomView(View,
WebChromeClient.CustomViewCallback)和onHideCustomView()
通过onShowcustomView对大屏的布局进行加载，隐藏小屏布局；在onHideCustomeView中退出全屏播放，重新显示小屏布局
参考：
http://developer.android.com/reference/android/webkit/WebView.html