参考资料:
1. Android自定义类似ProgressDialog效果的Dialog
http://blog.csdn.net/qjlhlh/article/details/7979179
2. 花样Android ProgressBar 史上最强大讲解
http://www.eoeandroid.com/thread-1081-1-1.html
3. Android ProgressBar自定义图片进度,自定义渐变色进度条
http://my.oschina.net/amigos/blog/59871
4. android圆形进度条ProgressBar颜色设置
http://www.eoeandroid.com/thread-182514-1-1.html
5. android界面的美化shape的使用
http://blog.csdn.net/dblackde/article/details/7370467
6. 两种android loading效果(帧动画和ProgressDialog)
http://blog.csdn.net/zhuqiang1002/article/details/7444272