mDialog = new ProgressDialog(this);
mDialog.setCancelable(true);//是否可以被取消
mDialog.setMessage("loading...");//加载显示的信息
mDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);//圆环风格
mDialog.show();

mDialog = new ProgressDialog(this);
mDialog.setCancelable(true);//是否可以被取消
mDialog.setMessage("loading...");//加载显示的信息
mDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);//圆环风格
mDialog.show();

mDialog.setContentView(R.layout.view_progress);//自定义布局

//注意：setContentView()要在show()后使用

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:gravity="center_vertical"
 android:padding="10dp"
 android:orientation="horizontal">

 <ProgressBar
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:indeterminateDrawable="@drawable/progress_black" />

 <TextView
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="loading..." />
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<animated-rotate xmlns:android="http://schemas.android.com/apk/res/android"
 android:drawable="@drawable/loading_ball"
 android:fromDegrees="0"
 android:pivotX="50.0%"
 android:pivotY="50.0%"
 android:toDegrees="360" />