自定义ProgressDialog

http://blog.csdn.net/rohsuton/article/details/7518031
这里你可以换成单图片旋转也行。

调整对话框背景透明度

// 显示透明的对话框   
4.    AlertDialog alertDialog = new AlertDialog.Builder(this).setMessage(   
5.            "透明对话框").setPositiveButton("确定", null).create();   
6.    Window window = alertDialog.getWindow();   
7.    WindowManager.LayoutParams lp = window.getAttributes();   
8.    // 设置透明度为0.3     An alpha of 1.0 means fully opaque and 0.0 means fully transparent
9.    lp.alpha = 0.6f;   
//黑暗度为  Range is from 1.0 for completely opaque to 0.0 for no dim.
lp.dimAmount=1.0f;
10.    window.setAttributes(lp);   
11.    alertDialog.show();   

调整对话框位置

      AlertDialog dialog = new AlertDialog.Builder(this).setTitle("title")
                           .setMessage("message").create();
      Window window = alertDialog.getWindow();   
      window.setGravity(Gravity.TOP);   //window.setGravity(Gravity.BOTTOM);
      alertDialog.show();