builder的theme如此设置就行了
// 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
9. lp.alpha = 0.6f;
10. window.setAttributes(lp);
11. alertDialog.show();
不用alertDialog,可以尝试使用Dialog