Android AlertDialog全局显示

AlertDialog dialog=new AlertDialog.Builder(context.getApplicationContext())
        .setTitle(title)
        .setMessage(message)
        .setNegativeButton("取消", null)
        .setPositiveButton("确定", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {
            }
        }).create();
dialog.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);
dialog.show();

权限：
<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />

只是怕忘了记个笔记