java - 检索权限描述返回 'null'

Question

为了获取权限的描述。我使用了以下代码:

    PackageManager packageManager = this.getPackageManager();
    long time = System.currentTimeMillis();
    PermissionInfo pinfo = null;
    try {
        pinfo = packageManager.getPermissionInfo("android.permission.BODY_SENSORS", PackageManager.GET_META_DATA);
        if(pinfo != null) Log.i("permissions","pInfo not null???????????????????????????????????????");
        Log.i("permissions ",  pinfo.loadDescription(packageManager)  + " *** "  + pinfo.group);
    } catch (PackageManager.NameNotFoundException e) {
            e.printStackTrace();
    }
    time = System.currentTimeMillis() - time;

但是对于某些权限，例如 - android.permission.BATTERY_STATS，当我调用 pinfo 时，我有一个 null char 序列.loadDescription(packageManager)。我不明白为什么？我也在努力寻找原因，但没有办法找到。有哪位android专家可以帮我解释一下吗？

Answer 1

I have a null CharSequence when I call pinfo.loadDescription(packageManager).I don't understand why?

因为 Google 选择不提供该权限的说明(或标题)。对于许多签名级权限来说都是如此。您可以检查the AOSP edition of the framework manifest了解您可以期待什么。