的角色 <uses-permission> 清单文件中标记？

Question

I am new to Android development and I have been using the < uses-permission > tag in some of my previous applications. However, I am still in the dark as to how the tag actually works. I understand that the tag ensures that Android sign a 'contract' such that only the components part of the key-value pairs in the tag are included in an application. My question specifically is:

Q. How do the key-value attributes of < uses-permission > tag impart the 'information' that Android requires to restrict an app from including features not mentioned in the tag's key-value pair?

My internet searches have not given me the answer I was looking for and any direction on this would be most appreciated.

Answer 1

The permissions listed in that tag are presented to the user at install time. Thus the user is forced to explicitly grant those permissions or not (by terminating the install).

Answer 2

A permission is a restriction limiting access to a part of the code or to data on the device. The limitation is imposed to protect critical data and code that could be misused to distort or damage the user experience.

Requests a permission that the application must be granted in order for it to operate correctly. Permissions are granted by the user when the application is installed, not while it's running.

For more info see uses-permission

Answer 3

The official docs explain how it works:

To make use of the protected APIs on the device, an application must define the capabilities it needs in its manifest. When preparing to install an application, the system displays a dialog to the user that indicates the permissions requested and asks whether to continue the installation. If the user continues with the installation, the system accepts that the user has granted all of the requested permissions. The user can not grant or deny individual permissions -- the user must grant or deny all of the requested permissions as a block.

Once granted, the permissions are applied to the application as long as it is installed. To avoid user confusion, the system does not notify the user again of the permissions granted to the application, and applications that are included in the core operating system or bundled by an OEM do not request permissions from the user. Permissions are removed if an application is uninstalled, so a subsequent re-installation will again result in display of permissions.

In the event that an application attempts to use a protected feature which has not been declared in the application's manifest, the permission failure will typically result in a security exception being thrown back to the application. Protected API permission checks are enforced at the lowest possible level to prevent circumvention.