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38 lines
1.9 KiB
38 lines
1.9 KiB
7 months ago
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There are two libraries defined in this directory:
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First, com.android.mediadrm.signer.jar is a shared java library
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containing classes required by unbundled apps running on devices that use
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the certficate provisioning and private key signing capabilities provided
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by the MediaDrm API.
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Second, com.android.mediadrm.signer.stubs.jar is a stub for the shared library
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which provides build-time APIs to the unbundled clients.
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At runtime, the shared library is added to the classloader of the app via the
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<uses-library> tag. And since Java always tries to load a class from the
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parent classloader, regardless of whether the stub library is linked to the
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app statically or dynamically, the real classes are loaded from the shared
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library.
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--- Rules of this library ---
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o The stub library is effectively a PUBLIC API for unbundled CAST receivers
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that may be distributed outside the system image. So it MUST BE API STABLE.
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You can add but not remove. The rules are the same as for the
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public platform SDK API.
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o This library can see and instantiate internal platform classes, but it must not
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expose them in any public method (or by extending them via inheritance). This would
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break clients of the library because they cannot see the internal platform classes.
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This library is distributed in the system image, and loaded as
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a shared library. So you can change the implementation, but not
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the interface. In this way it is like framework.jar.
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--- Why does this library exist? ---
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Unbundled apps cannot use internal platform classes.
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This library will eventually be replaced when the provisioned certificate-
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based signing infrastructure that is currently defined in the support library
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is reintegrated with the framework in a new API. That API isn't ready yet so
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this library is a compromise to make new capabilities available to the system
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without exposing the full surface area of the support library.
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