Make MimeMap final and introduce MimeMap.Builder.
This CL topic introduces a new @CorePlatformApi MimeMap.Builder
and uses it to make MimeMap a concrete, final, immutable type.
This has the following advantages:
- Consistency of behavior of MimeMap implementations with regards
to lower-casing and treatment of null is trivial to guarantee
because there is only one implementation.
- The @CorePlatformApi surface now makes more sense. The responsibility
for lower-casing and treatment of null was previously split between
MimeMap in libcore and MimeMapImpl in frameworks/base, which is why
MimeMap.toLowerCase() and MimeMap.isNullOrEmpty() were in the
@CorePlatformApi.
- Most of the logic now lives in libcore / ART module.
frameworks/base now has minimal logic. This makes it easier to write
(in a follow-up CL) a CTS test that asserts all the default mappings,
because that test can now duplicate that small amount of logic in
order to read from a copy of the same data files.
Note: The semantics of the @CorePlatformApi Builder.put(String, List<String>)
are fairly complex, which isn't great. This was done because:
- By following the semantics of the *mime.types file format, it allows
us to minimize the logic in frameworks/base.
- It's simpler than having multiple overloads of put() for
mimeType -> file extension mapping and vice versa,
and for whether or not any existing mapping should be overwritten.
If we had named classes for MimeType and FileExtension with
appropriate case-insensitive equals and hashCode semantics, then
we could instead have API such as
builder.asMimeToExtensionMap().put(...)
but existing API (e.g. Intent.getType(), android.webkit.MimeTypeMap)
has set precedent for treating these as Strings.
Bug: 136256059
Test: atest CtsLibcoreTestCases
Test: atest CtsMimeMapTestCases
Change-Id: Ie00ba8a89fe1429b9b8f986bd9a0da196862426c
3 files changed