14.12.2010 11:36, Mark Carter пишет:
I think there is a problem there because you are setting AUTHORITY
from the constructor and so there is a chance it has not been set
when Uri.ParseUri("content://" +
CommonContentProviderBase.AUTHORITY.....) is called. It probably makes
more sense for that static to be set as a final by using something
like ANT as you mentioned.
Content providers are instantiated and registered before any Activity.
You could also put code to set the static into Application subclass
(different for lite/pro), to make it more explicit.
Also, what about my other apps (and 3rd party apps) that want to
access the content provider? They need to use the appropriate content
provider no matter whether lite, pro or both versions are installed.
Since you can't have two providers in the system that have the same
authority URI, it probably means that some kind of client library for
other applications is needed.
ContentResolver actually throws IllegalArgumentException if it can't
match the URI to an existing content provider, you could leverage that
to gracefully fail over from pro to lite version. Using
queryContentProviders would also be appropriate here, IMHO.
I've been thinking about what I'm try to do and it's not a million
miles away from something similar to QSB, so I feel that using a
similar model to that is probably the most sensible approach.
One other thing that also needs to be considered: when the Lite
version wants to use the content provider it's probably best it does
not use the Pro version's (if the Pro version is also installed).
Therefore there needs to be slightly different logic involved when
accessing a ContentProvider within the app, as opposed to from another
app.
On 14 December 2010 16:08, Kostya Vasilyev <[email protected]
<mailto:[email protected]>> wrote:
Mark,
The way you're doing this seems waaay too complicated.
The goal is to use common code for the content provider, while
being able to switch the authority string and the class name, agreed?
If you are building with ant, there is a task that does string
replacements.
If you are using Eclipse / library project, just create a subclass
of the common content provider base class in each of the
respective application projects. Use this subclass in the
manifest, and have it pass the authority string to the base class,
where it can be stored in a static, and used by the content
provider's clients.
Library:
class CommonContentProviderBase extends ContentProvider {
public static String AUTHORITY = null;
CommonContentProviderBase (String authority) {
AUTHORITY = authority;
}
@Override
public boolean onCreate() {
gUrlMatcher.addURI(AUTHORITY, ... );
...
}
....
}
Use like this:
Uri.ParseUri("content://" + CommonContentProviderBase.AUTHORITY.....)
Lite application:
class LiteProvider extends CommonContentProviderBase {
public LiteProvider() {
super("mark.carter.data.lite");
}
}
<provider name=".LiteProvider" authorities="mark.carter.data.lite"/>
Similar for the pro version.
-- Kostya
14.12.2010 7:17, Mark Carter пишет:
An app cannot be installed if (in a provider Manifest element) it
specifies an authority that has already been specified by an
existing
app.
This can lead to problems when installing the pro version of
an app
with the lite version already installed.
How do devs deal with this?
My current approach is to always specify an authority using
the app
package name as a prefix. This guarantees uniqueness.
Furthermore, I use a meta-data element to specify that the
lite/pro
content providers are logically the same.
In the code, I use PackageManager.queryContentProviders() to
get the
authority "candidates" (sharing the same meta-data value) and then
choose the most appropriate one to use in a Uri which I can
then pass
into ContentResolver.query().
Essentially, I'm using the meta-data element to specify what I
would
like to use as an authority, but am prevented from doing so.
This is quite cumbersome, so is there a neater way?
--
Kostya Vasilyev -- WiFi Manager + pretty widget --
http://kmansoft.wordpress.com
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