Summary of info classes

First, let's take a look. Packageiteminfo, It is a base class that contains some information. Its direct subclasses include: Applicationinfo , Componentinfo , Instrumentationinfo , Permissiongroupinfo , Permissioninfo . Its indirect subclasses include: Activityinfo ,Providerinfo , Serviceinfo . The information contained in this class is equal for all projects in the package. These Package items Yes Package Manager . This class provides basic settings for attributes: Label , Icon And Meta-daTa . This class is not intended to be called by itself. It is simply shared herePackage Manager All Items . For example, it is not implemented by itself Parcelable Interface, but it helps to implement Parcelable Subclass provides a convenient method.

ApplicationinfoIs the information obtained from a specific application. The information is relativeAndrodimanifest. xmlOf<Application>Tag.

ResolveinfoThis class resolvesIntentfilterCorrespondingIntentThe obtained information. It partially corresponds toAndroidmanifest. xmlOf<Intent>Tag Information.

PackagemanagerThis class is used to return information about various packages associated with the applications currently mounted to the device. You can useGetpacagemanagerTo obtain this class.

ApplicationinfoAndResolveinfoComparison: the former can obtainIcon,Label,Meta-daTa,Description. The latter can only getIcon,Label.

The following describes the specific applications that combine these categories:

By callingPackagemanagerYou can get two different types of information:

First, you must obtainManager:

 
1 Packagemanager Manager=Getpackagemanager ();
 

Method 1:

List <applicationinfo> applist = manager. getinstalledapplications (packagemanager. Get. uninstalled_pakages );

It is resolved throughAndroidmanifest. xmlOf<Application>Label, so it can get allApp.

Method 2:

 1   Intent intent  =     New  Intent (intent. A ction_main,  Null  );
 2   
  3   Intent. addcategory (intent. category_launcher );
  4   
  5   List  <  Resolveinfo  >  Applist  =  Manager. queryintentactivities (intent,  0  ); 

It is resolved through<Intent-filter>The tag is

1 <Action Android: Name="Android. Intent. Action. Main"/>
2 
3 <Action Android: Name="Android. Intent. Category. launcher"/>
 

app, , so we get less than the first method (the former is more than the service , previder and other app ).