開篇
核心源碼
| 關鍵類 | 路徑 |
|---|---|
| Context.java | frameworks/base/core/java/android/content/Context.java |
| ContextImpl.java | frameworks/base/core/java/android/app/ContextImpl.java |
| PackageManager.java | frameworks/base/core/java/android/content/pm/PackageManager.java |
| ApplicationPackageManager.java | frameworks/base/core/java/android/app/ApplicationPackageManager.java |
| ActivityThread.java | frameworks/base/core/java/android/app/ActivityThread.java |
PackageManager
簡介
PackageManager 是一個抽象類：
/**
* Class for retrieving various kinds of information related to the application
* packages that are currently installed on the device.
*
* You can find this class through {@link Context#getPackageManager}.
*/
public abstract class PackageManager {註釋可以看出：PackageManager 這個類是檢測當前已經安裝在當前設備上的應用程序包的信息。你可以調用 Context 類的 getPackageManager() 方法來獲取 PackageManager。
安裝 APK
PackageManager 是一個實際上管理應用程序安裝、卸載和升級的 API。當我們安裝 APK 文件時，PackageManager 會解析 APK 包文件和顯示確認信息。當我們點擊 OK 按鈕後，PackageManager 會調用一個叫 "InstallPackage" 的方法，這個方法有 4 個參數，也就是 uri、installFlags、observer、installPackagename。PackageManager 會啓動一個叫 "package" 的 servcie 服務，現在所有模糊的東西會發生在這個 service 中。
實現功能
✨ 1、安裝、卸載應用
✨ 2、查詢 permission 相關信息
✨ 3、查詢 Application 相關信息(application、activity、receiver、service、provider 及相應屬性等)
✨ 4、查詢已安裝應用
✨ 5、增加、刪除 permission
✨ 6、清除用戶數據、緩存、代碼等
抽象方法
getPackageInfo
/**
* Retrieve overall information about an application package that is
* installed on the system.
*
* @param packageName The full name (i.e. com.google.apps.contacts) of the
* desired package.
* @param flags Additional option flags to modify the data returned.
* @return A PackageInfo object containing information about the package. If
* flag {@code MATCH_UNINSTALLED_PACKAGES} is set and if the package
* is not found in the list of installed applications, the package
* information is retrieved from the list of uninstalled
* applications (which includes installed applications as well as
* applications with data directory i.e. applications which had been
* deleted with {@code DONT_DELETE_DATA} flag set).
* @throws NameNotFoundException if a package with the given name cannot be
* found on the system.
*
* 通過包名獲取該包名對應的應用程序的 PackageInfo 對象，
* PackageInfo 類包含了從 AndroidManifest.xml 文件中收集的所有信息。
*/
public abstract PackageInfo getPackageInfo(String packageName, @PackageInfoFlags int flags)
throws NameNotFoundException;getApplicationInfo
/**
* Retrieve all of the information we know about a particular
* package/application.
*
* @param packageName The full name (i.e. com.google.apps.contacts) of an
* application.
* @param flags Additional option flags to modify the data returned.
* @return An {@link ApplicationInfo} containing information about the
* package. If flag {@code MATCH_UNINSTALLED_PACKAGES} is set and if
* the package is not found in the list of installed applications,
* the application information is retrieved from the list of
* uninstalled applications (which includes installed applications
* as well as applications with data directory i.e. applications
* which had been deleted with {@code DONT_DELETE_DATA} flag set).
* @throws NameNotFoundException if a package with the given name cannot be
* found on the system.
*
* 根據包名返回其對應的 ApplicationInfo 信息。
*/
public abstract ApplicationInfo getApplicationInfo(String packageName,
@ApplicationInfoFlags int flags) throws NameNotFoundException;getActivityInfo
/**
* Retrieve all of the information we know about a particular activity
* class.
*
* @param component The full component name (i.e.
* com.google.apps.contacts/com.google.apps.contacts.
* ContactsList) of an Activity class.
* @param flags Additional option flags to modify the data returned.
* @return An {@link ActivityInfo} containing information about the
* activity.
* @throws NameNotFoundException if a package with the given name cannot be
* found on the system.
*
* 檢索出一個特定的 Activity 類的所有信息。
*/
public abstract ActivityInfo getActivityInfo(ComponentName component,
@ComponentInfoFlags int flags) throws NameNotFoundException;getReceiverInfo
/**
* Retrieve all of the information we know about a particular receiver
* class.
*
* @param component The full component name (i.e.
* com.google.apps.calendar/com.google.apps.calendar.
* CalendarAlarm) of a Receiver class.
* @param flags Additional option flags to modify the data returned.
* @return An {@link ActivityInfo} containing information about the
* receiver.
* @throws NameNotFoundException if a package with the given name cannot be
* found on the system.
*
* 檢索出一個特定的 Receiver 類的所有信息(這裏主要指 ActivityInfo)。
*/
public abstract ActivityInfo getReceiverInfo(ComponentName component,
@ComponentInfoFlags int flags) throws NameNotFoundException;getServiceInfo
/**
* Retrieve all of the information we know about a particular service class.
*
* @param component The full component name (i.e.
* com.google.apps.media/com.google.apps.media.
* BackgroundPlayback) of a Service class.
* @param flags Additional option flags to modify the data returned.
* @return A {@link ServiceInfo} object containing information about the
* service.
* @throws NameNotFoundException if a package with the given name cannot be
* found on the system.
*
* 檢索出一個特定的 Service 類的所有信息(這裏主要指 ServiceInfo)。
*/
public abstract ServiceInfo getServiceInfo(ComponentName component,
@ComponentInfoFlags int flags) throws NameNotFoundException;getProviderInfo
/**
* Retrieve all of the information we know about a particular content
* provider class.
*
* @param component The full component name (i.e.
* com.google.providers.media/com.google.providers.media.
* MediaProvider) of a ContentProvider class.
* @param flags Additional option flags to modify the data returned.
* @return A {@link ProviderInfo} object containing information about the
* provider.
* @throws NameNotFoundException if a package with the given name cannot be
* found on the system.
*
* 檢索出一個特定的 content provider 類的所有信息(這裏主要指 ProviderInfo)。
*/
public abstract ProviderInfo getProviderInfo(ComponentName component,
@ComponentInfoFlags int flags) throws NameNotFoundException;getInstalledPackages
/**
* Return a List of all packages that are installed for the current user.
*
* @param flags Additional option flags to modify the data returned.
* @return A List of PackageInfo objects, one for each installed package,
* containing information about the package. In the unlikely case
* there are no installed packages, an empty list is returned. If
* flag {@code MATCH_UNINSTALLED_PACKAGES} is set, the package
* information is retrieved from the list of uninstalled
* applications (which includes installed applications as well as
* applications with data directory i.e. applications which had been
* deleted with {@code DONT_DELETE_DATA} flag set).
*
* 獲取設備上安裝的所有軟件包。
*/
public abstract List<PackageInfo> getInstalledPackages(@PackageInfoFlags int flags);currentToCanonicalPackageNames
/**
* Map from the current package names in use on the device to whatever
* the current canonical name of that package is.
* @param names Array of current names to be mapped.
* @return Returns an array of the same size as the original, containing
* the canonical name for each package.
*
* 從設備上使用當前包名映射到該軟件包名的當前規範名稱，
* 如果修改包名會用到，沒有修改過包名一般不會用到。
*/
public abstract String[] currentToCanonicalPackageNames(String[] names);canonicalToCurrentPackageNames
/**
* Map from a packages canonical name to the current name in use on the device.
* @param names Array of new names to be mapped.
* @return Returns an array of the same size as the original, containing
* the current name for each package.
*
* 將軟件包規範名稱映射到設備上正在使用的當前名稱，
* 我們發現：canonicalToCurrentPackageNames() 和 currentToCanonicalPackageNames() 方法是相反的兩個方法
*/
public abstract String[] canonicalToCurrentPackageNames(String[] names);getPermissionInfo
/**
* Retrieve all of the information we know about a particular permission.
*
* @param name The fully qualified name (i.e. com.google.permission.LOGIN)
* of the permission you are interested in.
* @param flags Additional option flags to modify the data returned.
* @return Returns a {@link PermissionInfo} containing information about the
* permission.
* @throws NameNotFoundException if a package with the given name cannot be
* found on the system.
*
* 檢測出我們想要知道的所有關於權限的信息。
*/
public abstract PermissionInfo getPermissionInfo(String name, @PermissionInfoFlags int flags)
throws NameNotFoundException;queryPermissionsByGroup
/**
* Query for all of the permissions associated with a particular group.
*
* @param group The fully qualified name (i.e. com.google.permission.LOGIN)
* of the permission group you are interested in. Use null to
* find all of the permissions not associated with a group.
* @param flags Additional option flags to modify the data returned.
* @return Returns a list of {@link PermissionInfo} containing information
* about all of the permissions in the given group.
* @throws NameNotFoundException if a package with the given name cannot be
* found on the system.
*
* 查詢與特定組相關的所有權限。
*/
public abstract List<PermissionInfo> queryPermissionsByGroup(String group,
@PermissionInfoFlags int flags) throws NameNotFoundException;getAllPermissionGroups
/**
* Retrieve all of the known permission groups in the system.
*
* @param flags Additional option flags to modify the data returned.
* @return Returns a list of {@link PermissionGroupInfo} containing
* information about all of the known permission groups.
*
* 檢索出系統中所有已知的權限。
*/
public abstract List<PermissionGroupInfo> getAllPermissionGroups(
@PermissionGroupInfoFlags int flags);當然除了上面列舉出來的方法以外，還有其他很多方法，我們不再一一列出來，如果後面分析遇到會再單獨拿出來分析！
安裝方法
接下來我們來看看 PackageManager 中關於安裝的幾個方法！
InstallPackage
/**
* packageURI：表示安裝的路徑，可以是 "file:" 或者 "content:" 的 URI
* observer： 一個回調的觀察者，有了這個觀察者，就可以在軟件包安裝完成後得到安裝結果的通知。
* 如果安裝完成會調用這個觀察者 IPackageInstallObserver 的 packageInstalled(String，int)方法，observer這個入參不能爲空。
* flags： 標誌位參數
* nstallerPackageName：正在進行安裝的安裝包包名
*/
/**
* @deprecated replaced by {@link PackageInstaller}
* @hide
*/
@Deprecated
public abstract void installPackage( // 棄用
Uri packageURI,
IPackageInstallObserver observer,
@InstallFlags int flags,
String installerPackageName);
/**
* @deprecated replaced by {@link PackageInstaller}
* @hide
*/
@Deprecated
public abstract void installPackage( // 棄用
Uri packageURI,
PackageInstallObserver observer,
@InstallFlags int flags,
String installerPackageName);從 8.1 開始，已經棄用了 installPackage 方法（9.0 的代碼中已經去除 installPackage 代碼了），而是使用 PackageInstaller 執行應用的安裝、升級和刪除操作。
/**
* Return interface that offers the ability to install, upgrade, and remove
* applications on the device.
*/
public abstract @NonNull PackageInstaller getPackageInstaller();installExistingPackage
/**
* If there is already an application with the given package name installed
* on the system for other users, also install it for the calling user.
* @hide
*/
@SystemApi // 系統 API
public abstract int installExistingPackage(String packageName) throws NameNotFoundException;通過註釋可以看出這個方法的用途：如果系統上已經安裝相同包名的應用程序，則重複重新安裝。
具體實現類
我們知道 PackageManager 是一個抽象類，它裏面很重要的方法都是抽象的，所以在具體執行的時候，肯定是它的實現子類，那麼我們就來看下它的具體實現類。
前面我們講解 PackageManager 類的時候，官網推薦獲取 PackageManager 對象的方法是 Context 的 Context#getPackageManager() 方法，那我們來看下：
// frameworks/base/core/java/android/content/Context.java
/** Return PackageManager instance to find global package information. */
public abstract PackageManager getPackageManager();我們知道 Context 也是一個抽象類，而它的 getPackageManager() 也是抽象方法，但 Context 的具體實現類是 ContextImpl，那我們就去 ContextImpl 裏面看下：
/**
* Common implementation of Context API, which provides the base
* context object for Activity and other application components.
* @hide
*/
public class ContextImpl extends Context {
private PackageManager mPackageManager;
... ...
@Override
public PackageManager getPackageManager() {
// 判斷 mPackageManager 是否爲空，如果爲空，則說明是第一次調用
if (mPackageManager != null) {
return mPackageManager;
}
// 調用 ActivityThread 的靜態方法 getPackageManager() 獲取一個 IPackageManager 對象
IPackageManager pm = ActivityThread.getPackageManager();
// 如果獲取的 IPackageManager 對象不爲空，則構造一個 ApplicationPackageManager 對象，ApplicationPackageManager 是 PackageManager 的子類
if (pm != null) {
// Doesn't matter if we make more than one instance.
return (mPackageManager = new ApplicationPackageManager(this, pm));
}
return null;
}
... ...
}所以，在我們平時調用 Context 的 getPackageManager()方法後，其實返回的是 ApplicationPackageManager 這個類。
ApplicationPackageManager
簡介
我們先來看下 ApplicationPackageManager 類的源碼：
/** @hide */
public class ApplicationPackageManager extends PackageManager {通過源碼我們知道 ApplicationPackageManager 繼承自PackageManager，而且 ApplicationPackageManager 類不是抽象的，所以 ApplicationPackageManager 必然實現了 PackageManager 的所有抽象方法。
構造函數
protected ApplicationPackageManager(ContextImpl context, IPackageManager pm) {
mContext = context;
mPM = pm;
}InstallPackage
在講解 PackageManager 的時候，我們提到過安裝 APK 會調用 InstallPackage 方法（Android 8.1，9.0 已棄用），我們看下在 ApplicationPackageManager 中的具體實現：
@Override
public void installPackage(Uri packageURI, IPackageInstallObserver observer, int flags,
String installerPackageName) {
installCommon(packageURI, new LegacyPackageInstallObserver(observer), flags,
installerPackageName, mContext.getUserId());
}installCommon
// 源碼來自：Android 8.1，9.0 已棄用
private void installCommon(Uri packageURI,
PackageInstallObserver observer, int flags, String installerPackageName,
int userId) {
// scheme 判斷，如果非 "file" 則拋異常，因爲只支持 file 格式的 URI
if (!"file".equals(packageURI.getScheme())) {
throw new UnsupportedOperationException("Only file:// URIs are supported");
}
// 獲取相應的路徑
final String originPath = packageURI.getPath();
try {
// 調用 installPackageAsUser 方法
mPM.installPackageAsUser(originPath, observer.getBinder(), flags, installerPackageName, userId);
} catch (RemoteException e) {
throw e.rethrowFromSystemServer();
}
}可以發現，public abstract void installPackage() 方法其內部本質是調用的 IPackageManager 的 installPackageAsUser() 方法。
IPackageManager
ActivityThread
我們先來看看如下代碼（上面沒有分析）：
// 調用 ActivityThread 的靜態方法 getPackageManager() 獲取一個 IPackageManager 對象
IPackageManager pm = ActivityThread.getPackageManager();跟蹤 getPackageManager()：
static volatile IPackageManager sPackageManager;
public static IPackageManager getPackageManager() {
// 判斷 sPackageManager 是否爲空，如果爲空，則說明是的第一次調用，走第二步，如果不爲空，則直接返回 sPackageManager
if (sPackageManager != null) {
return sPackageManager;
}
// 能走到第二步，說明這是第一次調用，則調用 ServiceManager 的 getService(String) 方法獲取一個 IBinder 對象
IBinder b = ServiceManager.getService("package");
// 調用 IPackageManager.Stub.asInterface(IBinder) 獲取一個 sPackageManager 對象
sPackageManager = IPackageManager.Stub.asInterface(b);
return sPackageManager;
}IPM/PM/PMS 三者關聯
APM/PMS/IPM
在上面分析 ContextImpl 的 getPackageManager() 方法裏面，我們知道：
IPackageManager pm = ActivityThread.getPackageManager();
if (pm != null) {
// Doesn't matter if we make more than one instance.
return (mPackageManager = new ApplicationPackageManager(this, pm));
}而在 ActivityThread 的靜態方法 getPackageManager() 裏面：
sPackageManager = IPackageManager.Stub.asInterface(b);
return sPackageManager;所以在 ApplicationPackageManager 裏面的 mPM 其實就是 IPackageManager.Stub 內部類 Proxy 對象。
那對應的 IPackageManager.Stub 是什麼？其實就是 PackageManagerService.java 。
public class PackageManagerService extends IPackageManager.Stub implements PackageSender {如下圖所示：
小結
結合上面的知識，再結合 PackageManager、ApplicationPackageManager 和 PackageManagerService 總結如下：
✨ IPackageManager 負責通信：IPackageManager 接口類中定義了很多業務方法，但是由於安全等方面的考慮，Android 對外(即SDK)提供的僅僅是一個子集，該子集被封裝在抽象類 PackageManager 中。客戶端一般通過 Context 的 getPackageManager 函數返回一個類型爲 PackageManager 的對象，該對象的實際類型是 PackageManager 的子類 ApplicationPackageManager 。ApplicationPackageManager 並沒有直接參與 Binder 通信，而是通過 mPM 成員變量指向了一個 IPackageManager.Stub.Proxy 類型的對象。
✨ AIDL中 的 Binder 服務端是 PackageManagerService，因爲 PackageManagerService 繼承自 IPackageManager.Stub 。由於 IPackageManager.Stub 類從 Binder 派生，所以 PackageManagerService 將作爲服務端參與 Binder 通信。
✨ AIDL中 的 Binder 客戶端是 ApplicationPackageManager 中成員變量 mPM，因爲mPM內部指向的是 IPackageManager.Stub.Proxy。
整體流程的 Binder 結構大致如下：
參考
01. https://www.jianshu.com/p/c56...
02. https://www.jianshu.com/p/a30...