APK安裝過程簡要分析
public void installPackageAsUser(String originPath, IPackageInstallObserver2 observer,
int installFlags, String installerPackageName, VerificationParams verificationParams,
String packageAbiOverride, int userId) {
mContext.enforceCallingOrSelfPermission(android.Manifest.permission.INSTALL_PACKAGES, null);
final int callingUid = Binder.getCallingUid();
enforceCrossUserPermission(callingUid, userId, true, true, "installPackageAsUser");
if (isUserRestricted(userId, UserManager.DISALLOW_INSTALL_APPS)) {
try {
if (observer != null) {
observer.onPackageInstalled("", INSTALL_FAILED_USER_RESTRICTED, null, null);
}
} catch (RemoteException re) {
}
return;
}
if ((callingUid == Process.SHELL_UID) || (callingUid == Process.ROOT_UID)) {
installFlags |= PackageManager.INSTALL_FROM_ADB;
} else {
// Caller holds INSTALL_PACKAGES permission, so we're less strict
// about installerPackageName.
installFlags &= ~PackageManager.INSTALL_FROM_ADB;
installFlags &= ~PackageManager.INSTALL_ALL_USERS;
}
UserHandle user;
if ((installFlags & PackageManager.INSTALL_ALL_USERS) != 0) {
user = UserHandle.ALL;
} else {
user = new UserHandle(userId);
}
// Only system components can circumvent runtime permissions when installing.
if ((installFlags & PackageManager.INSTALL_GRANT_RUNTIME_PERMISSIONS) != 0
&& mContext.checkCallingOrSelfPermission(Manifest.permission
.INSTALL_GRANT_RUNTIME_PERMISSIONS) == PackageManager.PERMISSION_DENIED) {
throw new SecurityException("You need the "
+ "android.permission.INSTALL_GRANT_RUNTIME_PERMISSIONS permission "
+ "to use the PackageManager.INSTALL_GRANT_RUNTIME_PERMISSIONS flag");
}
verificationParams.setInstallerUid(callingUid);
final File originFile = new File(originPath);
final OriginInfo origin = OriginInfo.fromUntrustedFile(originFile);
// 直接交給mHandler來處理了，這個mHandler在PackageManagerService構造函數中初始化，是一個PackageHandler實例
final Message msg = mHandler.obtainMessage(INIT_COPY);
msg.obj = new InstallParams(origin, null, observer, installFlags, installerPackageName,
null, verificationParams, user, packageAbiOverride, null);
mHandler.sendMessage(msg);
}
PackageHandler.handleMessage()
public void handleMessage(Message msg) {
try {
doHandleMessage(msg);
} finally {
Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
}
}
PackageHandler.doHandleMessage()
void doHandleMessage(Message msg) {
switch (msg.what) {
case INIT_COPY: {
// 從下面的邏輯中可以看到，APK的安裝是需要依賴另外一個名為
// com.android.defcontainer.DefaultContainerService服務
// params真實為InstallParams
HandlerParams params = (HandlerParams) msg.obj;
int idx = mPendingInstalls.size();
if (DEBUG_INSTALL) Slog.i(TAG, "init_copy idx=" + idx + ": " + params);
// If a bind was already initiated we dont really
// need to do anything. The pending install
// will be processed later on.
if (!mBound) {// 如果沒有綁定到com.android.defcontainer.DefaultContainerService
// If this is the only one pending we might
// have to bind to the service again.
if (!connectToService()) {// 綁定服務
Slog.e(TAG, "Failed to bind to media container service");
params.serviceError();
return;
} else {
// Once we bind to the service, the first
// pending request will be processed.
mPendingInstalls.add(idx, params);
}
} else {// 如果已經綁定了com.android.defcontainer.DefaultContainerService服務
// 添加到任務集合中
mPendingInstalls.add(idx, params);
// Already bound to the service. Just make
// sure we trigger off processing the first request.
if (idx == 0) {
mHandler.sendEmptyMessage(MCS_BOUND);
}
}
break;
}
case MCS_BOUND: {
if (DEBUG_INSTALL) Slog.i(TAG, "mcs_bound");
if (msg.obj != null) {
mContainerService = (IMediaContainerService) msg.obj;
}
if (mContainerService == null) {
if (!mBound) {// 綁定服務失敗，不能進行APK安裝
// Something seriously wrong since we are not bound and we are not
// waiting for connection. Bail out.
Slog.e(TAG, "Cannot bind to media container service");
for (HandlerParams params : mPendingInstalls) {
// Indicate service bind error
params.serviceError();
}
mPendingInstalls.clear();
} else {// 等待連接到服務
Slog.w(TAG, "Waiting to connect to media container service");
}
} else if (mPendingInstalls.size() > 0) {
// 取得第一個任務
HandlerParams params = mPendingInstalls.get(0);
if (params != null) {
if (params.startCopy()) {
// We are done... look for more work or to
// go idle.
if (DEBUG_SD_INSTALL) Log.i(TAG,
"Checking for more work or unbind...");
// Delete pending install
if (mPendingInstalls.size() > 0) {
mPendingInstalls.remove(0);
}
if (mPendingInstalls.size() == 0) {// 沒有其他APK要安裝
if (mBound) {
if (DEBUG_SD_INSTALL) Log.i(TAG,
"Posting delayed MCS_UNBIND");
removeMessages(MCS_UNBIND);
Message ubmsg = obtainMessage(MCS_UNBIND);
// Unbind after a little delay, to avoid
// continual thrashing.
sendMessageDelayed(ubmsg, 10000);
}
} else {// 還有其他APK要安裝，進入循環安裝
// There are more pending requests in queue.
// Just post MCS_BOUND message to trigger processing
// of next pending install.
if (DEBUG_SD_INSTALL) Log.i(TAG,
"Posting MCS_BOUND for next work");
mHandler.sendEmptyMessage(MCS_BOUND);
}
}
}
} else {
// Should never happen ideally.
Slog.w(TAG, "Empty queue");
}
break;
}
}
}
主要的工作就是在HandlerParams.startCopy()里面了，其職責如下：
1)確定APK是安裝在內存中還是SDCard中，安裝位置確定
2)對APK文件進行拷貝操作
在確定了安裝位置和拷貝了APK文件后，通過handleReturnCode()-->processPendingInstall()來進行安裝操作了，其實還是對APK進行解析操作。
