前面,我们已经分析了，PMS我们已经分析了，PackageManagerService整个的启动过程，对android应用管理大概有一个大概的了解，实际开发中可以有一个更深入的理解，前面讲的只是一个管理大概的流程，以及数据如何存储，存储大部分都是用hashmap来存储的，这样存储也是为了查找方便，不过唯一不好的就是浪费空间。所以android的速度提升了，不过rom运行大小也增大了。
费话少说了，我们还是继续分析应用的安装过程。一般应用安装，我们都是获取PackageManager 然后调用installPackage方法，不过PackageManager真正的实现类是ApplicationPackageManager,我们看一下具体的实现：
public void installPackage(Uri packageURI, IPackageInstallObserver observer, int flags,
String installerPackageName) {
try {
mPM.installPackage(packageURI, observer, flags, installerPackageName);
} catch (RemoteException e) {
// Should never happen!
}
}这里也只是调用PMS去实现安装，所以要分析安装的过程，我们也还是要分析PMS里面的installPackage方法。不过经过各种跳转，最终还是会走到installPackageWithVerificationAndEncryption方法里面去，主要是生成一个InstallParams对象发送一个copy的消息。
final Message msg = mHandler.obtainMessage(INIT_COPY);
msg.obj = new InstallParams(packageURI, observer, filteredFlags, installerPackageName,
verificationParams, encryptionParams, user);
mHandler.sendMessage(msg);InstallParams是继承HandlerParams对象，主要是实现apk复现等其他功能。看Handler关于INIT_COPY的处理：
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) {
// If this is the only one pending we might
// have to bind to the service again.
if (!connectToService()) {
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 {
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;
}1.如果没有已经绑定过DefaultContainerService 直接添加到mPendingInstalls队列里面去 再发一个 MCS_BOUND 消息。
2.没有绑定service，则要进行绑定再添加到mPendingInstalls 队列里面。
再看一下：
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) {
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 {
// 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 woek");
mHandler.sendEmptyMessage(MCS_BOUND);
}取出mPendingInstalls里面的HandlerParams 同时调用params.startCopy()进行复制，主要是有一个重试的机制在里面。总共有4次失败的机会。真正执行复现的方法是handleStartCopy 先执行一个权限等相关的检测，最后调用DeviceStorageMonitorService 方法进行暂时文件复制：
if (mTempPackage != null) {
ParcelFileDescriptor out;
try {
out = ParcelFileDescriptor.open(mTempPackage,
ParcelFileDescriptor.MODE_READ_WRITE);
} catch (FileNotFoundException e) {
out = null;
Slog.e(TAG, "Failed to create temporary file for : " + mPackageURI);
}
// Make a temporary file for decryption.
ret = mContainerService
.copyResource(mPackageURI, encryptionParams, out);
IoUtils.closeQuietly(out);
packageFile = mTempPackage;
FileUtils.setPermissions(packageFile.getAbsolutePath(),
FileUtils.S_IRUSR | FileUtils.S_IWUSR | FileUtils.S_IRGRP
| FileUtils.S_IROTH,
-1, -1);
} else {
packageFile = null;
}
} else {
packageFile = new File(mPackageURI.getPath());
}
复制完成之后还是设置权限。不要忘记后面还是有一个
handleReturnCode方法。再看往下看：
if (packageFile != null) {
// Remote call to find out default install location
final String packageFilePath = packageFile.getAbsolutePath();
pkgLite = mContainerService.getMinimalPackageInfo(packageFilePath, flags,
lowThreshold);
/*
* If we have too little free space, try to free cache
* before giving up.
*/
if (pkgLite.recommendedInstallLocation
== PackageHelper.RECOMMEND_FAILED_INSUFFICIENT_STORAGE) {
final long size = mContainerService.calculateInstalledSize(
packageFilePath, isForwardLocked());
if (mInstaller.freeCache(size + lowThreshold) >= 0) {
pkgLite = mContainerService.getMinimalPackageInfo(packageFilePath,
flags, lowThreshold);
}
/*
* The cache free must have deleted the file we
* downloaded to install.
*
* TODO: fix the "freeCache" call to not delete
* the file we care about.
*/
if (pkgLite.recommendedInstallLocation
== PackageHelper.RECOMMEND_FAILED_INVALID_URI) {
pkgLite.recommendedInstallLocation
= PackageHelper.RECOMMEND_FAILED_INSUFFICIENT_STORAGE;
}
}
}
} finally {
mContext.revokeUriPermission(mPackageURI,
Intent.FLAG_GRANT_READ_URI_PERMISSION);
}
}暂时文件复制成功之后会调用getMinimalPackageInfo 扫描获取包的信息：
public PackageInfoLite getMinimalPackageInfo(final String packagePath, int flags,
long threshold) {
PackageInfoLite ret = new PackageInfoLite();
if (packagePath == null) {
Slog.i(TAG, "Invalid package file " + packagePath);
ret.recommendedInstallLocation = PackageHelper.RECOMMEND_FAILED_INVALID_APK;
return ret;
}
DisplayMetrics metrics = new DisplayMetrics();
metrics.setToDefaults();
PackageParser.PackageLite pkg = PackageParser.parsePackageLite(packagePath, 0);
if (pkg == null) {
Slog.w(TAG, "Failed to parse package");
final File apkFile = new File(packagePath);
if (!apkFile.exists()) {
ret.recommendedInstallLocation = PackageHelper.RECOMMEND_FAILED_INVALID_URI;
} else {
ret.recommendedInstallLocation = PackageHelper.RECOMMEND_FAILED_INVALID_APK;
}
return ret;
}
ret.packageName = pkg.packageName;
ret.versionCode = pkg.versionCode;
ret.installLocation = pkg.installLocation;
ret.verifiers = pkg.verifiers;
ret.recommendedInstallLocation = recommendAppInstallLocation(pkg.installLocation,
packagePath, flags, threshold);
return ret;
}parsePackageLite解析包的信息，这个方法很重要，不过前面已经讲过了，这里就不再分析，解析包之后就可以拿到包的主要信息，还有另外一个方法比较重要：
recommendAppInstallLocation 读取设置里面的信息和apk 本身设置的安装路径，根据剩下空间等因素，确定最终路径.
接下来创建InstallArgs ,createInstallArgs方法会根据不同的安装路径选择生成对象.再调用copyApk方法复制 apk包，lib库等。
最后，再看一下handleReturnCode方法：主要是做扫尾工作，删除临时文件，不过最重要的还是processPendingInstall方法：
第一.扫描apk，解析然后把数据充分(把应用的相关信息添加到 Settings里面);
第二.发送POST_INSTALL删除安装过程中生成的临时文件。
