文章出处：http://blog.csdn.net/shift_wwx
接着之前两篇
ActivityManagerService （一）
ActivityManagerService （二）
接着总结：
ActivityManagerService.installSystemProviders()
public static final void installSystemProviders() {
List<ProviderInfo> providers;
synchronized (mSelf) {
ProcessRecord app = mSelf.mProcessNames.get("system", Process.SYSTEM_UID);
providers = mSelf.generateApplicationProvidersLocked(app);
if (providers != null) {
for (int i=providers.size()-1; i>=0; i--) {
ProviderInfo pi = (ProviderInfo)providers.get(i);
if ((pi.applicationInfo.flags&ApplicationInfo.FLAG_SYSTEM) == 0) {
Slog.w(TAG, "Not installing system proc provider " + pi.name
+ ": not system .apk");
providers.remove(i);
}
}
}
}
if (providers != null) {
mSystemThread.installSystemProviders(providers);
}
mSelf.mCoreSettingsObserver = new CoreSettingsObserver(mSelf);
mSelf.mUsageStatsService.monitorPackages();
}
从函数表面是看，获取system进程的providers，然后过滤出system的providers进行install。
1）这里的app是在之前ActivityManagerService （二）setSystemProcess中提到过的：
mSelf.mProcessNames.put(app.processName, app.uid, app);显然app.processName就是system，app.uid指的也是system_uid。
2）通过函数generateApplicationProvidersLocked获取providers
private final List<ProviderInfo> generateApplicationProvidersLocked(ProcessRecord app) {
List<ProviderInfo> providers = null;
try {
providers = AppGlobals.getPackageManager().
queryContentProviders(app.processName, app.uid,
STOCK_PM_FLAGS | PackageManager.GET_URI_PERMISSION_PATTERNS);
} catch (RemoteException ex) {
}
if (DEBUG_MU)
Slog.v(TAG_MU, "generateApplicationProvidersLocked, app.info.uid = " + app.uid);
int userId = app.userId;
if (providers != null) {
int N = providers.size();
app.pubProviders.ensureCapacity(N + app.pubProviders.size());
for (int i=0; i<N; i++) {
ProviderInfo cpi =
(ProviderInfo)providers.get(i);
boolean singleton = isSingleton(cpi.processName, cpi.applicationInfo,
cpi.name, cpi.flags);
if (singleton && UserHandle.getUserId(app.uid) != 0) {
// This is a singleton provider, but a user besides the
// default user is asking to initialize a process it runs
// in... well, no, it doesn't actually run in this process,
// it runs in the process of the default user. Get rid of it.
providers.remove(i);
N--;
i--;
continue;
}
ComponentName comp = new ComponentName(cpi.packageName, cpi.name);
ContentProviderRecord cpr = mProviderMap.getProviderByClass(comp, userId);
if (cpr == null) {
cpr = new ContentProviderRecord(this, cpi, app.info, comp, singleton);
mProviderMap.putProviderByClass(comp, cpr);
}
if (DEBUG_MU)
Slog.v(TAG_MU, "generateApplicationProvidersLocked, cpi.uid = " + cpr.uid);
app.pubProviders.put(cpi.name, cpr);
if (!cpi.multiprocess || !"android".equals(cpi.packageName)) {
// Don't add this if it is a platform component that is marked
// to run in multiple processes, because this is actually
// part of the framework so doesn't make sense to track as a
// separate apk in the process.
app.addPackage(cpi.applicationInfo.packageName, mProcessStats);
}
ensurePackageDexOpt(cpi.applicationInfo.packageName);
}
}
return providers;
}（1）AppGlobals.getPackageManager()
public static IPackageManager getPackageManager() {
return ActivityThread.getPackageManager();
}接着： public static IPackageManager getPackageManager() {
if (sPackageManager != null) {
//Slog.v("PackageManager", "returning cur default = " + sPackageManager);
return sPackageManager;
}
IBinder b = ServiceManager.getService("package");
//Slog.v("PackageManager", "default service binder = " + b);
sPackageManager = IPackageManager.Stub.asInterface(b);
//Slog.v("PackageManager", "default service = " + sPackageManager);
return sPackageManager;
}似曾相识过吧，在ActivityManagerService （二）setSystemProcess中提到过：
ApplicationInfo info =mSelf.mContext.getPackageManager().getApplicationInfo("android", STOCK_PM_FLAGS);不过这里是通过context获取PMS：
@Override
public PackageManager getPackageManager() {
if (mPackageManager != null) {
return mPackageManager;
}
IPackageManager pm = ActivityThread.getPackageManager();
if (pm != null) {
// Doesn't matter if we make more than one instance.
return (mPackageManager = new ApplicationPackageManager(this, pm));
}
return null;
}不过最终还是会调用到ActivityThread.getPackageManager();我想这里没有用AMS中mSystemThread应该是为了区分system和非system的app吧。static IPackageManager sPackageManager;所以用的是一个PMS。
（2）queryContentProviders
public List<ProviderInfo> queryContentProviders(String processName,
int uid, int flags) {
ArrayList<ProviderInfo> finalList = null;
// reader
synchronized (mPackages) {
final Iterator<PackageParser.Provider> i = mProviders.mProviders.values().iterator();
final int userId = processName != null ?
UserHandle.getUserId(uid) : UserHandle.getCallingUserId();
while (i.hasNext()) {
final PackageParser.Provider p = i.next();
PackageSetting ps = mSettings.mPackages.get(p.owner.packageName);
if (ps != null && p.info.authority != null
&& (processName == null
|| (p.info.processName.equals(processName)
&& UserHandle.isSameApp(p.info.applicationInfo.uid, uid)))
&& mSettings.isEnabledLPr(p.info, flags, userId)
&& (!mSafeMode
|| (p.info.applicationInfo.flags & ApplicationInfo.FLAG_SYSTEM) != 0)) {
if (finalList == null) {
finalList = new ArrayList<ProviderInfo>(3);
}
ProviderInfo info = PackageParser.generateProviderInfo(p, flags,
ps.readUserState(userId), userId);
if (info != null) {
finalList.add(info);
}
}
}
}
if (finalList != null) {
Collections.sort(finalList, mProviderInitOrderSorter);
}
return finalList;
}这个函数中：
final Iterator<PackageParser.Provider> i = mProviders.mProviders.values().iterator();
不知道怎么来的，需要跟一下PMS.main，对于PMS详细过程，后期会总结，这里应该是通过PMS解析后搜集了所有的providers。
过滤条件比较多，authority不能为null，processName是system，uid是system_uid，flags的第0 bit位是FLAG_SYSTEM。
（3）app.pubProviders.ensureCapacity(N + app.pubProviders.size());
更新pubProviders的size。
final ArrayMap<String, ContentProviderRecord> pubProviders = new ArrayMap<String, ContentProviderRecord>();（4）处理provider
mProviderMap.putProviderByClass(comp, cpr);//加到AMS中的ProviderMap中
final ProviderMap mProviderMap;//mProviderMap是final的
app.pubProviders.put(cpi.name, cpr);//加到ProcessRecord里面的pubProviders
final ArrayMap<String, ContentProviderRecord> pubProviders
= new ArrayMap<String, ContentProviderRecord>();
app.addPackage(cpi.applicationInfo.packageName, mProcessStats);//将package加到ProcessRecord中的pkgList
public boolean addPackage(String pkg, ProcessStatsService tracker) {
if (!pkgList.containsKey(pkg)) {
if (baseProcessTracker != null) {//baseProcessTracker在之前的AMS.setSystemProcess中的makeActive中初始化过
ProcessStats.ProcessState state = tracker.getProcessStateLocked(
pkg, info.uid, processName);
pkgList.put(pkg, state);
if (state != baseProcessTracker) {
state.makeActive();
}
} else {
pkgList.put(pkg, null);
}
return true;
}
return false;
}
结合之前的AMS.setSystemProcess，这时ProcessRecord就有两个package在里面了，一个是framework-res.apk中所指的android package，另一个就是这里的process name 是system，uid是system_uid的provider。
看一下AMS和ProcessRecord中保存SettingsProvider的数据结构。
弄了半天，这样的provider在andorid系统有中有哪些呢？为什么要在AMS初始化的前期一定要初始化提出来这些provider，经过检查发现了这样的provider：
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.android.providers.settings"
coreApp="true"
android:sharedUserId="android.uid.system">
<application android:allowClearUserData="false"
android:label="@string/app_label"
android:process="system"
android:backupAgent="SettingsBackupAgent"
android:killAfterRestore="false"
android:icon="@mipmap/ic_launcher_settings">
<!-- todo add: android:neverEncrypt="true" -->
<provider android:name="SettingsProvider" android:authorities="settings"
android:multiprocess="false"
android:exported="true"
android:writePermission="android.permission.WRITE_SETTINGS"
android:initOrder="100" />
</application>
</manifest>
看到package name就知道了，是SettingsProvider.apk。至于SettingsProvider具体作用这里不做解释，一些系统的默认参数都是通过这里设置，通过db来实现进程间数据共享等等。
3）mSystemThread.installSystemProviders(providers);
if (providers != null) {
mSystemThread.installSystemProviders(providers);
} public final void installSystemProviders(List<ProviderInfo> providers) {
if (providers != null) {
installContentProviders(mInitialApplication, providers);
}
} public final void installSystemProviders(List<ProviderInfo> providers) {
if (providers != null) {
installContentProviders(mInitialApplication, providers);
}
} private void installContentProviders(
Context context, List<ProviderInfo> providers) {
final ArrayList<IActivityManager.ContentProviderHolder> results =
new ArrayList<IActivityManager.ContentProviderHolder>();
for (ProviderInfo cpi : providers) {
if (DEBUG_PROVIDER) {
StringBuilder buf = new StringBuilder(128);
buf.append("Pub ");
buf.append(cpi.authority);
buf.append(": ");
buf.append(cpi.name);
Log.i(TAG, buf.toString());
}
IActivityManager.ContentProviderHolder cph = installProvider(context, null, cpi,
false /*noisy*/, true /*noReleaseNeeded*/, true /*stable*/);
if (cph != null) {
cph.noReleaseNeeded = true;
results.add(cph);
}
}
try {
ActivityManagerNative.getDefault().publishContentProviders(
getApplicationThread(), results);
} catch (RemoteException ex) {
}
}context是上面传进来的mInitialApplication，其实就是mSystemContext。先不管ContextProviderHolder是什么，来看看获取这个cph的地方，installProvider：
private IActivityManager.ContentProviderHolder installProvider(Context context,
IActivityManager.ContentProviderHolder holder, ProviderInfo info,
boolean noisy, boolean noReleaseNeeded, boolean stable) {
ContentProvider localProvider = null;
IContentProvider provider;
if (holder == null || holder.provider == null) {
if (DEBUG_PROVIDER || noisy) {
Slog.d(TAG, "Loading provider " + info.authority + ": "
+ info.name);
}
Context c = null;
ApplicationInfo ai = info.applicationInfo;
if (context.getPackageName().equals(ai.packageName)) {
c = context;
} else if (mInitialApplication != null &&
mInitialApplication.getPackageName().equals(ai.packageName)) {
c = mInitialApplication;
} else {
try {
c = context.createPackageContext(ai.packageName,
Context.CONTEXT_INCLUDE_CODE);
} catch (PackageManager.NameNotFoundException e) {
// Ignore
}
}
if (c == null) {
Slog.w(TAG, "Unable to get context for package " +
ai.packageName +
" while loading content provider " +
info.name);
return null;
}
try {
final java.lang.ClassLoader cl = c.getClassLoader();
localProvider = (ContentProvider)cl.
loadClass(info.name).newInstance();
provider = localProvider.getIContentProvider();
if (provider == null) {
Slog.e(TAG, "Failed to instantiate class " +
info.name + " from sourceDir " +
info.applicationInfo.sourceDir);
return null;
}
if (DEBUG_PROVIDER) Slog.v(
TAG, "Instantiating local provider " + info.name);
// XXX Need to create the correct context for this provider.
localProvider.attachInfo(c, info);
} catch (java.lang.Exception e) {
if (!mInstrumentation.onException(null, e)) {
throw new RuntimeException(
"Unable to get provider " + info.name
+ ": " + e.toString(), e);
}
return null;
}
} else {
provider = holder.provider;
if (DEBUG_PROVIDER) Slog.v(TAG, "Installing external provider " + info.authority + ": "
+ info.name);
}
IActivityManager.ContentProviderHolder retHolder;
synchronized (mProviderMap) {
if (DEBUG_PROVIDER) Slog.v(TAG, "Checking to add " + provider
+ " / " + info.name);
IBinder jBinder = provider.asBinder();
if (localProvider != null) {
ComponentName cname = new ComponentName(info.packageName, info.name);
ProviderClientRecord pr = mLocalProvidersByName.get(cname);
if (pr != null) {
if (DEBUG_PROVIDER) {
Slog.v(TAG, "installProvider: lost the race, "
+ "using existing local provider");
}
provider = pr.mProvider;
} else {
holder = new IActivityManager.ContentProviderHolder(info);
holder.provider = provider;
holder.noReleaseNeeded = true;
pr = installProviderAuthoritiesLocked(provider, localProvider, holder);
mLocalProviders.put(jBinder, pr);
mLocalProvidersByName.put(cname, pr);
}
retHolder = pr.mHolder;
} else {
ProviderRefCount prc = mProviderRefCountMap.get(jBinder);
if (prc != null) {
if (DEBUG_PROVIDER) {
Slog.v(TAG, "installProvider: lost the race, updating ref count");
}
// We need to transfer our new reference to the existing
// ref count, releasing the old one... but only if
// release is needed (that is, it is not running in the
// system process).
if (!noReleaseNeeded) {
incProviderRefLocked(prc, stable);
try {
ActivityManagerNative.getDefault().removeContentProvider(
holder.connection, stable);
} catch (RemoteException e) {
//do nothing content provider object is dead any way
}
}
} else {
ProviderClientRecord client = installProviderAuthoritiesLocked(
provider, localProvider, holder);
if (noReleaseNeeded) {
prc = new ProviderRefCount(holder, client, 1000, 1000);
} else {
prc = stable
? new ProviderRefCount(holder, client, 1, 0)
: new ProviderRefCount(holder, client, 0, 1);
}
mProviderRefCountMap.put(jBinder, prc);
}
retHolder = prc.holder;
}
}
return retHolder;
}（1）传进来的holder是null，所以，直接进入if条件语句块。
然后试图确认packageName是否和mSystemContext的packageName一样，显然不一样，一个是com.android.providers.settings，一个android。
所以，索性创建了provider自己的context：
try {
c = context.createPackageContext(ai.packageName,
Context.CONTEXT_INCLUDE_CODE);
} catch (PackageManager.NameNotFoundException e) {
// Ignore
}这个函数不去详细说明，主要就是通过packageName构造一个LoadedApk，通过context init来创建一个context返回。（2）provider = localProvider.getIContentProvider();//localProvider完全可以看成是SettingsProvider
public IContentProvider getIContentProvider() {
return mTransport;
}private Transport mTransport = new Transport();
class Transport extends ContentProviderNative {
......
}abstract public class ContentProviderNative extends Binder implements IContentProvider {
......
}
集合provider定义的地方：
IContentProvider provider;
provider是个Binder，后面继续说明。
（3）localProvider.attachInfo(c, info);
public void attachInfo(Context context, ProviderInfo info) {
attachInfo(context, info, false);
}
private void attachInfo(Context context, ProviderInfo info, boolean testing) {
/*
* We may be using AsyncTask from binder threads. Make it init here
* so its static handler is on the main thread.
*/
AsyncTask.init();
mNoPerms = testing;
/*
* Only allow it to be set once, so after the content service gives
* this to us clients can't change it.
*/
if (mContext == null) {
mContext = context;
if (context != null) {
mTransport.mAppOpsManager = (AppOpsManager) context.getSystemService(
Context.APP_OPS_SERVICE);
}
mMyUid = Process.myUid();
if (info != null) {
setReadPermission(info.readPermission);
setWritePermission(info.writePermission);
setPathPermissions(info.pathPermissions);
mExported = info.exported;
}
ContentProvider.this.onCreate();
}
}创建AppOpsManager，设置SettingProvider的mMyUid，设置读写权限，设置path权限，设置mExported，最后回调SettingsProvider的onCreate函数。原来SettingsProvider在这里就创建ok了。
（4）IActivityManager.ContentProviderHolder retHolder;
可以说之前的都是初始化准备工作，这里才第一次创建ContentProviderHolder 对象。当然，局部的对象，是不可能直接返回的。
（5）ProviderClientRecord pr = mLocalProvidersByName.get(cname);
之前分析过了，在generateApplicationProvidersLocked中解析Provider的时候，只是在AMS和ProcessRecord里面有保存，ActivityThread里面是没有保存的，所以这里pr是null。
所以，会实例一个ContentProviderHolder。最后installProvider方法调用installProviderAuthoritiesLocked方法构造一个ProviderClientRecord对象，并添加到mProviderMap、mLocalProviders和mLocalProvidersByName中，这三个ArraryMap可以通过不同键值快速找到对象的ProviderClientRecord对象。最后返回ContentProviderHolder。AcitivytThread中保存SettingsProvider的信息如下：
返回installContentProviders，既然ContentProviderHolder已经ok了，接着看下一步：
ActivityManagerNative.getDefault().publishContentProviders(
getApplicationThread(), results); public final void publishContentProviders(IApplicationThread caller,
List<ContentProviderHolder> providers) {
if (providers == null) {
return;
}
enforceNotIsolatedCaller("publishContentProviders");
synchronized (this) {
final ProcessRecord r = getRecordForAppLocked(caller);
if (DEBUG_MU)
Slog.v(TAG_MU, "ProcessRecord uid = " + r.uid);
if (r == null) {
throw new SecurityException(
"Unable to find app for caller " + caller
+ " (pid=" + Binder.getCallingPid()
+ ") when publishing content providers");
}
final long origId = Binder.clearCallingIdentity();
final int N = providers.size();
for (int i=0; i<N; i++) {
ContentProviderHolder src = providers.get(i);
if (src == null || src.info == null || src.provider == null) {
continue;
}
ContentProviderRecord dst = r.pubProviders.get(src.info.name);
if (DEBUG_MU)
Slog.v(TAG_MU, "ContentProviderRecord uid = " + dst.uid);
if (dst != null) {
ComponentName comp = new ComponentName(dst.info.packageName, dst.info.name);
mProviderMap.putProviderByClass(comp, dst);
String names[] = dst.info.authority.split(";");
for (int j = 0; j < names.length; j++) {
mProviderMap.putProviderByName(names[j], dst);
}
int NL = mLaunchingProviders.size();
int j;
for (j=0; j<NL; j++) {
if (mLaunchingProviders.get(j) == dst) {
mLaunchingProviders.remove(j);
j--;
NL--;
}
}
synchronized (dst) {
dst.provider = src.provider;
dst.proc = r;
dst.notifyAll();
}
updateOomAdjLocked(r);
}
}
Binder.restoreCallingIdentity(origId);
}
}
（1）第一个参数getApplicationThread()
final ApplicationThread mAppThread = new ApplicationThread();在构造mSystemThread的时候构造的，具体的在 ActivityManagerService （二）中提到过。
（2）第二个参数就是之前创造的ContentProviderHolder
getRecordForAppLocked从mLruProcesses链表中查找并返回我们前面创建的ProcessRecord对象，我们知道在generateApplicationProvidersLocked方法中，我们将从PMS
得到的SettingsProvider信息已经添加到ProcessRecord的pubProviders数组中了，这里将provider信息添加到mProviderMap中，并从mLaunchingProviders（表示待启动的
provider列表）中移除已经启动的provider。
最后回到installSystemProviders方法中，注册一个ContentObserver来监听Settings.Secure.LONG_PRESS_TIMEOUT的变化并调用UsageStatsService去监听package的使用状态。
到这里AMS的installSystemProviders就总结完了。后期会进一步的完善。