安装app时packagemanager 读取manixfest获取provider信息 存在数据库里
流程：
1、加载ActivityThread main方法，创建消息队列。ActivityThread.main:
Looper.prepareMainLooper();
ActivityThread thread = new ActivityThread();
thread.attach(false); （2）
sMainThreadHandler = thread.getHandler();
Looper.loop();
2、ActivityThread.attach:
final IActivityManager mgr = ActivityManagerNative.getDefault();
mgr.attachApplication(mAppThread); //IPC把ApplicationThread 传递给AMS (3)
mInstrumentation = new Instrumentation();
ContextImpl context = ContextImpl.createAppContext(this, getSystemContext().mPackageInfo);
mInitialApplication = context.mPackageInfo.makeApplication(true, null);
3、ActivityManagerService.attachApplication => ActivityManagerService.attachApplicationLocked:
List<ProviderInfo> providers = normalMode ? generateApplicationProvidersLocked(app) //获取packageManager中这个包注册的provider信息
thread.bindApplication(processName, appInfo, providers, ...) //IPC调用app端的bindApplication
4. ActivityThread.bindApplication => ActivityThread.handleBindApplication
List<ProviderInfo> providers = data.providers;
installContentProviders(app, providers); (5)
mInstrumentation.callApplicationOnCreate(app); // call Application.onCreate()
5. ActivityThread.installContentProviders:
IActivityManager.ContentProviderHolder cph = installProvider(context, null, cpi, false, true, true); //实例化provider类
results.add(cph);
ActivityManagerNative.getDefault().publishContentProviders(getApplicationThread(), results); //发布到AMS
6. ActivityManagerService.publishContentProviders: //把ContentProviderRecord存储起来，放到mProviderMap中去
ContentProviderRecord dst = r.pubProviders.get(src.info.name);
ComponentName comp = new ComponentName(dst.info.packageName, dst.info.name);
mProviderMap.putProviderByClass(comp, dst);
调用contentprovider：
当调用ContentProvider的insert、delete、update、query方法中的任何一个时，如果ContentProvider所在的进程没有启动的话，
那么就会触发ContentProvider的创建，并伴随着ContentProvider所在进程的启动。
1. ApplicationContentResolver.acquireProvider:
holder = ActivityManagerNative.getDefault().getContentProvider(
getApplicationThread(), auth, userId, stable); //从AMS获取contentprovider的binder
2. ActivityManagerService.getContentProviderImpl
//先从mProviderMap中找已经publish的provider 返回这个provider
ContentProviderRecord cpr = mProviderMap.getProviderByName(name, userId);
//如果cpr不存在
ProviderInfo cpi = AppGlobals.getPackageManager().resolveContentProvider(name, STOCK_PM_FLAGS | PackageManager.GET_URI_PERMISSION_PATTERNS, UserHandle.USER_OWNER);
cpr = new ContentProviderRecord(this, cpi, ai, comp, singleton);
//获取provider所在进程
ProcessRecord proc = getProcessRecordLocked(cpi.processName, cpr.appInfo.uid, false);
if (proc != null && proc.thread != null) {
//如果已启动
proc.thread.scheduleInstallProvider(cpi);
} else {
proc = startProcessLocked(cpi.processName,
cpr.appInfo, false, 0, "content provider",
new ComponentName(cpi.applicationInfo.packageName,
cpi.name), false, false, false);
}
//等待直到provider publish成功