我们发现这里已经调用了我们平时见得很多在Application里面的attachBaseContext(context)方法
8、再来分析ContentProvider的调用,我们看下这个installContentProviders(app, providers)这个函数，这里providers是携带过来的数据，方法实现如下
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) { } }
我们可以看到这里调用了installProvider函数，我们看下这个函数的调用，在ActivityThread.java文件里面
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); }
我们可以看到返回对象是IActivityManager.ContentProviderHolder，然后这里先获取相应的Context上下文信息，然后ClassLoader加载对应的ContentProvider类，并创建该类的对象，然后我们调用了如下函数，参数是上下文，和函数传递进来的
ProviderInfo.
localProvider.attachInfo(c, info);
然后我们跟踪这个函数到里面去，(在ContentProvider类文件里面)代码如下，
public void attachInfo(Context context, ProviderInfo info) { attachInfo(context, info, false); }
继续跟踪这个函数attachInfo函数
private void attachInfo(Context context, ProviderInfo info, boolean testing) { 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; mSingleUser = (info.flags & ProviderInfo.FLAG_SINGLE_USER) != 0; setAuthorities(info.authority); } ContentProvider.this.onCreate(); } }
很明显这里调用的ContentProvider的onCreate函数，也就是我们平时见到的继承ContentProvider类的onCreate函数，这里ContentProvider就创建完了。
然后installProvider方法还有部分如下
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; }
获取ContetProvider的IContentProvider赋值给provider变量,然后调用
IBinder jBinder = provider.asBinder();
IContentProvider可以理解为ContentProvider客户端和服务端通信的接口，这里根据ProviderInfo的信息和Binder类型IContentProvider对象，创建一个ContentProviderHolder对象，它里边封装了这个ContentProvider的ProviderInfo和IContentProvider信息，然后又调用了下面的方法，我们跟踪进去
private ProviderClientRecord installProviderAuthoritiesLocked(IContentProvider provider, ContentProvider localProvider, IActivityManager.ContentProviderHolder holder) { final String auths[] = holder.info.authority.split(";"); final int userId = UserHandle.getUserId(holder.info.applicationInfo.uid); final ProviderClientRecord pcr = new ProviderClientRecord( auths, provider, localProvider, holder); for (String auth : auths) { final ProviderKey key = new ProviderKey(auth, userId); final ProviderClientRecord existing = mProviderMap.get(key); if (existing != null) { Slog.w(TAG, "Content provider " + pcr.mHolder.info.name + " already published as " + auth); } else { mProviderMap.put(key, pcr); } } return pcr; }
然后这里根据Provider的信息构造了ProviderClientRecord对象，authority是一个多属性值，变量这个Provider对应的所有authority,每个authority属性为key,保存这个ProviderClientReocrd到mProviderMap的HashMap中
我们可以看下这个地方本地声明的缓存存储信息，在ActivityThread.java这个类文件中
// The lock of mProviderMap protects the following variables. final ArrayMap<ProviderKey, ProviderClientRecord> mProviderMap = new ArrayMap<ProviderKey, ProviderClientRecord>(); final ArrayMap<IBinder, ProviderRefCount> mProviderRefCountMap = new ArrayMap<IBinder, ProviderRefCount>(); final ArrayMap<IBinder, ProviderClientRecord> mLocalProviders = new ArrayMap<IBinder, ProviderClientRecord>(); final ArrayMap<ComponentName, ProviderClientRecord> mLocalProvidersByName = new ArrayMap<ComponentName, ProviderClientRecord>();
