關(guān)鍵組件:
ContentResolver
ContentService
SyncManager
SyncManager.ActiveSyncContext
SyncManager.SyncOperation
SyncManager.SyncHandler
ContentResolver
外部的應(yīng)用程序通過調(diào)用ContentResolve.requestSync()靜態(tài)方法發(fā)起同步:
[java]
/**
?* @param account which account should be synced
?* @param authority which authority should be synced
?* @param extras any extras to pass to the SyncAdapter.
?*/?
public static void requestSync(Account account, String authority, Bundle extras) {?
??? validateSyncExtrasBundle(extras);?
??? try {?
??????? getContentService().requestSync(account, authority, extras);?
??? } catch (RemoteException e) {?
??? }?
}?
??? /**
???? * @param account which account should be synced
???? * @param authority which authority should be synced
???? * @param extras any extras to pass to the SyncAdapter.
???? */
??? public static void requestSync(Account account, String authority, Bundle extras) {
??????? validateSyncExtrasBundle(extras);
??????? try {
??????????? getContentService().requestSync(account, authority, extras);
??????? } catch (RemoteException e) {
??????? }
??? }
方法接收三個(gè)參數(shù):
- account:需要同步的帳號
- authority:需要進(jìn)行同步的authority
- extras:需要傳遞給sync adapter的附加數(shù)據(jù)
在這里,getContentService()方法返回系統(tǒng)服務(wù)ContentService的代理對象,然后通過它遠(yuǎn)程調(diào)用ContentService.requestSync()。
ContentService
ContentService是Android的系統(tǒng)服務(wù)裁替,它提供一系列數(shù)據(jù)同步及數(shù)據(jù)訪問等相關(guān)的操作朴恳。它的行為在IContentService.aidl中描述瞄勾。
這里帕胆,通過遠(yuǎn)程調(diào)用ContentService.requestSync()方法來啟動(dòng)針對指定帳號(account)的指定內(nèi)容(authority)的同步:
[java]
public void requestSync(Account account, String authority, Bundle extras) {?
??? ...?
??? try {?
??????? SyncManager syncManager = getSyncManager();?
??????? if (syncManager != null) {?
???????????
syncManager.scheduleSync(account, userId, authority, extras, 0 /* no
delay */,?
???????????????????
false /* onlyThoseWithUnkownSyncableState */);?
??????? }?
??? }?
??? ...?
}?
??? public void requestSync(Account account, String authority, Bundle extras) {
??????? ...
??????? try {
??????????? SyncManager syncManager = getSyncManager();
??????????? if (syncManager != null) {
???????????????
syncManager.scheduleSync(account, userId, authority, extras, 0 /* no
delay */,
???????????????????????
false /* onlyThoseWithUnkownSyncableState */);
??????????? }
??????? }
??????? ...
??? }
在這個(gè)方法中,會(huì)獲取一個(gè)SyncManager類的實(shí)例鹤盒。顧名思義,SyncManager管理與同步相關(guān)的處理侦副。
SyncManager
[java]
public void scheduleSync(Account requestedAccount, int userId, String requestedAuthority,?
??????? Bundle extras, long delay, boolean onlyThoseWithUnkownSyncableState) {?
??? ...?
??? final boolean backgroundDataUsageAllowed = !mBootCompleted ||?
??????????? getConnectivityManager().getBackgroundDataSetting();?
??? ...?
?????
??? // 產(chǎn)生一個(gè)同步帳戶列表昨悼。對于手動(dòng)同步,列表中僅有一個(gè)AccountUser元素跃洛,它封裝了需要同步的帳號以及對應(yīng)的應(yīng)用程序(userId)??
??? AccountAndUser[] accounts;?
??? if (requestedAccount != null && userId != UserHandle.USER_ALL) {?
??????? accounts = new
AccountAndUser[] { new AccountAndUser(requestedAccount, userId) };?
??? }?
??? ...?
??? for (AccountAndUser account : accounts) {?
??????? // 在這里率触,會(huì)掃描系統(tǒng)中所有提供了sync adapter的service:根據(jù)intent filter??
??????? // 然后從得到service
info中取得各自的authority。service info從對應(yīng)服務(wù)的meta-data標(biāo)簽中指定的sync
adapter描述文件中解析出來汇竭。??
??????? final HashSet<String> syncableAuthorities = new HashSet<String>();?
??????? for (RegisteredServicesCache.ServiceInfo<SyncAdapterType> syncAdapter :?
???????????????
mSyncAdapters.getAllServices(account.userId)) {?
??????????? syncableAuthorities.add(syncAdapter.type.authority);?
??????? }?
?
??????? ...?
?
??????? for (String authority : syncableAuthorities) {?
??????????? // 檢查帳戶是否能夠同步??
??????????? int
isSyncable = mSyncStorageEngine.getIsSyncable(account.account,
account.userId,?
???????????????????
authority);?
??????????? if (isSyncable == 0) {?
??????????????? continue;?
??????????? }?
??????????? final
RegisteredServicesCache.ServiceInfo<SyncAdapterType>
syncAdapterInfo;?
??????????? syncAdapterInfo = mSyncAdapters.getServiceInfo(?
???????????????????
SyncAdapterType.newKey(authority, account.account.type),
account.userId);?
??????????? ...?
?
??????????? if (isSyncable < 0) {?
???????????????
Bundle newExtras = new Bundle();?
???????????????
newExtras.putBoolean(ContentResolver.SYNC_EXTRAS_INITIALIZE,
true);?
??????????????? ...?
??????????????? // 部署同步操作??
??????????????? scheduleSyncOperation(?
???????????????????????
new SyncOperation(account.account, account.userId, source,
authority,?
???????????????????????????????
newExtras, 0, backoffTime, delayUntil, allowParallelSyncs));?
??????????? }?
??????????? ...?
??????? }?
??? }?
}?
??? public void scheduleSync(Account requestedAccount, int userId, String requestedAuthority,
???????????
Bundle extras, long delay, boolean onlyThoseWithUnkownSyncableState) {
??????? ...
??????? final boolean backgroundDataUsageAllowed = !mBootCompleted ||
???????????????
getConnectivityManager().getBackgroundDataSetting();
??????? ...
???????
??????? // 產(chǎn)生一個(gè)同步帳戶列表葱蝗。對于手動(dòng)同步,列表中僅有一個(gè)AccountUser元素细燎,它封裝了需要同步的帳號以及對應(yīng)的應(yīng)用程序(userId)
??????? AccountAndUser[] accounts;
??????? if (requestedAccount != null && userId != UserHandle.USER_ALL) {
???????????
accounts = new AccountAndUser[] { new AccountAndUser(requestedAccount,
userId) };
??????? }
??????? ...
??????? for (AccountAndUser account : accounts) {
??????????? // 在這里两曼,會(huì)掃描系統(tǒng)中所有提供了sync adapter的service:根據(jù)intent filter
??????????? //
然后從得到service info中取得各自的authority。service info從對應(yīng)服務(wù)的meta-data標(biāo)簽中指定的sync
adapter描述文件中解析出來玻驻。
??????????? final
HashSet<String> syncableAuthorities = new
HashSet<String>();
??????????? for
(RegisteredServicesCache.ServiceInfo<SyncAdapterType> syncAdapter :
???????????????????
mSyncAdapters.getAllServices(account.userId)) {
???????????????
syncableAuthorities.add(syncAdapter.type.authority);
??????????? }
??????????? ...
??????????? for (String authority : syncableAuthorities) {
??????????????? // 檢查帳戶是否能夠同步
???????????????
int isSyncable = mSyncStorageEngine.getIsSyncable(account.account,
account.userId,
???????????????????????
authority);
??????????????? if (isSyncable == 0) {
??????????????????? continue;
??????????????? }
???????????????
final RegisteredServicesCache.ServiceInfo<SyncAdapterType>
syncAdapterInfo;
???????????????
syncAdapterInfo = mSyncAdapters.getServiceInfo(
???????????????????????
SyncAdapterType.newKey(authority, account.account.type),
account.userId);
??????????????? ...
??????????????? if (isSyncable < 0) {
???????????????????
Bundle newExtras = new Bundle();
???????????????????
newExtras.putBoolean(ContentResolver.SYNC_EXTRAS_INITIALIZE, true);
??????????????????? ...
??????????????????? // 部署同步操作
???????????????????
scheduleSyncOperation(
???????????????????????????
new SyncOperation(account.account, account.userId, source, authority,
???????????????????????????????????
newExtras, 0, backoffTime, delayUntil, allowParallelSyncs));
??????????????? }
??????????????? ...
??????????? }
??????? }
??? }
這里悼凑,首先從系統(tǒng)中篩選出符合限定條件的service的信息,然后發(fā)起對應(yīng)的同步璧瞬。
首先為每一個(gè)同步操作生成一個(gè)SyncOperation實(shí)例户辫,它封裝了同步操作需要的全部信息:
[java]
public class SyncOperation implements Comparable {?
??? public final Account account;?
??? public final int userId;?
??? public int syncSource;?
??? public String authority;?
??? public final boolean allowParallelSyncs;?
??? public Bundle extras;?
??? public final String key;?
??? public long earliestRunTime;?
??? public boolean expedited;?
??? public SyncStorageEngine.PendingOperation pendingOperation;?
??? public Long backoff;?
??? public long delayUntil;?
??? public long effectiveRunTime;?
public class SyncOperation implements Comparable {
??? public final Account account;
??? public final int userId;
??? public int syncSource;
??? public String authority;
??? public final boolean allowParallelSyncs;
??? public Bundle extras;
??? public final String key;
??? public long earliestRunTime;
??? public boolean expedited;
??? public SyncStorageEngine.PendingOperation pendingOperation;
??? public Long backoff;
??? public long delayUntil;
??? public long effectiveRunTime;
然后調(diào)用scheduleSyncOperation方法:
[java]
public void scheduleSyncOperation(SyncOperation syncOperation) {?
??? boolean queueChanged;?
??? synchronized (mSyncQueue) {?
??????? queueChanged = mSyncQueue.add(syncOperation);?
??? }?
?
??? if (queueChanged) {?
??????? ...?
??????? sendCheckAlarmsMessage();?
??? }?
??? ...?
}?
??? public void scheduleSyncOperation(SyncOperation syncOperation) {
??????? boolean queueChanged;
??????? synchronized (mSyncQueue) {
??????????? queueChanged = mSyncQueue.add(syncOperation);
??????? }
??????? if (queueChanged) {
??????????? ...
??????????? sendCheckAlarmsMessage();
??????? }
??????? ...
??? }
首先將SyncOperation實(shí)例插入隊(duì)列mSyncQueue然后向SyncManager中定義的SyncHandler發(fā)送消息,通知其隊(duì)列發(fā)生變化:
[java]
private void sendCheckAlarmsMessage() {?
??? ...?
??? mSyncHandler.removeMessages(SyncHandler.MESSAGE_CHECK_ALARMS);?
??? mSyncHandler.sendEmptyMessage(SyncHandler.MESSAGE_CHECK_ALARMS);?
}?
??? private void sendCheckAlarmsMessage() {
??????? ...
??????? mSyncHandler.removeMessages(SyncHandler.MESSAGE_CHECK_ALARMS);
??????? mSyncHandler.sendEmptyMessage(SyncHandler.MESSAGE_CHECK_ALARMS);
??? }
隨后嗤锉,SyncHandler處理這個(gè)消息:
[java] v
public void handleMessage(Message msg) {?
???? ...?
???? try {?
???????? ...?
???????? switch (msg.what) {?
???????????? ...?
???????????? case SyncHandler.MESSAGE_CHECK_ALARMS:?
???????????????? ...?
????????????????
nextPendingSyncTime = maybeStartNextSyncLocked();?
???????????????? break;?
???????? }?
???? }?
???? ...?
?}?
?????? public void handleMessage(Message msg) {
??????????? ...
??????????? try {
??????????????? ...
??????????????? switch (msg.what) {
??????????????????? ...
???????????????????
case SyncHandler.MESSAGE_CHECK_ALARMS:
???????????????????????
...
???????????????????????
nextPendingSyncTime = maybeStartNextSyncLocked();
???????????????????????
break;
??????????????? }
??????????? }
??????????? ...
??????? }
這里渔欢,maybeStartNextSyncLocked()方法經(jīng)過一系列的檢查,確認(rèn)執(zhí)行同步的全部條件已經(jīng)達(dá)到之后瘟忱,對SyncOperation進(jìn)行分發(fā):
[java]
private long maybeStartNextSyncLocked() {?
??????? ...?
??????? dispatchSyncOperation(candidate);?
??? }?
?
??? return nextReadyToRunTime;?
}?
??????? private long maybeStartNextSyncLocked() {
??????????????? ...
??????????????? dispatchSyncOperation(candidate);
??????????? }
??????????? return nextReadyToRunTime;
??????? }
接下來奥额,將綁定到提供sync adapter的應(yīng)用程序中對應(yīng)的service:
[java]
private boolean dispatchSyncOperation(SyncOperation op) {?
??? ...?
??? // connect to the sync adapter??
??? SyncAdapterType syncAdapterType = SyncAdapterType.newKey(op.authority, op.account.type);?
??? final RegisteredServicesCache.ServiceInfo<SyncAdapterType> syncAdapterInfo;?
??? syncAdapterInfo = mSyncAdapters.getServiceInfo(syncAdapterType, op.userId);?
??? ...?
?
??? ActiveSyncContext activeSyncContext =?
??????????? new
ActiveSyncContext(op, insertStartSyncEvent(op),
syncAdapterInfo.uid);?
??? activeSyncContext.mSyncInfo = mSyncStorageEngine.addActiveSync(activeSyncContext);?
??? mActiveSyncContexts.add(activeSyncContext);?
??? ...?
??? if (!activeSyncContext.bindToSyncAdapter(syncAdapterInfo, op.userId)) {?
??????? Log.e(TAG, "Bind attempt failed to " + syncAdapterInfo);?
??????? closeActiveSyncContext(activeSyncContext);?
??????? return false;?
??? }?
?
??? return true;?
}?
??????? private boolean dispatchSyncOperation(SyncOperation op) {
??????????? ...
??????????? // connect to the sync adapter
???????????
SyncAdapterType syncAdapterType = SyncAdapterType.newKey(op.authority,
op.account.type);
??????????? final
RegisteredServicesCache.ServiceInfo<SyncAdapterType>
syncAdapterInfo;
???????????
syncAdapterInfo = mSyncAdapters.getServiceInfo(syncAdapterType,
op.userId);
??????????? ...
??????????? ActiveSyncContext activeSyncContext =
???????????????????
new ActiveSyncContext(op, insertStartSyncEvent(op),
syncAdapterInfo.uid);
???????????
activeSyncContext.mSyncInfo =
mSyncStorageEngine.addActiveSync(activeSyncContext);
??????????? mActiveSyncContexts.add(activeSyncContext);
??????????? ...
??????????? if
(!activeSyncContext.bindToSyncAdapter(syncAdapterInfo, op.userId)) {
???????????????
Log.e(TAG, "Bind attempt failed to " + syncAdapterInfo);
???????????????
closeActiveSyncContext(activeSyncContext);
??????????????? return false;
??????????? }
??????????? return true;
??????? }
與前面的AccountManager非常的雷同,這里通過ActiveSyncContext類來完成service的綁定:
[java]
class ActiveSyncContext extends ISyncContext.Stub?
??????? implements ServiceConnection, IBinder.DeathRecipient {?
??? ...?
??? public void onServiceConnected(ComponentName name, IBinder service) {?
??????? Message msg = mSyncHandler.obtainMessage();?
??????? msg.what = SyncHandler.MESSAGE_SERVICE_CONNECTED;?
??????? msg.obj = new
ServiceConnectionData(this,
ISyncAdapter.Stub.asInterface(service));?
??????? mSyncHandler.sendMessage(msg);?
??? }?
??? ...?
??? boolean bindToSyncAdapter(RegisteredServicesCache.ServiceInfo info, int userId) {?
??????? if (Log.isLoggable(TAG, Log.VERBOSE)) {?
???????????
Log.d(TAG, "bindToSyncAdapter: " + info.componentName + ", connection " +
this);?
??????? }?
??????? Intent intent = new Intent();?
??????? intent.setAction("android.content.SyncAdapter");?
??????? intent.setComponent(info.componentName);?
??????? intent.putExtra(Intent.EXTRA_CLIENT_LABEL,?
???????????????
com.android.internal.R.string.sync_binding_label);?
??????? intent.putExtra(Intent.EXTRA_CLIENT_INTENT, PendingIntent.getActivityAsUser(?
???????????????
mContext, 0, new Intent(Settings.ACTION_SYNC_SETTINGS), 0,?
??????????????? null, new UserHandle(userId)));?
??????? mBound = true;?
??????? final boolean bindResult = mContext.bindService(intent, this,?
???????????????
Context.BIND_AUTO_CREATE | Context.BIND_NOT_FOREGROUND?
???????????????
| Context.BIND_ALLOW_OOM_MANAGEMENT,?
??????????????? mSyncOperation.userId);?
??????? if (!bindResult) {?
??????????? mBound = false;?
??????? }?
??????? return bindResult;?
??? }?
??? ...?
}?
??? class ActiveSyncContext extends ISyncContext.Stub
??????????? implements ServiceConnection, IBinder.DeathRecipient {
??????? ...
??????? public void onServiceConnected(ComponentName name, IBinder service) {
??????????? Message msg = mSyncHandler.obtainMessage();
??????????? msg.what = SyncHandler.MESSAGE_SERVICE_CONNECTED;
???????????
msg.obj = new ServiceConnectionData(this,
ISyncAdapter.Stub.asInterface(service));
??????????? mSyncHandler.sendMessage(msg);
??????? }
??????? ...
??????? boolean bindToSyncAdapter(RegisteredServicesCache.ServiceInfo info, int userId) {
??????????? if (Log.isLoggable(TAG, Log.VERBOSE)) {
???????????????
Log.d(TAG, "bindToSyncAdapter: " + info.componentName + ", connection "
+ this);
??????????? }
??????????? Intent intent = new Intent();
??????????? intent.setAction("android.content.SyncAdapter");
??????????? intent.setComponent(info.componentName);
??????????? intent.putExtra(Intent.EXTRA_CLIENT_LABEL,
???????????????????
com.android.internal.R.string.sync_binding_label);
???????????
intent.putExtra(Intent.EXTRA_CLIENT_INTENT,
PendingIntent.getActivityAsUser(
???????????????????
mContext, 0, new Intent(Settings.ACTION_SYNC_SETTINGS), 0,
???????????????????
null, new UserHandle(userId)));
??????????? mBound = true;
??????????? final boolean bindResult = mContext.bindService(intent, this,
???????????????????
Context.BIND_AUTO_CREATE | Context.BIND_NOT_FOREGROUND
???????????????????
| Context.BIND_ALLOW_OOM_MANAGEMENT,
???????????????????
mSyncOperation.userId);
??????????? if (!bindResult) {
??????????????? mBound = false;
??????????? }
??????????? return bindResult;
??????? }
??????? ...
??? }其中访诱,bindToSyncAdapter()中創(chuàng)建相應(yīng)的Intent垫挨,發(fā)起綁定。
然后触菜,因?yàn)楸绢悓?shí)現(xiàn)了ServiceConnection接口九榔,所以當(dāng)綁定成功時(shí),將回調(diào)本類的onServiceConnected()方法。在這個(gè)回調(diào)中帚屉,向SyncHandler發(fā)送一條MESSAGE_SERVICE_CONNECTED消息谜诫。
緊接著,輪到SyncHandler來處理消息:
case SyncHandler.MESSAGE_SERVICE_CONNECTED: {?
??? ServiceConnectionData msgData = (ServiceConnectionData)msg.obj;?
??? if (Log.isLoggable(TAG, Log.VERBOSE)) {?
??????? Log.d(TAG, "handleSyncHandlerMessage: MESSAGE_SERVICE_CONNECTED: "?
??????????????? + msgData.activeSyncContext);?
??? }?
??? // check that this isn't an old message??
??? if (isSyncStillActive(msgData.activeSyncContext)) {?
??????? runBoundToSyncAdapter(msgData.activeSyncContext, msgData.syncAdapter);?
??? }?
??? break;?
}?
???????????????????
case SyncHandler.MESSAGE_SERVICE_CONNECTED: {
???????????????????????
ServiceConnectionData msgData = (ServiceConnectionData)msg.obj;
???????????????????????
if (Log.isLoggable(TAG, Log.VERBOSE)) {
???????????????????????????
Log.d(TAG, "handleSyncHandlerMessage: MESSAGE_SERVICE_CONNECTED: "
???????????????????????????????????
+ msgData.activeSyncContext);
???????????????????????
}
???????????????????????
// check that this isn't an old message
???????????????????????
if (isSyncStillActive(msgData.activeSyncContext)) {
???????????????????????????
runBoundToSyncAdapter(msgData.activeSyncContext, msgData.syncAdapter);
???????????????????????
}
???????????????????????
break;
??????????????????? }
這里主要就是調(diào)用了runBoundToSyncAdapter()方法:
[java]
private void runBoundToSyncAdapter(final ActiveSyncContext activeSyncContext,?
????? ISyncAdapter syncAdapter) {?
??? activeSyncContext.mSyncAdapter = syncAdapter;?
??? final SyncOperation syncOperation = activeSyncContext.mSyncOperation;?
??? try {?
??????? ...?
??????? syncAdapter.startSync(activeSyncContext, syncOperation.authority,?
???????????????
syncOperation.account, syncOperation.extras);?
??? }?
??? ...?
}?