android同步操作框架

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(hào)

- 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)

在這里训貌,getContentService()方法返回系統(tǒng)服務(wù)ContentService的代理對象扶歪,然后通過它遠(yuǎn)程調(diào)用ContentService.requestSync()北专。

ContentService

ContentService是Android系統(tǒng)服務(wù)吼和,它提供一系列數(shù)據(jù)同步及數(shù)據(jù)訪問等相關(guān)的操作兼蕊。它的行為在IContentService.aidl中描述。

這里,通過遠(yuǎn)程調(diào)用ContentService.requestSync()方法來啟動(dòng)針對指定帳號(hào)(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)方法中砌函,會(huì)獲取一個(gè)SyncManager類的實(shí)例。顧名思義,SyncManager管理與同步相關(guān)的處理讹俊。

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)同步帳戶列表垦沉。對于手動(dòng)同步,列表中僅有一個(gè)AccountUser元素仍劈,它封裝了需要同步的帳號(hào)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) {

// 在這里厕倍,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贩疙。

final HashSet syncableAuthorities = new HashSet();

for (RegisteredServicesCache.ServiceInfo 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 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)同步帳戶列表绑青。對于手動(dòng)同步,列表中僅有一個(gè)AccountUser元素屋群,它封裝了需要同步的帳號(hào)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) {

// 在這里闸婴,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芍躏。

final HashSet syncableAuthorities = new HashSet();

for (RegisteredServicesCache.ServiceInfo 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 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));

}

...

}

}

}

這里邪乍,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)的同步对竣。

首先為每一個(gè)同步操作生成一個(gè)SyncOperation實(shí)例庇楞,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);

}

隨后否纬,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;

}

}

...

}

這里吕晌,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)到之后临燃,對SyncOperation進(jìn)行分發(fā):

[java]

private long maybeStartNextSyncLocked() {

...

dispatchSyncOperation(candidate);

}

return nextReadyToRunTime;

}

private long maybeStartNextSyncLocked() {

...

dispatchSyncOperation(candidate);

}

return nextReadyToRunTime;

}

接下來睛驳,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 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 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;

}

...

}其中膜廊,bindToSyncAdapter()中創(chuàng)建相應(yīng)的Intent乏沸,發(fā)起綁定。

然后爪瓜,因?yàn)楸绢悓?shí)現(xiàn)了ServiceConnection接口蹬跃,所以當(dāng)綁定成功時(shí),將回調(diào)本類的onServiceConnected()方法铆铆。在這個(gè)回調(diào)中蝶缀,向SyncHandler發(fā)送一條MESSAGE_SERVICE_CONNECTED消息。

緊接著薄货,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);

}

...

}

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