Android -- NetworkFactory与NetworkAgent的通信机制
在上一篇博文中讲到,EthernetNetworkFactory包揽了Ethernet所有的网络管理操作,这其中就包含怎么样通知ConnectifyService(下文都简称CS)网络状态发生变化。接下来,我们借助有线网络来简要介绍Android 4.4之后,网络模块是怎样与CS通信并进行网络管理的。
在启动Ethernet网络服务时,我们会对Ethernet做一些初始化操作,以方便我们进行网络管理。
看EthernetNetworkFactory::start()方法:
/**
* Begin monitoring connectivity
*/
public synchronized void start(Context context, Handler target) {
// The services we use.
IBinder b = ServiceManager.getService(Context.NETWORKMANAGEMENT_SERVICE);
mNMService = INetworkManagementService.Stub.asInterface(b);
mEthernetManager = (EthernetManager) context.getSystemService(Context.ETHERNET_SERVICE);
// Interface match regex.
mIfaceMatch = context.getResources().getString(
com.android.internal.R.string.config_ethernet_iface_regex);
// Create and register our NetworkFactory.
mFactory = new LocalNetworkFactory(NETWORK_TYPE, context, target.getLooper());
mFactory.setCapabilityFilter(mNetworkCapabilities);
mFactory.setScoreFilter(-1); // this set high when we have an iface
mFactory.register();
mContext = context;
// Start tracking interface change events.
mInterfaceObserver = new InterfaceObserver();
try {
mNMService.registerObserver(mInterfaceObserver);
} catch (RemoteException e) {
Log.e(TAG, "Could not register InterfaceObserver " + e);
}
// If an Ethernet interface is already connected, start tracking that.
// Otherwise, the first Ethernet interface to appear will be tracked.
try {
final String[] ifaces = mNMService.listInterfaces();
for (String iface : ifaces) {
synchronized(this) {
if (maybeTrackInterface(iface)) {
// We have our interface. Track it.
// Note: if the interface already has link (e.g., if we
// crashed and got restarted while it was running),
// we need to fake a link up notification so we start
// configuring it. Since we're already holding the lock,
// any real link up/down notification will only arrive
// after we've done this.
if (mNMService.getInterfaceConfig(iface).hasFlag("running")) {
updateInterfaceState(iface, true);
}
break;
}
}
}
} catch (RemoteException e) {
Log.e(TAG, "Could not get list of interfaces " + e);
}
}
start()方法接受一个Handler对象作为参数,该参数是在EthernetServiceImpl::start()中传入的,它新建了一个HandlerThread对象,并传入作为参数,从这可知网络管理的操作是运行在EthernetServiceImpl线程中的。
代码中创建了一个LocalNetworkFactory对象。LocalNetworkFactory继承自NetworkFactory:
/**
* A NetworkFactory is an entity that creates NetworkAgent objects.
* The bearers register with ConnectivityService using {@link #register} and
* their factory will start receiving scored NetworkRequests. NetworkRequests
* can be filtered 3 ways: by NetworkCapabilities, by score and more complexly by
* overridden function. All of these can be dynamic - changing NetworkCapabilities
* or score forces re-evaluation of all current requests.
*
* If any requests pass the filter some overrideable functions will be called.
* If the bearer only cares about very simple start/stopNetwork callbacks, those
* functions can be overridden. If the bearer needs more interaction, it can
* override addNetworkRequest and removeNetworkRequest which will give it each
* request that passes their current filters.
* @hide
**/
public class NetworkFactory extends Handler {
...
public NetworkFactory(Looper looper, Context context, String logTag,
NetworkCapabilities filter) {
super(looper);
LOG_TAG = logTag;
mContext = context;
mCapabilityFilter = filter;
}
...
public void register() {
if (DBG) log("Registering NetworkFactory");
if (mMessenger == null) {
mMessenger = new Messenger(this);
ConnectivityManager.from(mContext).registerNetworkFactory(mMessenger, LOG_TAG);
}
}
...
// override to do simple mode (request independent)
protected void startNetwork() { }
protected void stopNetwork() { }
...
}
NetworkFactory继承自Handler,我们可以把它动作一个工厂,对网络的请求和终止操作都通过该对象进行处理。从注释可知NetworkFactory与NetworkAgent对象有密切关系,它通过register()方法向CS进行注册。start/stopNetwork()是提供的回调函数 ,我们可以通过这两个函数来请求或终止网络:
public void register() {
if (DBG) log("Registering NetworkFactory");
if (mMessenger == null) {
mMessenger = new Messenger(this);
ConnectivityManager.from(mContext).registerNetworkFactory(mMessenger, LOG_TAG);
}
}
创建NetworkFactory对象时,我们给它指定了一个特定线程的Looper对象;接着调用register()方法向CS注册这个NetworkFactory对象,实际是调用CS中的registerNetworkFactory()方法:
@Override
public void registerNetworkFactory(Messenger messenger, String name) {
enforceConnectivityInternalPermission();
NetworkFactoryInfo nfi = new NetworkFactoryInfo(name, messenger, new AsyncChannel());
mHandler.sendMessage(mHandler.obtainMessage(EVENT_REGISTER_NETWORK_FACTORY, nfi));
}
参数Messenger对象是一个可以跨进程传递的实例对象,它实际代表一个Handler对象,我们可以像使用Handler对象一样,使用Messenger对象来发送消息;此处该引用指向mNetworkFactory这个Handler对象,它绑定的Looper属于一个特定的线程,它在EthernetServiceImpl中创建。
看NetworkFactoryInfo,它是一个CS中的内部类,保存了特定的Messager对象和一个与之关联的AsyncChannel对象。看到此处我们知道这里会通过异步通道来进行消息传递的。
接着会发送一个EVENT_REGISTER_NETWORK_FACTORY消息,它被CS中的InternalHandler处理,这个Handler主要完成CS内部消息事件的处理。我们直接看处理过程:
case EVENT_REGISTER_NETWORK_FACTORY: {
handleRegisterNetworkFactory((NetworkFactoryInfo)msg.obj);
break;
}
private void handleRegisterNetworkFactory(NetworkFactoryInfo nfi) {
if (DBG) log("Got NetworkFactory Messenger for " + nfi.name);
mNetworkFactoryInfos.put(nfi.messenger, nfi);
nfi.asyncChannel.connect(mContext, mTrackerHandler, nfi.messenger);
}
异步通道的内容在以前的博文中已经讲过。先将之前创建的nfi对象以Messenger对象为key添加到mNetworkFactoryInfos中,它是一个HashMap对象,方便后面获取。再调用connect()方法进行AsyncChannel连接的创建:
/**
* Connect handler and messenger.
*
* Sends a CMD_CHANNEL_HALF_CONNECTED message to srcHandler when complete.
* msg.arg1 = status
* msg.obj = the AsyncChannel
*
* @param srcContext
* @param srcHandler
* @param dstMessenger
*/
public void connect(Context srcContext, Handler srcHandler, Messenger dstMessenger) {
if (DBG) log("connect srcHandler to the dstMessenger E");
// We are connected
connected(srcContext, srcHandler, dstMessenger);
// Tell source we are half connected
replyHalfConnected(STATUS_SUCCESSFUL);
if (DBG) log("connect srcHandler to the dstMessenger X");
}
/**
* Connect handler to messenger. This method is typically called
* when a server receives a CMD_CHANNEL_FULL_CONNECTION request
* and initializes the internal instance variables to allow communication
* with the dstMessenger.
*
* @param srcContext
* @param srcHandler
* @param dstMessenger
*/
public void connected(Context srcContext, Handler srcHandler, Messenger dstMessenger) {
if (DBG) log("connected srcHandler to the dstMessenger E");
// Initialize source fields
mSrcContext = srcContext;
mSrcHandler = srcHandler;
mSrcMessenger = new Messenger(mSrcHandler);
// Initialize destination fields
mDstMessenger = dstMessenger;
if (DBG) log("connected srcHandler to the dstMessenger X");
}
要明确的是,srcHandler指向CS中的NetworkStateTrackerHandler对象,它主要负责接收网络模块发送的消息,并进行网络更新;mSrcMessenger是代表该Handler对象的一个引用;mDstMessenger则代表EthernetNetworkFactory中的LocalNetworkFactory对象,该对象也是一个Handler。
然后向mSrcHandler回复CMD_CHANNEL_HALF_CONNECTED消息:
/**
* Reply to the src handler that we're half connected.
* see: CMD_CHANNEL_HALF_CONNECTED for message contents
*
* @param status to be stored in msg.arg1
*/
private void replyHalfConnected(int status) {
Message msg = mSrcHandler.obtainMessage(CMD_CHANNEL_HALF_CONNECTED);
msg.arg1 = status;
msg.obj = this;
msg.replyTo = mDstMessenger;
/*
* Link to death only when bindService isn't used.
*/
if (mConnection == null) {
mDeathMonitor = new DeathMonitor();
try {
mDstMessenger.getBinder().linkToDeath(mDeathMonitor, 0);//为了防止AsyncChannel用于不同进程通信时,若Server端所在的进程已经死掉,来通知
//Client端进程进行一些后期处理
} catch (RemoteException e) {
mDeathMonitor = null;
// Override status to indicate failure
msg.arg1 = STATUS_BINDING_UNSUCCESSFUL;
}
}
mSrcHandler.sendMessage(msg);
}
CS中是这样处理的:
case AsyncChannel.CMD_CHANNEL_HALF_CONNECTED: {
handleAsyncChannelHalfConnect(msg);
break;
}
private void handleAsyncChannelHalfConnect(Message msg) {
AsyncChannel ac = (AsyncChannel) msg.obj;
if (mNetworkFactoryInfos.containsKey(msg.replyTo)) {
if (msg.arg1 == AsyncChannel.STATUS_SUCCESSFUL) {
if (VDBG) log("NetworkFactory connected");
// A network factory has connected. Send it all current NetworkRequests.
for (NetworkRequestInfo nri : mNetworkRequests.values()) {
if (nri.isRequest == false) continue;
NetworkAgentInfo nai = mNetworkForRequestId.get(nri.request.requestId);
ac.sendMessage(android.net.NetworkFactory.CMD_REQUEST_NETWORK,
(nai != null ? nai.getCurrentScore() : 0), 0, nri.request);
}
} else {
loge("Error connecting NetworkFactory");
mNetworkFactoryInfos.remove(msg.obj);
}
} else if (mNetworkAgentInfos.containsKey(msg.replyTo)) {
if (msg.arg1 == AsyncChannel.STATUS_SUCCESSFUL) {
if (VDBG) log("NetworkAgent connected");
// A network agent has requested a connection. Establish the connection.
mNetworkAgentInfos.get(msg.replyTo).asyncChannel.
sendMessage(AsyncChannel.CMD_CHANNEL_FULL_CONNECTION);
} else {
loge("Error connecting NetworkAgent");
NetworkAgentInfo nai = mNetworkAgentInfos.remove(msg.replyTo);
if (nai != null) {
final boolean wasDefault = isDefaultNetwork(nai);
synchronized (mNetworkForNetId) {
mNetworkForNetId.remove(nai.network.netId);
mNetIdInUse.delete(nai.network.netId);
}
// Just in case.
mLegacyTypeTracker.remove(nai, wasDefault);
}
}
}
}
我们先前已经向mNetworkFactoryInfos集合添加过NetworkFactoryInfo对象,实际的处理是:
// A network factory has connected. Send it all current NetworkRequests.
for (NetworkRequestInfo nri : mNetworkRequests.values()) {
if (nri.isRequest == false) continue;
NetworkAgentInfo nai = mNetworkForRequestId.get(nri.request.requestId);
ac.sendMessage(android.net.NetworkFactory.CMD_REQUEST_NETWORK,
(nai != null ? nai.getCurrentScore() : 0), 0, nri.request);
}
直接看消息发送处理;通过AsyncChannel对象向mDstMessenger对象发送消息。根据前面所述,即向Ethernet中的LocalNetworkFactory发送CMD_REQUEST_NETWORK消息,表示当前系统要请求一个网络。
有前面可知父类NetworkFactory本身就是一个Handler,它处理该消息:
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case CMD_REQUEST_NETWORK: {
handleAddRequest((NetworkRequest)msg.obj, msg.arg1);
break;
}
case CMD_CANCEL_REQUEST: {
handleRemoveRequest((NetworkRequest) msg.obj);
break;
}
case CMD_SET_SCORE: {
handleSetScore(msg.arg1);
break;
}
case CMD_SET_FILTER: {
handleSetFilter((NetworkCapabilities) msg.obj);
break;
}
}
}
private void handleAddRequest(NetworkRequest request, int score) {
NetworkRequestInfo n = mNetworkRequests.get(request.requestId);
if (n == null) {
if (DBG) log("got request " + request + " with score " + score);
n = new NetworkRequestInfo(request, score);
mNetworkRequests.put(n.request.requestId, n);
} else {
if (VDBG) log("new score " + score + " for exisiting request " + request);
n.score = score;
}
if (VDBG) log(" my score=" + mScore + ", my filter=" + mCapabilityFilter);
evalRequest(n);
}
private void evalRequest(NetworkRequestInfo n) {
if (VDBG) log("evalRequest");
if (n.requested == false && n.score < mScore &&
n.request.networkCapabilities.satisfiedByNetworkCapabilities(
mCapabilityFilter) && acceptRequest(n.request, n.score)) {
if (VDBG) log(" needNetworkFor");
needNetworkFor(n.request, n.score);
n.requested = true;
} else if (n.requested == true &&
(n.score > mScore || n.request.networkCapabilities.satisfiedByNetworkCapabilities(
mCapabilityFilter) == false || acceptRequest(n.request, n.score) == false)) {
if (VDBG) log(" releaseNetworkFor");
releaseNetworkFor(n.request);
n.requested = false;
} else {
if (VDBG) log(" done");
}
}
如果消息附带的NetworkRequestInfo对象没有保存,则先保存到mNetworkRequests集合中,同时根据NetworkRequestInfo对象中的requested和score属性值,相应的调用needNetworkFor()或releaseNetworkFor():
// override to do fancier stuff
protected void needNetworkFor(NetworkRequest networkRequest, int score) {
if (++mRefCount == 1) startNetwork();
}
protected void releaseNetworkFor(NetworkRequest networkRequest) {
if (--mRefCount == 0) stopNetwork();
}
即调用LocalNetworkFactory中的start/stopNetwork()来管理网络的开启和关闭:
private class LocalNetworkFactory extends NetworkFactory {
LocalNetworkFactory(String name, Context context, Looper looper) {
super(looper, context, name, new NetworkCapabilities());
}
protected void startNetwork() {
onRequestNetwork();
}
protected void stopNetwork() {
}
}
onRequestNetwork()处理Ethernet的连接操作,包括对静态IP和DHCP的处理。到这里,一个NetworkFactory对象的注册过程就结束了。
我们看onRequestNetwork()方法来触发一个网络的连接:
/* Called by the NetworkFactory on the handler thread. */
public void onRequestNetwork() {
// TODO: Handle DHCP renew.
Thread dhcpThread = new Thread(new Runnable() {
public void run() {
if (DBG) Log.i(TAG, "dhcpThread(" + mIface + "): mNetworkInfo=" + mNetworkInfo);
LinkProperties linkProperties;
IpConfiguration config = mEthernetManager.getConfiguration();
if (config.getIpAssignment() == IpAssignment.STATIC) {
if (!setStaticIpAddress(config.getStaticIpConfiguration())) {
// We've already logged an error.
return;
}
linkProperties = config.getStaticIpConfiguration().toLinkProperties(mIface);
} else {
mNetworkInfo.setDetailedState(DetailedState.OBTAINING_IPADDR, null, mHwAddr);
DhcpResults dhcpResults = new DhcpResults();
// TODO: Handle DHCP renewals better.
// In general runDhcp handles DHCP renewals for us, because
// the dhcp client stays running, but if the renewal fails,
// we will lose our IP address and connectivity without
// noticing.
if (!NetworkUtils.runDhcp(mIface, dhcpResults)) {
Log.e(TAG, "DHCP request error:" + NetworkUtils.getDhcpError());
// set our score lower than any network could go
// so we get dropped.
mFactory.setScoreFilter(-1);
// If DHCP timed out (as opposed to failing), the DHCP client will still be
// running, because in M we changed its timeout to infinite. Stop it now.
NetworkUtils.stopDhcp(mIface);
return;
}
linkProperties = dhcpResults.toLinkProperties(mIface);
}
...
}
});
dhcpThread.start();
}
CS中处理网络更新的Handler是NetworkStateTrackerHandler。当网络连接后,通知CS更新网络的操作则是通过NetworkAgent对象进行的。从它的定义可知,它也是一个Handler:
synchronized(EthernetNetworkFactory.this) {
if (mNetworkAgent != null) {
Log.e(TAG, "Already have a NetworkAgent - aborting new request");
return;
}
mLinkProperties = linkProperties;
mNetworkInfo.setIsAvailable(true);
mNetworkInfo.setDetailedState(DetailedState.CONNECTED, null, mHwAddr);
// Create our NetworkAgent.
mNetworkAgent = new NetworkAgent(mFactory.getLooper(), mContext,
NETWORK_TYPE, mNetworkInfo, mNetworkCapabilities, mLinkProperties,
NETWORK_SCORE) {
public void unwanted() {
synchronized(EthernetNetworkFactory.this) {
if (this == mNetworkAgent) {
NetworkUtils.stopDhcp(mIface);
mLinkProperties.clear();
mNetworkInfo.setDetailedState(DetailedState.DISCONNECTED, null,
mHwAddr);
updateAgent();
mNetworkAgent = null;
try {
mNMService.clearInterfaceAddresses(mIface);
} catch (Exception e) {
Log.e(TAG, "Failed to clear addresses or disable ipv6" + e);
}
} else {
Log.d(TAG, "Ignoring unwanted as we have a more modern " +
"instance");
}
}
};
};
}
/**
* Called when ConnectivityService has indicated they no longer want this network.
* The parent factory should (previously) have received indication of the change
* as well, either canceling NetworkRequests or altering their score such that this
* network won't be immediately requested again.
*/
abstract protected void unwanted();
重写的unwanted()方法则在CS指出不再需要当前网络连接时调用。除了清除掉网络配置信息,还会把mNetworkAgent置为null。从代码中可以看出,mNetworkAgent是否为null标志了当前是否该类型的网络连接正在使用,如果有则不会处理新的网络请求。
既然网络状态的变化是由NetworkAgent处理的,那我们就接着看NetworkAgent是怎么跟CS通信的:
public NetworkAgent(Looper looper, Context context, String logTag, NetworkInfo ni,
NetworkCapabilities nc, LinkProperties lp, int score) {
this(looper, context, logTag, ni, nc, lp, score, null);
}
public NetworkAgent(Looper looper, Context context, String logTag, NetworkInfo ni,
NetworkCapabilities nc, LinkProperties lp, int score, NetworkMisc misc) {
super(looper);
LOG_TAG = logTag;
mContext = context;
if (ni == null || nc == null || lp == null) {
throw new IllegalArgumentException();
}
if (VDBG) log("Registering NetworkAgent");
ConnectivityManager cm = (ConnectivityManager)mContext.getSystemService(
Context.CONNECTIVITY_SERVICE);
netId = cm.registerNetworkAgent(new Messenger(this), new NetworkInfo(ni),
new LinkProperties(lp), new NetworkCapabilities(nc), score, misc);
}
在创建NetworkAgent对象时,接受一个特定的Looper对象,并向CS注册该NetworkAgent对象,这与LocalNetworkFactory的处理类似。看CS中具体的注册处理:
public int registerNetworkAgent(Messenger messenger, NetworkInfo networkInfo,
LinkProperties linkProperties, NetworkCapabilities networkCapabilities,
int currentScore, NetworkMisc networkMisc) {
enforceConnectivityInternalPermission();
// TODO: Instead of passing mDefaultRequest, provide an API to determine whether a Network
// satisfies mDefaultRequest.
final NetworkAgentInfo nai = new NetworkAgentInfo(messenger, new AsyncChannel(),
new Network(reserveNetId()), new NetworkInfo(networkInfo), new LinkProperties(
linkProperties), new NetworkCapabilities(networkCapabilities), currentScore,
mContext, mTrackerHandler, new NetworkMisc(networkMisc), mDefaultRequest, this);
synchronized (this) {
nai.networkMonitor.systemReady = mSystemReady;
}
addValidationLogs(nai.networkMonitor.getValidationLogs(), nai.network);
if (DBG) log("registerNetworkAgent " + nai);
mHandler.sendMessage(mHandler.obtainMessage(EVENT_REGISTER_NETWORK_AGENT, nai));
return nai.network.netId;
}
这里的Messager对象是NetworkAgent对象自身的一个引用,创建对应的NetworkAgentInfo对象,其内部创建了一个AsyncChannel对象;messenger参数前面介绍过,mTrackderHandler是NetworkStateTrackerHandler的一个实例。
向InternalHandler发送EVENT_REGISTER_NETWORK_AGENT消息,处理注册操作。看CS中的处理:
case EVENT_REGISTER_NETWORK_AGENT: {
handleRegisterNetworkAgent((NetworkAgentInfo)msg.obj);
break;
}
private void handleRegisterNetworkAgent(NetworkAgentInfo na) {
if (VDBG) log("Got NetworkAgent Messenger");
mNetworkAgentInfos.put(na.messenger, na);
synchronized (mNetworkForNetId) {
mNetworkForNetId.put(na.network.netId, na);
}
na.asyncChannel.connect(mContext, mTrackerHandler, na.messenger);
NetworkInfo networkInfo = na.networkInfo;
na.networkInfo = null;
updateNetworkInfo(na, networkInfo);//更新网络状态的函数
}
也是将na和messenger对象保存到一个HashMap集合中,也是通过AsyncChannel进行通信,也是调用connect()进行连接,这跟前面所述的NetworkFactory的处理基本类似。从前面的分析可知这个AsyncChannel对象中,mSrcHandler和mSrcMessenger指向一个CS中的NetworkStateTrackerHandler,mDstMessenger指向要注册的NetworkAgent对象,因为它本身也是个Handler。
接着向mSrcHandler发送CMD_CHANNEL_HALF_CONNECTED消息,同样也是handleAsyncChannelHalfConnect()处理,只不过走的处理分支不同,有前面的介绍可知:
if (VDBG) log("NetworkAgent connected");
// A network agent has requested a connection. Establish the connection.
mNetworkAgentInfos.get(msg.replyTo).asyncChannel.
sendMessage(AsyncChannel.CMD_CHANNEL_FULL_CONNECTION);
使用AsyncChannel向mDstMessenger发送CMD_CHANNEL_FULL_CONNECTION消息,即向NetworkAgent对象发送该消息:
case AsyncChannel.CMD_CHANNEL_FULL_CONNECTION: {
if (mAsyncChannel != null) {
log("Received new connection while already connected!");
} else {
if (VDBG) log("NetworkAgent fully connected");
AsyncChannel ac = new AsyncChannel();
ac.connected(null, this, msg.replyTo);
ac.replyToMessage(msg, AsyncChannel.CMD_CHANNEL_FULLY_CONNECTED,
AsyncChannel.STATUS_SUCCESSFUL);
synchronized (mPreConnectedQueue) {
mAsyncChannel = ac;
for (Message m : mPreConnectedQueue) {
ac.sendMessage(m);
}
mPreConnectedQueue.clear();
}
}
break;
}
如果当前NetworkAgent是第一次进行连接,mAsyncChannel为null;新建一个AsyncChannel对象,调用connected()进行FULL_CONNECTION:
public void connected(Context srcContext, Handler srcHandler, Messenger dstMessenger) {
if (DBG) log("connected srcHandler to the dstMessenger E");
// Initialize source fields
mSrcContext = srcContext;
mSrcHandler = srcHandler;
mSrcMessenger = new Messenger(mSrcHandler);
// Initialize destination fields
mDstMessenger = dstMessenger;
if (DBG) log("connected srcHandler to the dstMessenger X");
}
mSrcHandler和mSrcMessenger指向当前的NetworkAgent对象;mDstMessenger指向CS中的NetworkStateTrackerHandler对象。
随后再发送CMD_CHANNEL_FULLY_CONNECTED消息,表示整个AsyncChannel的连接成功,可以进行通信了。同时,还会遍历mPreConnectedQueue集合,这个集合中保存了当mAsyncChannel为null时的所有与更新网络信息相关的message,通过ac.sendMessage()向CS发送所有的message进行状态更新(要注意,ac对象的mSrcHanlder为当前NetworkAgent,mDstMessenger指向NetworkStateTrackerHandler)。
至此可知,我们通过NetworkAgent向CS报告网络的变化,通知它进行网络状态的更新。EthernetNetworkFactory中通过updateAgent()完成此项工作:
public void updateAgent() {
synchronized (EthernetNetworkFactory.this) {
if (mNetworkAgent == null) return;
if (DBG) {
Log.i(TAG, "Updating mNetworkAgent with: " +
mNetworkCapabilities + ", " +
mNetworkInfo + ", " +
mLinkProperties);
}
mNetworkAgent.sendNetworkCapabilities(mNetworkCapabilities);
mNetworkAgent.sendNetworkInfo(mNetworkInfo);
mNetworkAgent.sendLinkProperties(mLinkProperties);
// never set the network score below 0.
mNetworkAgent.sendNetworkScore(mLinkUp? NETWORK_SCORE : 0);
}
}
这里以NetworkInfo的更新为例:
/**
* Called by the bearer code when it has new NetworkInfo data.
*/
public void sendNetworkInfo(NetworkInfo networkInfo) {
queueOrSendMessage(EVENT_NETWORK_INFO_CHANGED, new NetworkInfo(networkInfo));
}
private void queueOrSendMessage(int what, Object obj) {
synchronized (mPreConnectedQueue) {
if (mAsyncChannel != null) {
mAsyncChannel.sendMessage(what, obj);//mDstMessenger指向CS中的NetworkStateTrackerHandler,mSrcMessenger指向当前NetworkAgent.
} else {
Message msg = Message.obtain();
msg.what = what;
msg.obj = obj;
mPreConnectedQueue.add(msg);
}
}
}
通过已经建立的AsyncChannel连接向ConnectifyService发送消息,并附带需要更新的NetworkInfo对象,这样CS中NetworkStateTrackerHandler就可以收到消息,并进行网络状态更新了。