android区域连接，Internet连接和云连接

android在网络方面提供下面的功能：提供无线连接网络的方式，使用网络发现服务和Wi-Fi创建点到点的连接。使用XML格式来交换网络数据。在下载和网络交换中，如何减少电池的消耗。

在云方面，可以同步和备份用户数据。

下面是具体内容：

1.网络服务发现允许你的用户发现和识别本地网络的其他设备，这在文件共享和多个玩家的游戏中非常实用。android的NSD API简单的提供了这样的功能。下面讲述如何广播自己的用户名和连接信息，同时可以扫描其他的设备。

public void registerService(int port) {
// Create the NsdServiceInfo object, and populate it.
NsdServiceInfo serviceInfo = new NsdServiceInfo();

    // The name is subject to change based on conflicts
    // with other services advertised on the same network.
    serviceInfo.setServiceName("NsdChat");
    serviceInfo.setServiceType("_http._tcp.");
    serviceInfo.setPort(port);
    ....
}

public void initializeServerSocket() {
// Initialize a server socket on the next available port.
mServerSocket = new ServerSocket(0);

    // Store the chosen port.
    mLocalPort = mServerSocket.getLocalPort();
    ...
}

public void initializeRegistrationListener() {
mRegistrationListener = new NsdManager.RegistrationListener() {

        @Override
        public void onServiceRegistered(NsdServiceInfo NsdServiceInfo) {
            // Save the service name. Android may have changed it in order to
            // resolve a conflict, so update the name you initially requested
            // with the name Android actually used.
            mServiceName = NsdServiceInfo.getServiceName();
        }

        @Override
        public void onRegistrationFailed(NsdServiceInfo serviceInfo, int errorCode) {
            // Registration failed! Put debugging code here to determine why.
        }

        @Override
        public void onServiceUnregistered(NsdServiceInfo arg0) {
            // Service has been unregistered. This only happens when you call
            // NsdManager.unregisterService() and pass in this listener.
        }

        @Override
        public void onUnregistrationFailed(NsdServiceInfo serviceInfo, int errorCode) {
            // Unregistration failed. Put debugging code here to determine why.
        }
    };
}

public void registerService(int port) {
    NsdServiceInfo serviceInfo = new NsdServiceInfo();
    serviceInfo.setServiceName("NsdChat");
    serviceInfo.setServiceType("_http._tcp.");
    serviceInfo.setPort(port);

mNsdManager = Context.getSystemService(Context.NSD_SERVICE);

mNsdManager.registerService(
serviceInfo, NsdManager.PROTOCOL_DNS_SD, mRegistrationListener);
}

上面是注册的代码。下面是发现网络的代码：

public void initializeDiscoveryListener() {

// Instantiate a new DiscoveryListener
mDiscoveryListener = new NsdManager.DiscoveryListener() {

        // Called as soon as service discovery begins.
        @Override
        public void onDiscoveryStarted(String regType) {
            Log.d(TAG, "Service discovery started");
        }

        @Override
        public void onServiceFound(NsdServiceInfo service) {
            // A service was found! Do something with it.
            Log.d(TAG, "Service discovery success" + service);
            if (!service.getServiceType().equals(SERVICE_TYPE)) {
                // Service type is the string containing the protocol and
                // transport layer for this service.
                Log.d(TAG, "Unknown Service Type: " + service.getServiceType());
            } else if (service.getServiceName().equals(mServiceName)) {
                // The name of the service tells the user what they'd be
                // connecting to. It could be "Bob's Chat App".
                Log.d(TAG, "Same machine: " + mServiceName);
            } else if (service.getServiceName().contains("NsdChat")){
                mNsdManager.resolveService(service, mResolveListener);
            }
        }

        @Override
        public void onServiceLost(NsdServiceInfo service) {
            // When the network service is no longer available.
            // Internal bookkeeping code goes here.
            Log.e(TAG, "service lost" + service);
        }

        @Override
        public void onDiscoveryStopped(String serviceType) {
            Log.i(TAG, "Discovery stopped: " + serviceType);
        }

@Override
public void onStartDiscoveryFailed(String serv

补充：移动开发 , Android ,