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Android 4.4 Kitkat 使能有线网络 Ethernet
背景
Android kitkat 默认已经支持 Ethernet 有线网络,只要稍微配置,便可以直接使用,测试结果,网络浏览器和下载都没有没有问题,而且系统可以做到与 wifi 共存,互相不影响功能,这里简单介绍如何使能 Ethernet,并简要分析其代码和流程。
Linux 配置部分
Linux 需要能够支持有线网络,生成 eth 网络设备节点。
Android 配置
overlay
主要是 overlay 里面添加 Ethernet 网络类型支持: frameworks/base/core/res/res/values/config.xml
<string-array translatable="false" name="radioAttributes"> <item>"1,1"</item> <item>"7,1"</item> <item>"9,1"</item> </string-array>
其中 9 对应 Ethernet 的网络类型,其定义在 ConnectivityManager.java 中
/** * The Ethernet data connection. When active, all data traffic * will use this network type's interface by default * (it has a default route). */ public static final int TYPE_ETHERNET = 9;
init.<board>.rc
init 里面需要添加 dhcp 和 ip renew 服务
# DHCPCD # # eth0 service dhcpcd_eth0 /system/bin/dhcpcd -ABKL class main disabled oneshot # IP Renew # # eth0 service iprenew_eth0 /system/bin/dhcpcd -n class main disabled oneshot
流程分析
ConnectivityService
ConnectivityService 的构造函数里面将会读取 radioAttributes 里面的网络配置
public ConnectivityService(Context context, INetworkManagementService netManager, INetworkStatsService statsService, INetworkPolicyManager policyManager, NetworkFactory netFactory) { if (DBG) log("ConnectivityService starting up");
// Load device network attributes from resources String[] raStrings = context.getResources().getStringArray( com.android.internal.R.array.radioAttributes); for (String raString : raStrings) { RadioAttributes r = new RadioAttributes(raString); if (VDBG) log("raString=" + raString + " r=" + r); if (r.mType > ConnectivityManager.MAX_RADIO_TYPE) { loge("Error in radioAttributes - ignoring attempt to define type " + r.mType); continue; } if (mRadioAttributes[r.mType] != null) { loge("Error in radioAttributes - ignoring attempt to redefine type " + r.mType); continue; } mRadioAttributes[r.mType] = r; }
根据网络配置数据,将会创建 EthernetDataTracker , 并开始监听 startMonitoring
// Create and start trackers for hard-coded networks for (int targetNetworkType : mPriorityList) { final NetworkConfig config = mNetConfigs[targetNetworkType]; final NetworkStateTracker tracker; try { tracker = netFactory.createTracker(targetNetworkType, config); mNetTrackers[targetNetworkType] = tracker; } catch (IllegalArgumentException e) { Slog.e(TAG, "Problem creating " + getNetworkTypeName(targetNetworkType) + " tracker: " + e); continue; } tracker.startMonitoring(context, mTrackerHandler); if (config.isDefault()) { tracker.reconnect(); } }
EthernetDataTracker
<!-- Regex of wired ethernet ifaces --> <string translatable="false" name="config_ethernet_iface_regex">eth\\d</string>
sIfaceMatch = context.getResources().getString( com.android.internal.R.string.config_ethernet_iface_regex); try { final String[] ifaces = mNMService.listInterfaces(); for (String iface : ifaces) { if (iface.matches(sIfaceMatch)) { mNMService.setInterfaceUp(iface); InterfaceConfiguration config = mNMService.getInterfaceConfig(iface); if (getEthernetCarrierState(iface) == 1) { mIface = iface; mLinkUp = true; mNetworkInfo.setIsAvailable(true); if (config != null && mHwAddr == null) { mHwAddr = config.getHardwareAddress(); if (mHwAddr != null) { mNetworkInfo.setExtraInfo(mHwAddr); } } } // if a DHCP client had previously been started for this interface, then stop it NetworkUtils.stopDhcp(iface); } } reconnect(); } catch (RemoteException e) { Log.e(TAG, "Could not get list of interfaces " + e); }
mNetworkInfo.setDetailedState(DetailedState.CONNECTED, null, mHwAddr); Message msg = mCsHandler.obtainMessage(EVENT_STATE_CHANGED, mNetworkInfo); msg.sendToTarget();
如果有多个网口呢,这个 EthernetDataTracker 显然不能满足要求,必须对其进行扩展。
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