需求

项目中Android 板通过有线连接poe摄像头， android app通过wifi跟外部通讯。采用的Android 8.1的代码。

网上搜索发现有不少实现该功能的文章，不过文章都有一些差异，对于不了解这些模块的人来说会不知道应该修改哪个。这里只简单记录下我的调试记录，还没深究

现象

这边照着网上几篇文章修改后，出现的现象是：eth0 处于Running的状态时， 去重连wifi， wifi只会显示saved，不会继续走configure流程

调试

最常见的的方法就是通过打印去了解信息，把涉及到NetworkFactory 和ConnectivityService的打印都打开 没有连接eth0时点击wifi连接的打印 09-03 01:59:40.998 465 561 D WifiStateMachine: connectToUserSelectNetwork netId 3, uid 1000, forceReconnect = false 09-03 01:59:41.033 465 561 D WifiStateMachine: CMD_START_CONNECT sup state DisconnectedState my state DisconnectedState nid=3 roam=false 09-03 01:59:43.300 465 561 D WifiStateMachine: CMD_START_CONNECT sup state ScanState my state DisconnectedState nid=3 roam=false 09-03 01:59:45.650 465 561 E WifiStateMachine: L2ConnectedState enter eth0处于running时，点击wifi连接的打印 09-03 02:02:47.526 465 561 D WifiStateMachine: connectToUserSelectNetwork netId 4, uid 1000, forceReconnect = false 09-03 02:02:47.564 465 561 E WifiStateMachine: CMD_START_CONNECT but no requests and not connected, bailing

由打印的差异 跟踪到代码 frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiStateMachine.java

case CMD_START_CONNECT: /* connect command coming from auto-join */ netId = message.arg1; int uid = message.arg2; bssid = (String) message.obj; synchronized (mWifiReqCountLock) { if (!hasConnectionRequests()) { loge("hasConnectionRequests :......"); if (mNetworkAgent == null) { loge("CMD_START_CONNECT but no requests and not connected," + " bailing"); break; } else if (!mWifiPermissionsUtil.checkNetworkSettingsPermission(uid)) { loge("CMD_START_CONNECT but no requests and connected, but app " + "does not have sufficient permissions, bailing"); break; } } } config = mWifiConfigManager.getConfiguredNetworkWithPassword(netId); logd("CMD_START_CONNECT sup state " + mSupplicantStateTracker.getSupplicantStateName() + " my state " + getCurrentState().getName() + " nid=" + Integer.toString(netId) + " roam=" + Boolean.toString(mIsAutoRoaming)); if (config == null) { loge("CMD_START_CONNECT and no config, bail out..."); break; } private boolean hasConnectionRequests() { return mConnectionReqCount > 0 || mUntrustedReqCount > 0; }

从打印和代码分析，两个流程的差异主要在hasConnectionRequests这个函数

接下来主要跟踪hasConnectionRequests 从代码查到主要问题在mConnectionReqCount这个变量，所以查找修改这个变量的地方，还好只有两处： @Override protected void needNetworkFor(NetworkRequest networkRequest, int score) { synchronized (mWifiReqCountLock) { loge("needNetworkFor mConnectionReqCount="+ mConnectionReqCount); if (++mConnectionReqCount == 1) { if (mWifiConnectivityManager != null && mUntrustedReqCount == 0) { mWifiConnectivityManager.enable(true); } } } } @Override protected void releaseNetworkFor(NetworkRequest networkRequest) { synchronized (mWifiReqCountLock) { loge("releaseNetworkFor mConnectionReqCount="+ mConnectionReqCount); Exception e = new Exception("log"); e.fillInStackTrace(); loge("Called: " , e); if (--mConnectionReqCount == 0) { if (mWifiConnectivityManager != null && mUntrustedReqCount == 0) { mWifiConnectivityManager.enable(false); } } } }

为了能知道对这个变量的调用流程，一个简单的方法就是利用Exception打印出堆栈信息 Exception e = new Exception(“log”); e.fillInStackTrace(); loge("Called: " , e);

堆栈打印信息忘记记下来了，这里只记下最后修改的地方 frameworks/base/core/java/android/net/NetworkFactory.java private void evalRequest(NetworkRequestInfo n) { if (VDBG) log("evalRequest"); Log.e("NetworkFactory", "evalRequest n.score:" + n.score + ", mScore:" + mScore); 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"); } }

将下面两行注释掉 //releaseNetworkFor(n.request); //n.requested = false;

最终修改的地方有3处：

写一个启动脚本，在系统启动时配置eth0, ip地址与wifi不在同一个网断 ip route add 192.168.11.0/24 dev eth0 proto static table local_network ip route flush cache sleep 5s ifconfig eth0 192.168.11.120 修改frameworks/opt/net/ethernet/java/com/android/server/ethernet/EthernetNetworkFactory.java private static final int NETWORK_SCORE = 30; //70; 修改frameworks/base/core/java/android/net/NetworkFactory.java 注释掉 //releaseNetworkFor(n.request); //n.requested = false;