USB 拔插广播
在开发中发现USB 在连接情况下，app 侦测 断开，因此需要添加log,查看系统是否有广播

目前 先使用host manager run 监控方式
1- 设备插入： 广播ACTION_USB_DEVICE_ATTACHED
2- 设备拔出： 广播ACTION_USB_DEVICE_DETACHED
/frameworks/base/core/java/android/hardware/usb/UsbManager.java

public static final String ACTION_USB_DEVICE_ATTACHED = "android.hardware.usb.action.USB_DEVICE_ATTACHED";
public static final String ACTION_USB_DEVICE_DETACHED = "android.hardware.usb.action.USB_DEVICE_DETACHED";

frameworks/base/services/usb/java/com/android/server/usb/UsbHostManager.java
流程:

UsbHostManager 启动监控线程
    ---》注册了endUsbDeviceAdded，usbDeviceRemoved 函数
         ---》 监控USB 插入后，调用endUsbDeviceAdded （拔出：usbDeviceRemoved）
             ---》 发送ACTION_USB_DEVICE_ATTACHED 广播 （拔出：ACTION_USB_DEVICE_DETACHED）

图片.png

UsbHostManager 启动监控线程：

systemReady -> UsbHostManager.java
  monitorUsbHostBus ->
   android_server_UsbHostManager_monitorUsbHostBus -> android_server_UsbHostManager.cpp
    usb_host_run -> Usbhost.c
      usb_host_read_event ->
        context->cb_added -> //有usb设备添加, 删除是cb_removed， 都是UsbHostManager 注册下来的
        　　usb_device_added ->
            env->CallVoidMethod -> //对方方法method_endUsbDeviceAdded　 --> endUsbDeviceAdded
              endUsbDeviceAdded -> UsbHostManager.java

最后走到了：UsbHostManager :endUsbDeviceAdded

endUsbDeviceAdded -->
    deviceAttached-->UsbProfileGroupSettingsManager
         mContext.sendBroadcastAsUser-->发送ACTION_USB_DEVICE_ATTACHED

UsbHostManager.java: usbDeviceRemoved:

    /* Called from JNI in monitorUsbHostBus to report USB device removal */
    @SuppressWarnings("unused")
    private void usbDeviceRemoved(String deviceName) {
        synchronized (mLock) {
            UsbDevice device = mDevices.remove(deviceName);
            if (device != null) {
                Slog.d(TAG, "usbDeviceRemoved:"+device.getProductName());
                mUsbAlsaManager.usbDeviceRemoved(device);
                mSettingsManager.usbDeviceRemoved(device);//-->发送ACTION_USB_DEVICE_DETACHED
                getCurrentUserSettings().usbDeviceRemoved(device);
            }
        }
    }

备注:UsbHostManager:systemReady 什么时候被调用
调用流程：

SystemServer （SystemServer.java）
    --->UsbService （SystemServer.java）
       --->startBootPhase （SystemServer.java）
           --->startBootPhase  (UsbService.java)
             --->UsbHostManager :systemReady （UsbHostManager.java）

frameworks/base/services/java/com/android/server/SystemServer.java

private static final String USB_SERVICE_CLASS = "com.android.server.usb.UsbService$Lifecycle";

startOtherServices
    -->startService(USB_SERVICE_CLASS);--->启动UsbService
        --> startBootPhase(SystemService.PHASE_SYSTEM_SERVICES_READY);
             -->service.onBootPhase(mCurrentPhase); --》启动所有service **onBootPhase** 函数

SystemServer.java：startBootPhase:

 public void startBootPhase(final int phase) {
        if (phase <= mCurrentPhase) {
            throw new IllegalArgumentException("Next phase must be larger than previous");
        }
        mCurrentPhase = phase;

        Slog.i(TAG, "Starting phase " + mCurrentPhase);
        try {
            Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "OnBootPhase " + phase);
            final int serviceLen = mServices.size();
            for (int i = 0; i < serviceLen; i++) {
                final SystemService service = mServices.get(i);
                long time = SystemClock.elapsedRealtime();
                Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, service.getClass().getName());
                try {
                    service.onBootPhase(mCurrentPhase);
                } catch (Exception ex) {
                    throw new RuntimeException("Failed to boot service "
                            + service.getClass().getName()
                            + ": onBootPhase threw an exception during phase "
                            + mCurrentPhase, ex);
                }
                warnIfTooLong(SystemClock.elapsedRealtime() - time, service, "onBootPhase");
                Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER);
            }
        } finally {
            Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER);
        }
    }

frameworks/base/services/usb/java/com/android/server/usb/UsbService.java

UsbService.java:onBootPhase
    -->mUsbService.systemReady();
        -->mHostManager.systemReady();

UsbService.java：onBootPhase：

        @Override
        public void onBootPhase(int phase) {
            if (phase == SystemService.PHASE_ACTIVITY_MANAGER_READY) {
                mUsbService.systemReady();
            } else if (phase == SystemService.PHASE_BOOT_COMPLETED) {
                mUsbService.bootCompleted();
            }
        }

UsbService.java:systemReady：

    public void systemReady() {
        mAlsaManager.systemReady();

        if (mDeviceManager != null) {
            mDeviceManager.systemReady();
        }
        if (mHostManager != null) {
            mHostManager.systemReady();
        }
        if (mPortManager != null) {
            mPortManager.systemReady();
        }
    }