【开发方案】Android 双卡设备手动搜网功能适配

一、背景

存在运营商需求：当SIM卡设置中选择了自动搜网，那么在重启开机后要执行一次手动搜网。

若基于本身单卡的实现，只搜索卡槽0的，而且写成了单线程，那么就在适配双卡的过程中还需要调整设计模式。

二、源码逻辑

1. Settings应用发送消息，Telephony 模块Handler回调方法
2. TeleService 处理消息 EVENT_GET_NETWORK_SELECTION_MODE_DONE，并notifyRequester()
3. TelephonyManager => MD

（一）Settings APP

packages/apps/Settings/src/com/android/settings/network/  界面

（二）Telephony Service

packages/services/Telephony/src/com/android/phone/PhoneInterfaceManager.java 业务逻辑

• handleMessage -> notifyRequester

    /**
     * A handler that processes messages on the main thread in the phone process. Since many
     * of the Phone calls are not thread safe this is needed to shuttle the requests from the
     * inbound binder threads to the main thread in the phone process.  The Binder thread
     * may provide a {@link MainThreadRequest} object in the msg.obj field that they are waiting
     * on, which will be notified when the operation completes and will contain the result of the
     * request.
     *
     * 
If a MainThreadRequest object is provided in the msg.obj field,
     * note that request.result must be set to something non-null for the calling thread to
     * unblock.
     */
    private final class MainThreadHandler extends Handler {
        @Override
        public void handleMessage(Message msg) {
            MainThreadRequest request;  
            Message onCompleted;
            AsyncResult ar;
            UiccPort uiccPort;
            IccAPDUArgument iccArgument;
            final Phone defaultPhone = getDefaultPhone();
    
            switch (msg.what) {
                case EVENT_GET_NETWORK_SELECTION_MODE_DONE:
                    //obj参数保存了一个AsyncResult对象
                    ar = (AsyncResult) msg.obj;
                    //userObj参数保存了一个MainThreadRequest对象
                    request = (MainThreadRequest) ar.userObj;
                    if (ar.exception != null) {  //异步请求异常，设置结果unknown
                        request.result = TelephonyManager.NETWORK_SELECTION_MODE_UNKNOWN;
                    } else {  //根据异步请求结果设置网络选择模式
                        int mode = ((int[]) ar.result)[0];
                        if (mode == 0) {  //mode0自动搜网
                            request.result = TelephonyManager.NETWORK_SELECTION_MODE_AUTO;
                        } else {  //mode1手动搜网
                            request.result = TelephonyManager.NETWORK_SELECTION_MODE_MANUAL;
                        }
                    }
                    notifyRequester(request);  //通知请求异步操作的结果
                    break;
                default:
                    Lo