android4.4 重启的开机不播放开机铃声，按power键的开机播放开机铃声

平台:A33
Android4.4
Linux3.4

功能描述:实现重启的开机不播放开机铃声，按power键的开机播放开机铃声

一，无论关机还是重启都会经过rebootOrShutdown这个方法，在方法中通过参数reboot判断是否为重启，否则直接关机。在重启的那部分代码中新建一个文件/data/for_reboot_check.txt并写入"reboot"信息。注:文件创建在/sdcard目录中不合适，因为/sdcard目录是启动后期挂载的，在/system/目录中创建文件没有权限，所以选择在/data/目录中创建
代码路径：android/frameworks/base/services/java/com/android/server/power/ShutdownThread.java

/**
     * Do not call this directly. Use {@link #reboot(Context, String, boolean)}
     * or {@link #shutdown(Context, boolean)} instead.
     *
     * @param reboot true to reboot or false to shutdown
     * @param reason reason for reboot
     */
    public static void rebootOrShutdown(boolean reboot, String reason) {
        if (reboot) {    //if is reboot create a new file

            //add by jin,create a new file to store shutdown information
            //=======================================================
            String filenameTemp;
            String path;
            FileWriter writer = null;

            filenameTemp = "/data"+"/for_reboot_check" + ".txt";    //file path
            File filename = new File(filenameTemp);    

            Log.i(TAG, "----new file-----");
            try{
                if(!filename.exists()){
                     filename.createNewFile();     //create a new file
                     Log.i(TAG, "------create new file:"+ filenameTemp+"-----\n");
                }
                writer = new FileWriter(filename, false);
                writer.append("reboot");                         //write data to file
                Log.i(TAG, "------writer data-----\n");
                writer.flush();            //flush write cache

                Log.i(TAG, "flush");
                        writer.close();      //close writer
            }catch(IOException e){
                e.printStackTrace();
            }finally{
                if(null != writer){
                }
            }
            //================================================================================

            Log.i(TAG, "Rebooting, reason: " + reason);
            try {
                PowerManagerService.lowLevelReboot(reason);
            } catch (Exception e) {
                Log.e(TAG, "Reboot failed, will attempt shutdown instead", e);
            }
        } else if (SHUTDOWN_VIBRATE_MS > ) {
            // vibrate before shutting down
            Vibrator vibrator = new SystemVibrator();
            try {
                vibrator.vibrate(SHUTDOWN_VIBRATE_MS);
            } catch (Exception e) {
                // Failure to vibrate shouldn't interrupt shutdown.  Just log it.
                Log.w(TAG, "Failed to vibrate during shutdown.", e);
            }

            // vibrator is asynchronous so we need to wait to avoid shutting down too soon.
            try {
                Thread.sleep(SHUTDOWN_VIBRATE_MS);
            } catch (InterruptedException unused) {
            }
        }
                IWindowManager  mWindowManager;
                mWindowManager = IWindowManager.Stub.asInterface(ServiceManager.getService("window"));
                if(mWindowManager != null ){
                        try{
                                if(isFreeze==){
                                        mWindowManager.thawRotation();
                                        mWindowManager.updateRotation(true, true);
                                        mWindowManager.setEventDispatching(false);
                                }

            }catch (RemoteException e) {
            }
                }
        // Shutdown power
        Log.i(TAG, "Performing low-level shutdown...");
        PowerManagerService.lowLevelShutdown();
    }

二，开机动画和开机铃声是由bootanimation应用实现的，在开机动画播放前读取/data/for_reboot_check.txt文件的内容，判断上次关机是否是重启，如果是重启则不播放开机铃声，

代码路径：android/frameworks/base/cmds/bootanimation/bootanimation_main.cpp

int main(int argc, char** argv)
{
#if 1
        //add by jin, for check reboot information
        //=======================================================
        FILE *file = NULL;
        int ret = ;
        int flag = ;  //用于判断是否是重启
        char buf_read[];

        file = fopen("/data/for_reboot_check.txt", "rt+");
        if(file == NULL){
                printf("------file open failed----\n");
                //return -1;
        }else{
                printf("------file open sucess----\n");
                ret = fread(buf_read, sizeof(char), , file);
                if(ret != )
                {
                        printf("----read failed:ret=%d----\n",ret);
                }else{

                        printf("-----%s----\n", buf_read);
                        if(strncmp("reboot", buf_read, sizeof("reboot")) == ){
                                printf("------cmp sucess----\n");
                                flag = ;  //为重启，则flag置1

                                if(remove("/data/for_reboot_check.txt") ==)
                                        printf("----remove file sucess----");

                        }else{
                                //return -1;
                        }
                }
        }

#endif
    //===============================================================
#if defined(HAVE_PTHREADS)
    setpriority(PRIO_PROCESS, , ANDROID_PRIORITY_DISPLAY);
#endif

    char value[PROPERTY_VALUE_MAX];
    property_get("debug.sf.nobootanimation", value, "");
    int noBootAnimation = atoi(value);
    ALOGI_IF(noBootAnimation,  "boot animation disabled");
    if (!noBootAnimation) {
        char cmd[PROPERTY_VALUE_MAX];
        property_get("sys.shutdown_animation", cmd, "boot");
        const char* url = "/system/media/boot.wav";
        if (!strcmp(cmd, "shutdown")) {
            url = "/system/media/shutdown.wav";
        }

        sp<ProcessState> proc(ProcessState::self());
        ProcessState::self()->startThreadPool();

        // create the boot animation object
        sp<BootAnimation> boot = new BootAnimation();

        //add by jin, flag为0，则为关机后的启动，flag为1，则为重启后的启动
        if(flag == ){
                boot->playBootMusic(url);
        }

        IPCThreadState::self()->joinThreadPool();

    }
    return ;
}

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关于关机重启的流程分析：https://blog.csdn.net/lxl584685501/article/details/45747967