Caused by: android.util.AndroidRuntimeException: Calling startActivity() from outside of an Activity context requires the FLAG_ACTIVITY_NEW_TASK flag. Is this really what you want?

Context中有一个startActivity方法，Activity继承自Context，重载了startActivity方法。如果使用Activity的startActivity方法，不会有任何限制，而如果使用Context的startActivity方法的话，就需要开启一个新的task，遇到上面那个异常的，都是因为使用了Context的startActivity方法。解决办法是，加一个flag。

intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

以下为Context源码中的startActivity：

    /**

     * Launch a new activity.  You will not receive any information about when      * the activity exits.      *      * <p>Note that if this method is being called from outside of an      * { android.app.Activity} Context, then the Intent must include      * the { Intent#FLAG_ACTIVITY_NEW_TASK} launch flag.  This is because,     * without being started from an existing Activity, there is no existing     * task in which to place the new activity and thus it needs to be placed     * in its own separate task.      *      * <p>This method throws { ActivityNotFoundException}      * if there was no Activity found to run the given Intent.      *      * @param intent The description of the activity to start.      *      * ActivityNotFoundException      *      * PackageManager#resolveActivity      */     public abstract void startActivity(Intent intent);