1. 总的布局文件

<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.gx.gxzx.ui.realtime.commonElec.CommonElecActivity">
    <android.support.design.widget.AppBarLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        xmlns:app="http://schemas.android.com/apk/res-auto">
        <android.support.design.widget.CollapsingToolbarLayout
            android:layout_width="match_parent"
            app:layout_scrollFlags="scroll|enterAlways|snap"
            android:layout_height="wrap_content">
            <android.support.v7.widget.Toolbar
                android:id="@+id/my_toolbar"
                android:paddingTop="20dp"
                app:contentInsetStart="0dp"
                android:layout_width="match_parent"
                android:layout_height="wrap_content">
                <RelativeLayout
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content">
                    <android.support.v7.widget.AppCompatImageButton
                        android:id="@+id/my_toolbar_back"
                        android:src="@drawable/ic_back_white"
                        android:background="?controlBackground"
                        android:layout_margin="10dp"
                        android:layout_centerVertical="true"
                        android:layout_width="25dp"
                        android:layout_height="25dp" />
                    <ImageView
                        android:id="@+id/my_toolbar_loading"
                        android:layout_centerVertical="true"
                        android:layout_toLeftOf="@+id/my_toolbar_title"
                        android:layout_width="25dp"
                        android:layout_marginRight="10dp"
                        android:layout_height="25dp" />
                    <TextView
                        android:id="@+id/my_toolbar_title"
                        android:text="tltie"
                        android:textColor="@color/white"
                        android:textSize="@dimen/title"
                        android:gravity="center"
                        android:layout_centerInParent="true"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content" />
                </RelativeLayout>
            </android.support.v7.widget.Toolbar>
        </android.support.design.widget.CollapsingToolbarLayout>
        <com.gx.gxzx.widget.MyDeviceSelector
            android:id="@+id/my_device_selector"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>
    </android.support.design.widget.AppBarLayout>
        <android.support.v4.widget.SwipeRefreshLayout
        android:id="@+id/swipe_refresh_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior">
        <android.support.v4.widget.NestedScrollView
            android:layout_width="match_parent"
            android:layout_weight="1"
            android:layout_height="0dp">
            ....
            </android.support.v4.widget.NestedScrollView>
    </android.support.v4.widget.SwipeRefreshLayout>


</android.support.design.widget.CoordinatorLayout>

#2. 要点 ##2.1 app:contentInsetStart="0dp"

会使toolbar里面的View会扩充到左右，不会有间隙。