<shape xmlns:android="http://schemas.android.com/apk/res/android" >

    <!--这里是Linearlayout布局的背景颜色-->

    <solid android:color="@color/white" />

    <!--这里是设置边框线的粗细和颜色-->

    <stroke

        android:width="2dp"

        android:color="@color/el_warning" />

    <padding

        android:bottom="1dp"

        android:left="1dp"

        android:right="1dp"

        android:top="1dp" />

    <!--角的话，里边有参数可以单独设置-->

    <corners android:radius="20dp" />

</shape>

设置左侧的icon 这里设置为不显示左侧icon  api22 以下无效果

android:searchIcon="@null"    

下面这两项处理不显示下划线   api21 以下无效果

android:queryBackground="@null"

android:submitBackground="@null"

app:searchIcon="@null"

app:queryBackground="@null"

app:submitBackground="@null"

search_view.requestFocus()

        search_view.setOnQueryTextListener(object : SearchView.OnQueryTextListener {

            override fun onQueryTextChange(newText: String?): Boolean {

                Log.d(tag,"textChange=$newText")

                return false

            }

            override fun onQueryTextSubmit(query: String?): Boolean {

                Log.d(tag,"textSubmit=$query")

                if(query.isNullOrBlank()){

                    Toast.makeText(this@CourseSearch,"请输入搜索条件",Toast.LENGTH_SHORT).show()

                    return false

                }

                if(query.length < 2 || query.length > 20){

                    Toast.makeText(this@CourseSearch,"搜索条件2-20位字符",Toast.LENGTH_SHORT).show()

                    return false

                }

                //查询处理代码

                return false

            }

        })