如何导入RecyclerView

我的build.gradle中没有dependens 如下：（如何添加compile android.support.v7-recyclerView）
// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
repositories {
jcenter()
}
dependencies {
classpath 'com.android.tools.build:gradle:2.2.0'

// NOTE: Do not place your application dependencies here; they belong
// in the individual module build.gradle files
}
}

allprojects {
repositories {
jcenter()
}
}

task clean(type: Delete) {
delete rootProject.buildDir
}