Android Studio依赖添加----aar

(1) 将aar文件复制、粘贴到app/libs目录中
(2) 修改app下的build.gradle配置文件
AS 3.0之前：

    ...
    dependencies {
        compile fileTree(include: ['*.jar'], dir: 'libs')
        testCompile 'junit:junit:4.12'
        compile 'com.android.support:appcompat-v7:25.0.0'
        compile(name:'pullrefreshlibrary', ext:'aar') //引用第三方库
        ...  
    }  
    repositories {
       flatDir {
          dirs 'libs'
       }
    }

AS 3.0之后：

   ...
    dependencies {
        implementation fileTree(include: ['*.jar'], dir: 'libs')
        testImplementation 'junit:junit:4.12'
        implementation 'com.android.support:appcompat-v7:25.0.0'
        implementation(name:'pullrefreshlibrary', ext:'aar') //引用第三方库
        ...  
    }  
  ...

(3) 同步更新Gradle (Sync now)