Android Studio com.google.android.exoplayer2不存在错误

我从GitHub下载了一个应用程序源代码，当我在android studio上打开该项目时，它显示错误，并且（无法在Android Studio中编译exoplayer）我也阅读并尝试了此StackOverflow答案，但未能解决我的问题

error: package com.google.android.exoplayer2 does not exist

并建立输出错误

build.gradle（模块：应用）代码

    apply plugin: 'com.android.application'

    android {
    compileSdkVersion 28
    defaultConfig {
    applicationId "tabian.com.app"
    minSdkVersion 15
    targetSdkVersion 28
    versionCode 1
    versionName "1.0"
    testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
}
    }

    dependencies {
implementation fileTree(include: ['*.jar'], dir: 'libs')
androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
    exclude group: 'com.android.support', module: 'support-annotations'
})
implementation 'com.android.support:appcompat-v7:28.0.0'
implementation 'com.android.support.constraint:constraint-layout:1.0.2'
testImplementation 'junit:junit:4.12'
//Design library for Coordinator Layout and Toolbars
implementation 'com.android.support:design:28.0.0'
//ExifInterface support
implementation 'com.android.support:exifinterface:28.0.0'
//design library for Coordinator Layout
implementation 'com.android.support:design:28.0.0'
//Exo Player
implementation 'com.google.android.exoplayer:exoplayer:r1.5.2'
//cardview
implementation 'com.android.support:cardview-v7:28.0.0'
//recyclerview
implementation 'com.android.support:recyclerview-v7:28.0.0'
//BottomNavigationViewEx library
implementation 'com.github.ittianyu:BottomNavigationViewEx:1.1.9'
//Circle ImageView
implementation 'de.hdodenhof:circleimageview:2.1.0'
//elastic header
implementation 'com.github.eschao:android-ElasticListView:v1.0'
//material dialogs
implementation 'com.afollestad.material-dialogs:core:0.9.6.0'
//glide
implementation 'com.github.bumptech.glide:glide:4.4.0'
annotationProcessor 'com.github.bumptech.glide:compiler:4.4.0'
implementation files('libs/aspectjrt-1.7.3 (1).jar')
//Universal image loader
implementation 'com.nostra13.universalimageloader:universal-image-loader:1.9.5'
//firebase authentication
implementation 'com.google.firebase:firebase-auth:10.2.6'
//firebase database
implementation 'com.google.firebase:firebase-database:10.2.6'
//firebase storage
implementation 'com.google.firebase:firebase-storage:10.2.6'
implementation files('libs/aspectjrt-1.7.3 (1).jar')
   }

    //Firebase
    apply plugin: 'com.google.gms.google-services'