object FileDownloadConstant {
const val filePath = “gifts/zip”
//下载下来的资源存放的根目录
var DEFAULT_FILE_CACHE_PATH = ContextUtils.getApplicationContext().getExternalFilesDir(“gift”).path
//礼物动画存储目录
var rootPathAnimation = “ D E F A U L T F I L E C A C H E P A T H / {DEFAULT_FILE_CACHE_PATH}/ DEFAULTF​ILEC​ACHEP​ATH/{filePath}”

object BaseConfig{
//资源存放的apk地址
const val ANIMATION_OSS_URL = “https://static.network.com”
const val GIFT_PATH = “ A N I M A T I O N O S S U R L / {ANIMATION_OSS_URL}/ ANIMATIONO​SSU​RL/{filePath}”
}

//资源列表
var giftList = listOf(“xiagujian”,“chiji”,“kele”,“banzhuan”,“memeda”,“qiujiaowang”,“qiqiu”,“penghua”,
“yanhua”,“meigui”,“feiji”,“chengbao”,“bixin”,“loveyou”,“sobuteful”,“hongchun”,“girlfri”,“huangguan”,
“leihen”,“qiubite”,“haozhuchi”,“zhuguang”,“langman”,“bidong”,“dangao”,“laohu”,“mao”,“xiong”,“hunsha”,
“dianzan”,“bangbangtang”,“icecream”,“yiwendingqing”,“haidao”,“iphone”,“yecanyuehui”,“lovetree”,“jiarilvxing”)
}

文件下载工具类

/**

• 文件下载工具类
  */
  object FileDownloadUtil {
  private val parentPath = FileDownloadConstant.rootPathAnimation
  private val fetch = Fetch.getInstance(FetchConfiguration.Builder(ContextUtils.getApplicationContext())
  .setLogger(FetchLogger(true,“动画下载”))
  .enableLogging(true)
  .setDownloadConcurrentLimit(5)
  .setAutoRetryMaxAttempts(3)
  .setHttpDownloader(OkHttpDownloader(Downloader.FileDownloaderType.PARALLEL))
  .setProgressReportingInterval(1000)
  .build())

/**

• 下载监听
  */
  class DownloadListener(private val groupId : Int,private val num:Int,private val callback 😦(Boolean) -> Unit) ?) : AbstractFetchListener(){
  private var downloaded: Int = 0 //已下载的数量
  override fun onCompleted(download: Download) {
  if (download.group != groupId) {
  return
  }
  //资源打包成zip文件放到了服务器上，所以下载下来要解压缩
  LottieAnimationUtils.unZip(download.file, parentPath)
  downloadCount(true)
  }

override fun onError(download: Download, error: Error, throwable: Throwable?) {
if (download.group != groupId) {
return
}
downloadCount(false)
}

private val downloadCount: (Boolean) -> Unit = {
downloaded++
if (downloaded == num) {
callback?.invoke(it)
fetch.removeListener(this)
}
}
}

fun downloadList(pathList: List, priority: Priority = Priority.NORMAL, callback: ((Boolean) -> Unit)? = null) {
val groupId = Random.nextInt()
pathList.filter {
//本地文件不存在的才下载
!File(parentPath + File.separator + it).exists()
}.flatMap { path ->
arrayListOf(Request(“ F i l e D o w n l o a d C o n s t a n t . B a s e C o n f i g . G I F T P A T H / {FileDownloadConstant.BaseConfig.GIFT_PATH}/ FileDownloadConstant.BaseConfig.GIFTP​ATH/path” + “.zip”, parentPath + “/” + path + “.zip”).also {
it.groupId = groupId
it.priority = priority
})
}.apply {
if (size == 0) {
callback?.invoke(true)
return@apply
}
fetch.addListener(DownloadListener(groupId, size, callback)).enqueue(this)
}
}

/**

• 下载单个文件
  */
  fun download(path: String, callback: ((Boolean) -> Unit)? = null) {
  if (File(“ p a r e n t P a t h / parentPath/ parentPath/path” + “.zip”).exists()) {
  callback?.invoke(true)
  return
  }
  val groupId = Random.nextInt()
  fetch.addListener(DownloadListener(groupId, 1, callback)).enqueue(Request(“ F i l e D o w n l o a d C o n s t a n t . B a s e C o n f i g . G I F T P A T H / {FileDownloadConstant.BaseConfig.GIFT_PATH}/ FileDownloadConstant.BaseConfig.GIFTP​ATH/path” + “.zip”, “ p a r e n t P a t h / parentPath/ parentPath/path.zip”).also { it.groupId = groupId })
  }
  }

下载框架使用的是一个开源的，名字叫Fetch

在启动页的onCreate方法中，调用：

FileDownloadUtil.INSTANCE.downloadList(FileDownloadConstant.INSTANCE.getGiftList(), Priority.NORMAL,null);

就开始下载资源了

那么怎么使用Lottie框架加载文件夹中的动画资源呢？直接上代码

object LottieAnimationUtils {
//lottie加载本地资源的核心方法
fun loadLottie(lottieAnimationView: LottieAnimationView,imagePath:String,dataPath : String,giftName:String):FileInputStream?{
lottieAnimationView.setCacheComposition(false)
val imageFiles = File(imagePath)
val jsonFile = File(dataPath)
var fis:FileInputStream? = null
//资源中只有json文件的时候走这里
if (!imageFiles.exists()) {
if (jsonFile.exists()) {
fis = FileInputStream(jsonFile)
try {
lottieAnimationView.setImageAssetDelegate(null)
}catch (e : Exception) {

}
LottieComposition.Factory.fromInputStream(fis) {
lottieAnimationView.postDelayed(Runnable {
lottieAnimationView.visibility = View.VISIBLE
},200)
it?.let {
it1 -> lottieAnimationView.setComposition(it1)
}
lottieAnimationView.playAnimation()
}
}else {
FileDownloadUtil.download(giftName)
}
return fis
}
//资源中有imges和json的走这里

结尾

我还总结出了互联网公司Android程序员面试涉及到的绝大部分面试题及答案，并整理做成了文档，以及系统的进阶学习视频资料分享给大家。
（包括Java在Android开发中应用、APP框架知识体系、高级UI、全方位性能调优，NDK开发，音视频技术，人工智能技术，跨平台技术等技术资料），希望能帮助到你面试前的复习，且找到一个好的工作，也节省大家在网上搜索资料的时间来学习。

《Android学习笔记总结+移动架构视频+大厂面试真题+项目实战源码》，点击传送门，即可获取！
搜索资料的时间来学习。**

[外链图片转存中…(img-NGrXGGWu-1714771521859)]
《Android学习笔记总结+移动架构视频+大厂面试真题+项目实战源码》，点击传送门，即可获取！