West2_4 头像上传的实现: https://blog.csdn.net/csdnzouqi/article/details/82256105 https://github.com/Carbs0126/AvatarImageView https://blog.csdn.net/shving/article/details/101057082 自定义View时自定义使用的属性 https://www.jianshu.com/p/8844de6addb3 Retrofit 使用参考 https://stackoverflow.com/questions/47997594/expected-a-string-but-was-begin-array-gson http://www.kotlincodes.com/kotlin/retrofit-with-kotlin/ 关于文件File https://www.coder.work/article/6288575 https://www.jb51.net/article/107273.htm RecyclerView 多选 https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onBindViewHolder(VH,%20int,%20java.util.List%3Cjava.lang.Object%3E) 下载功能参考 https://blog.csdn.net/lkx94/article/details/52918900