简单，小巧，可靠，灵活的Android下载引擎! Simple,Small, Reliable And Flexible Android download engine
1、支持任意时刻动态调整下载任务的优先级，方便用户手动调整下载顺序
2、只关心核心的线程调度，数据保存可以自由定制
3、网络下载模块也可以非常方便的定制，便于和现在流行的网络库okhttp，防劫持的库httpdns等结合
4、该库里面所有的线程一旦空闲超时都会自动销毁，释放资源
5、稳定性有保障，有线上应用正在使用:)
Copyright (C) 2018 yueyueniao
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.