## 功能：
- 多线程下载
- 断点续传
- 下载速度限制
- 下载速度追踪
- 在下载时修改
- 下载并行连接数
- 速度限制
- 下载块大小
- 下载块信息，下载持续时间等信息
## 局限性
- API 更改较为频繁，且测试不充分，建议 1.0.0 之后在生产环境中使用
- 缺少单元测试（计划以后添加）
- 依赖 tokio
## cargo futures
一些功能默认没有开启，如需开启，请设置 cargo features
```toml
[features]
# 默认开启 tokio tracing
default = ["tracing"]
# 一些类型作为 async-graphql 输入或者输出对象
async-graphql = ["dep:async-graphql"]
# 全部扩展
all-extensions = ["status-tracker", "speed-limiter", "speed-tracker", "breakpoint-resume", "tracing", "bson-file-archiver"]
# 下载状态追踪
status-tracker = ["tracing"]
# 下载速度追踪
speed-tracker = ["tracing"]
# 下载速度限制
speed-limiter = ["tracing"]
# 断点续传
breakpoint-resume = ["tracing"]
# 断点续传，文件存储器
bson-file-archiver = ["breakpoint-resume", "tracing", "serde", "bson", "url/serde"]
```
## 最少需要添加以下依赖
```toml
http-downloader = { version = "0.1" }
tokio = { version = "1", features = ["rt", "macros"] }
url = { version = "2" }
```
## 终端 UI
使用此库做的一个，简单的终端
UI ：[https://github.com/ycysdf/http-downloader-tui](https://github.com/ycysdf/http-downloader-tui)
## 用例
通过 `HttpDownloaderBuilder` `build` 函数参数去设置需要添加的扩展，需要传入一个元组，元组的成员就是扩展
在下面实例里，我传入了4 个扩展，所以 `build` 函数除了返回 下载器实例以外，还会返回包含4个成员的元组，每个成员对应传入的扩展，
例如 `DownloadSpeedTrackerExtension` 扩展，就对应 `DownloadSpeedTrackerState`
通过`DownloadSpeedTrackerState` 的 `reciver` 成员就可以去监听下载速度，或者通过 `download_speed`函数直接去获取当前下载速度
通过 `prepare_download` 去准备下载（要求 `&mut`），它返回 `Result>, DownloadStartError>`，
这个`Future` 是 `'static` 的，除了`prepare_download`，其他方法都不需要`&mut`，
你可以使用`prepare_download`保存返回的`Future`，然后使用 `Arc` 包裹 `build` 出来的 `donwnloader`，以便在多线程中使用
```rust
use std::num::{NonZeroU8, NonZeroUsize};
use std::path::PathBuf;
use std::time::Duration;
use anyhow::Result;
use tracing::info;
use url::Url;
use http_downloader::{
breakpoint_resume::DownloadBreakpointResumeExtension,
HttpDownloaderBuilder,
speed_tracker::DownloadSpeedTrackerExtension,
status_tracker::DownloadStatusTrackerExtension,
};
use http_downloader::bson_file_archiver::{ArchiveFilePath, BsonFileArchiverBuilder};
use http_downloader::speed_limiter::DownloadSpeedLimiterExtension;
#[tokio::main]
async fn main() -> Result<()> {
{
tracing_subscriber::fmt::init();
}
let save_dir = PathBuf::from("C:/download");
let test_url = Url::parse("https://releases.ubuntu.com/22.04/ubuntu-22.04.2-desktop-amd64.iso")?;
let (mut downloader, (status_state, speed_state, speed_limiter, ..)) =
HttpDownloaderBuilder::new(test_url, save_dir)
.chunk_size(NonZeroUsize::new(1024 * 1024 * 10).unwrap()) // 块大小
.download_connection_count(NonZeroU8::new(3).unwrap())
.build((
// 下载状态追踪扩展
// by cargo feature "status-tracker" enable
DownloadStatusTrackerExtension { log: true },
// 下载速度追踪扩展
// by cargo feature "speed-tracker" enable
DownloadSpeedTrackerExtension { log: true },
// 下载速度限制扩展，
// by cargo feature "speed-limiter" enable
DownloadSpeedLimiterExtension::new(None),
// 断点续传扩展，
// by cargo feature "breakpoint-resume" enable
DownloadBreakpointResumeExtension {
// BsonFileArchiver by cargo feature "bson-file-archiver" enable
download_archiver_builder: BsonFileArchiverBuilder::new(ArchiveFilePath::Suffix("bson".to_string()))
}
));
info!("Prepare download，准备下载");
let download_future = downloader.prepare_download()?;
let _status = status_state.status(); // get download status， 获取状态
let _status_receiver = status_state.status_receiver; //status watcher，状态监听器
let _byte_per_second = speed_state.download_speed(); // get download speed，Byte per second，获取速度，字节每秒
let _speed_receiver = speed_state.receiver; // get download speed watcher，速度监听器
// downloader.cancel() // 取消下载
// 打印下载进度
// Print download Progress
tokio::spawn({
let mut downloaded_len_receiver = downloader.downloaded_len_receiver().clone();
let total_size_future = downloader.total_size_future();
async move {
let total_len = total_size_future.await;
if let Some(total_len) = total_len {
info!("Total size: {:.2} Mb",total_len.get() as f64 / 1024_f64/ 1024_f64);
}
while downloaded_len_receiver.changed().await.is_ok() {
let progress = *downloaded_len_receiver.borrow();
if let Some(total_len) = total_len {
info!("Download Progress: {} %，{}/{}",progress*100/total_len,progress,total_len);
}
tokio::time::sleep(Duration::from_millis(1000)).await;
}
}
});
// 下载速度限制
// Download speed limit
tokio::spawn(async move {
tokio::time::sleep(Duration::from_secs(2)).await;
info!("Start speed limit，开始限速");
speed_limiter.change_speed(Some(1024 * 1024 * 2)).await;
tokio::time::sleep(Duration::from_secs(4)).await;
info!("Remove the download speed limit，解除速度限制");
speed_limiter.change_speed(None).await;
});
info!("Start downloading until the end，开始下载直到结束");
let dec = download_future.await?;
info!("Downloading end cause: {:?}", dec);
Ok(())
}
```
更多用例，请看这里：[Examples](https://github.com/ycysdf/http-downloader/blob/main/examples)