hyper

pub struct Error { /* private fields */ }
pub type Result<T> = Result<T, Error>;

pub async fn handshake<T, B>( io: T, ) -> Result<(SendRequest<B>, Connection<T, B>)> //
where
    T: Read + Write + Unpin,
    B: Body + 'static,
    B::Data: Send,
    B::Error: Into<Box<dyn StdError + Send + Sync>>,

// 发送请求
impl<B> SendRequest<B> where B: Body + 'static
    // Sends a Request on the associated connection.
    pub fn send_request( &mut self, req: Request<B>, ) -> impl Future<Output = Result<Response<IncomingBody>>>


// 示例：创建一个缺省 http1 client，使用 hyper::client::conn::http1::Builder 来个性化配置
let (mut sender, conn) = hyper::client::conn::http1::handshake(io).await?;
let mut res = sender.send_request(req).await?;
while let Some(next) = res.frame().await {
    let frame = next?;
    if let Some(chunk) = frame.data_ref() { // 获取 frame 中数据，chunk 类型是 bytes::Bytes
        io::stdout().write_all(&chunk).await?;
    }
}
// let body = res.collect().await?.aggregate();

#![deny(warnings)]
#![warn(rust_2018_idioms)]
use std::env;
use bytes::Bytes;
use http_body_util::{BodyExt, Empty};
use hyper::Request;
use tokio::io::{self, AsyncWriteExt as _};
use tokio::net::TcpStream;

#[path = "../benches/support/mod.rs"]
mod support;
use support::TokioIo;

// A simple type alias so as to DRY.
type Result<T> = std::result::Result<T, Box<dyn std::error::Error + Send + Sync>>;

#[tokio::main]
async fn main() -> Result<()> {
    pretty_env_logger::init();

    // Some simple CLI args requirements...
    let url = match env::args().nth(1) {
        Some(url) => url,
        None => {
            println!("Usage: client <url>");
            return Ok(());
        }
    };

    // HTTPS requires picking a TLS implementation, so give a better warning if the
    // user tries to request an 'https' URL.
    let url = url.parse::<hyper::Uri>().unwrap();
    if url.scheme_str() != Some("http") {
        println!("This example only works with 'http' URLs.");
        return Ok(());
    }

    fetch_url(url).await
}

async fn fetch_url(url: hyper::Uri) -> Result<()> {
    let host = url.host().expect("uri has no host");
    let port = url.port_u16().unwrap_or(80);
    let addr = format!("{}:{}", host, port);

    let stream = TcpStream::connect(addr).await?;
    let io = TokioIo::new(stream);

    // 创建一个缺省的 http1 client，也可以使用 hyper::client::conn::http1::Builder 来
    // 个性化配置 client 参数。
    let (mut sender, conn) = hyper::client::conn::http1::handshake(io).await?;

    tokio::task::spawn(async move {
        if let Err(err) = conn.await {
            println!("Connection failed: {:?}", err);
        }
    });

    let authority = url.authority().unwrap().clone();
    let path = url.path();
    let req = Request::builder()
        .uri(path)
        .header(hyper::header::HOST, authority.as_str())
        .body(Empty::<Bytes>::new())?; // 使用 http_body_util::Empty 来设置空的 Request Body.

    // res 是 Struct hyper::Response 类型，实现了 hyper::body::Body trait 即
    // http_body::Body trait，具体类型是 Struct hyper::body::Incoming
    let mut res = sender.send_request(req).await?;

    println!("Response: {}", res.status());
    println!("Headers: {:#?}\n", res.headers());

    // res 是 Struct hyper::body::Incoming 类型，实现了 http_body::Body 和
    // http_body_util::BodyExt trait 这里调用 BodyExt 提供的 frame() 方法，
    while let Some(next) = res.frame().await {
        let frame = next?;
        if let Some(chunk) = frame.data_ref() { // 获取 frame 中数据，chunk 类型是 bytes::Bytes
            io::stdout().write_all(&chunk).await?;
        }
    }

    // 或者使用 http_body_util::BodyExt 提供的 collect() 方法，一次聚合所有 Body 的内容。

    // asynchronously aggregate the chunks of the body
    // let body = res.collect().await?.aggregate();
    // // try to parse as json with serde_json
    // let users = serde_json::from_reader(body.reader())?;

    Ok(users)

    println!("\n\nDone!");
    Ok(())
}