我试图使用hyper获取HTML页面的内容，并希望同步返回future 的输出.我意识到我本可以 Select 一个更好的例子，因为同步HTTP请求已经存在，但我更感兴趣的是理解我们是否可以从异步计算中返回值.

extern crate futures;
extern crate hyper;
extern crate hyper_tls;
extern crate tokio;

use futures::{future, Future, Stream};
use hyper::Client;
use hyper::Uri;
use hyper_tls::HttpsConnector;

use std::str;

fn scrap() -> Result<String, String> {
    let scraped_content = future::lazy(|| {
        let https = HttpsConnector::new(4).unwrap();
        let client = Client::builder().build::<_, hyper::Body>(https);

        client
            .get("https://hyper.rs".parse::<Uri>().unwrap())
            .and_then(|res| {
                res.into_body().concat2().and_then(|body| {
                    let s_body: String = str::from_utf8(&body).unwrap().to_string();
                    futures::future::ok(s_body)
                })
            }).map_err(|err| format!("Error scraping web page: {:?}", &err))
    });

    scraped_content.wait()
}

fn read() {
    let scraped_content = future::lazy(|| {
        let https = HttpsConnector::new(4).unwrap();
        let client = Client::builder().build::<_, hyper::Body>(https);

        client
            .get("https://hyper.rs".parse::<Uri>().unwrap())
            .and_then(|res| {
                res.into_body().concat2().and_then(|body| {
                    let s_body: String = str::from_utf8(&body).unwrap().to_string();
                    println!("Reading body: {}", s_body);
                    Ok(())
                })
            }).map_err(|err| {
                println!("Error reading webpage: {:?}", &err);
            })
    });

    tokio::run(scraped_content);
}

fn main() {
    read();
    let content = scrap();

    println!("Content = {:?}", &content);
}

示例编译后，对read()的调用成功，但对scrap()的调用出现以下错误消息:

Content = Err("Error scraping web page: Error { kind: Execute, cause: None }")

我明白，在future 致电.wait()之前，我没有正确启动任务，但我找不到正确的方法，假设这是可能的.