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我正在尝试使用 Hyper 在 Rust 中创建一个简单的 Web 服务器，但在尝试将其转换request.body() Stream为String.

我每晚运行 rustc 1.21.0

到目前为止，我有这个：

extern crate futures;
extern crate hyper;
extern crate unicase;

use hyper::server::{Http, Request, Response, Service};
use hyper::Body;
use hyper::Chunk;
use futures::Stream;
use futures::future::*;
use futures::stream::Map;
use std::ascii::AsciiExt;
use unicase::Ascii;

struct WebService;

impl Service for WebService {
    type Request = Request;
    type Response = Response;
    type Error = hyper::Error;
    type Future = Box<futures::Future<Item = Self::Response, Error = Self::Error>>;

    fn call(&self, req: Request) -> Self::Future {
        let mut response = Response::new();

        let body = req.body()
            .fold(Vec::new(), |mut acc, chunk| {
                acc.extend_from_slice(&*chunk);
                futures::future::ok::<_, Self::Error>(acc)
            })
            .and_then(|v| String::from_utf8(v));
        println!("Body: \n{}", body.wait().unwrap());

        let future = futures::future::ok(response);
        Box::new(future)
    }
}

fn main() {
    let addr = "0.0.0.0:3000".parse().unwrap();
    let server = Http::new().bind(&addr, || Ok(WebService)).unwrap();
    server.run().unwrap();
}

这会导致以下错误消息：

error[E0271]: type mismatch resolving `<std::result::Result<std::string::String, std::string::FromUtf8Error> as futures::IntoFuture>::Error == hyper::Error`
  --> src/main.rs:30:14
   |
30 |             .and_then(|v| String::from_utf8(v));
   |              ^^^^^^^^ expected struct `std::string::FromUtf8Error`, found enum `hyper::Error`
   |
   = note: expected type `std::string::FromUtf8Error`
              found type `hyper::Error`

error[E0599]: no method named `wait` found for type `futures::AndThen<futures::stream::Fold<hyper::Body, [closure@src/main.rs:26:31: 29:14], futures::FutureResult<std::vec::Vec<u8>, hyper::Error>, std::vec::Vec<u8>>, std::result::Result<std::string::String, std::string::FromUtf8Error>, [closure@src/main.rs:30:23: 30:47]>` in the current scope
  --> src/main.rs:31:37
   |
31 |         println!("Body: \n{}", body.wait().unwrap());
   |                                     ^^^^
   |
   = note: the method `wait` exists but the following trait bounds were not satisfied:
           `futures::AndThen<futures::stream::Fold<hyper::Body, [closure@src/main.rs:26:31: 29:14], futures::FutureResult<std::vec::Vec<u8>, hyper::Error>, std::vec::Vec<u8>>, std::result::Result<std::string::String, std::string::FromUtf8Error>, [closure@src/main.rs:30:23: 30:47]> : futures::Stream`
           `futures::AndThen<futures::stream::Fold<hyper::Body, [closure@src/main.rs:26:31: 29:14], futures::FutureResult<std::vec::Vec<u8>, hyper::Error>, std::vec::Vec<u8>>, std::result::Result<std::string::String, std::string::FromUtf8Error>, [closure@src/main.rs:30:23: 30:47]> : futures::Future`

我认为我正在从该fold方法返回一个未来，其结果被输送到该and_then方法中，我希望该方法将一个String版本分配request.body给该body变量。

我对 Rust 很陌生，但对我来说，错误似乎表明and_then连接器只接收Error未来的价值，而不是Ok价值......

这是一个正确的解释吗？我将如何解决此错误？

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0 回答 0