Tokio和Serde：反序列化JSON

问题描述

当尝试从tokio Value反序列化为JSON Tcpstream时，我正在尝试使用以下功能：

use futures::prelude::*;
use serde_json::Value;
use tokio::io::{AsyncReadExt,AsyncWriteExt};
use tokio::net::{TcpListener,Tcpstream};
use tokio::stream::StreamExt;
use tokio_serde_json::ReadJson;
use tokio_util::codec::{FramedRead,LengthDelimitedCodec};

pub async fn handle_stream(mut stream: Tcpstream) {
    let length_delimited = FramedRead::new(stream,LengthDelimitedCodec::new());
    let mut deserialized = ReadJson::<_,Value>::new(length_delimited);
}

我的依赖版本为：

tokio = { version = "0.2.22",features=["full"] }
tokio-util = { version = "0.3.0",features=["full"] }
tokio-serde = "0.6"
serde = "1.0.92"
serde_derive = "1.0.92"
serde_json = "1.0.39"
futures-preview = "0.3.0-alpha"

我从examples from carllerche/tokio-serde-json

获得了代码

但是我遇到以下错误：

error[E0277]: the trait bound `tokio_util::codec::framed_read::FramedRead<tokio::net::tcp::stream::Tcpstream,tokio_util::codec::length_delimited::LengthDelimitedCodec>: futures::stream::Stream` is not satisfied
   --> src/kad2.rs:141:58
    |
141 |         let mut deserialized = ReadJson::<_,Value>::new(length_delimited);
    |                                                          ^^^^^^^^^^^^^^^^ the trait `futures::stream::Stream` is not implemented for `tokio_util::codec::framed_read::FramedRead<tokio::net::tcp::stream::Tcpstream,tokio_util::codec::length_delimited::LengthDelimitedCodec>`
    |
    = note: required by `tokio_serde_json::ReadJson::<T,U>::new`

这是API和推荐库的一种情况，它已经进化并转移到另一种做事方式了吗？ 我现在如何使用Tokio将JSON反序列化为Value？

解决方法

这个仓库似乎被另一个仓库抛弃了：

之前：tokio-serde-json

之后：tokio-serde

https://github.com/carllerche/tokio-serde/blob/master/examples/server.rs

我用过这个服务器代码：

use futures::prelude::*;
use serde_json::Value;
use tokio::net::TcpListener;
use tokio_serde::formats::*;
use tokio_util::codec::{FramedRead,LengthDelimitedCodec};

#[tokio::main]
pub async fn main() {
    // Bind a server socket
    let listener = TcpListener::bind("127.0.0.1:17653").await.unwrap();

    println!("listening on {:?}",listener.local_addr());

    loop {
        let (socket,_) = listener.accept().await.unwrap();

        // Delimit frames using a length header
        let length_delimited = FramedRead::new(socket,LengthDelimitedCodec::new());

        // Deserialize frames
        let mut deserialized = tokio_serde::SymmetricallyFramed::new(
            length_delimited,SymmetricalJson::<Value>::default(),);

        // Spawn a task that prints all received messages to STDOUT
        tokio::spawn(async move {
            while let Some(msg) = deserialized.try_next().await.unwrap() {
                println!("GOT: {:?}",msg);
            }
        });
    }
}

具有以下依赖项：

[dependencies]
futures = "0.3"
impls = "1"
tokio = { version = "1.0",features = ["full"] }
tokio-util = { version = "0.6",features = ["codec"] }
static_assertions = "1.1.0"
serde_json = "1.0"
tokio-serde = { version = "0.8",features = ["json"] }

并且编译运行成功。