src中创建main.rs

extern crate hyper;    use std::io::Read;  use hyper::Client;    fn main() {      println!("welcome to rust http");      let client = Client::new();      let mut res = client.get("https://httpbin.org/get").send().unwrap();      assert_eq!(res.status, hyper::Ok);      println!("headers:\n {}", res.headers);      let mut body = String::new();      res.read_to_string(&mut body).unwrap();      println!("body:\n {}", body);      res = client.post("https://httpbin.org/post").body("{\"a\":1}").send().unwrap();      assert_eq!(res.status, hyper::Ok);      println!("headers:\n {}", res.headers);      let mut body = String::new();      res.read_to_string(&mut body).unwrap();      println!("body:\n {}", body);  }