http - 如何使用 Reqwest 设置请求 header ？

Question

我需要使用 Reqwest 库向带有 cookie 的网站发出 GET 请求。我想出了如何发送 GET 请求:

let response = reqwest::get("http://example.com")?;

如何发送相同的请求但添加一些自定义 header ？

Answer 1

请求西0.10

开始于 crate's documentation ，我们看到:

For a single request, you can use the get shortcut method.

get 's documentation状态:

This function creates a new internal Client on each call, and so should not be used if making many requests. Create a Client instead.

Client 有一个 request方法指出:

Returns a RequestBuilder, which will allow setting headers and request body before sending.

RequestBuilder有一个 header method .这可以用作:

use reqwest::header::USER_AGENT;

let client = reqwest::Client::new();
let res = client
    .get("https://www.rust-lang.org")
    .header(USER_AGENT, "My Rust Program 1.0")
    .send()
    .await?;

---

How do I add custom headers?

如果您查看 header 的签名，你会看到它接受通用类型:

pub fn header<K, V>(self, key: K, value: V) -> RequestBuilder where
    HeaderName: TryFrom<K>,
    <HeaderName as TryFrom<K>>::Error: Into<Error>,
    HeaderValue: TryFrom<V>,
    <HeaderValue as TryFrom<V>>::Error: Into<Error>, 

有an implementation of TryFrom<&'a str> for HeaderName ，因此您可以使用字符串文字:

use reqwest; // 0.10.0
use tokio; // 0.2.6

#[tokio::main]
async fn main() -> Result<(), reqwest::Error> {
    let client = reqwest::Client::new();
    let res = client
        .get("https://www.rust-lang.org")
        .header("X-My-Custom-Header", "foo")
        .send()
        .await?;

    Ok(())
}