rocket 创建 http header

来源：https://api.rocket.rs/v0.4/rocket/http/struct.HeaderMap.html

use rocket::http::{HeaderMap, Header};

// The headers we'll be storing.
let all_headers = vec![
    Header::new("X-Custom", "value_1"),
    Header::new("X-Other", "other"),
    Header::new("X-Third", "third"),
];

// Create a map, store all of the headers.
let mut map = HeaderMap::new();
for header in all_headers {
    map.add(header)
}

// Ensure there are three headers via the iterator.
assert_eq!(map.iter().count(), 3);

// Actually iterate through them.
for header in map.iter() {
    match header.name() {
        "X-Custom" => assert_eq!(header.value(), "value_1"),
        "X-Other" => assert_eq!(header.value(), "other"),
        "X-Third" => assert_eq!(header.value(), "third"),
        _ => unreachable!("there are only three headers")
    }
}