使用reqwest::get，去执行一个 HTTP GET 请求，然后使用Document::from_read将响应解析为 HTML 文档。拿find，配上Name标准“a”，检索所有链接。在Selection上，调用filter_map留下链接中 URL，包含“href”attr的。

# #[macro_use]
# extern crate error_chain;
extern crate reqwest;
extern crate select;

use select::document::Document;
use select::predicate::Name;
#
# error_chain! {
#    foreign_links {
#        ReqError(reqwest::Error);
#        IoError(std::io::Error);
#    }
# }

fn run() -> Result<()> {
    let res = reqwest::get("https://www.rust-lang.org/en-US/")?;

    Document::from_read(res)?
        .find(Name("a"))
        .filter_map(|n| n.attr("href"))
        .for_each(|x| println!("{}", x));

    Ok(())
}
#
# quick_main!(run);

调用get_base_url以检索 base URL。如果文档有 base 标签，从 base 标签获取attr。Position::BeforePath作为 原始 URL 的 默认行为。

遍历文档中的链接，并用url::ParseOptions和Url::parse解析。用 reqwest 对链接做请求，并验证StatusCode。

# #[macro_use]
# extern crate error_chain;
extern crate reqwest;
extern crate select;
extern crate url;

use std::collections::HashSet;

use url::{Url, Position};
use reqwest::StatusCode;
use select::document::Document;
use select::predicate::Name;
#
# error_chain! {
#   foreign_links {
#       ReqError(reqwest::Error);
#       IoError(std::io::Error);
#       UrlParseError(url::ParseError);
#   }
# }

fn get_base_url(url: &Url, doc: &Document) -> Result<Url> {
    let base_tag_href = doc.find(Name("base")).filter_map(|n| n.attr("href")).nth(0);

    let base_url = base_tag_href.map_or_else(
        || Url::parse(&url[..Position::BeforePath]),
        Url::parse,
    )?;

    Ok(base_url)
}

fn check_link(url: &Url) -> Result<bool> {
    let res = reqwest::get(url.as_ref())?;

    Ok(res.status() != StatusCode::NOT_FOUND)
}

fn run() -> Result<()> {
    let url = Url::parse("https://www.rust-lang.org/en-US/")?;

    let res = reqwest::get(url.as_ref())?;
    let document = Document::from_read(res)?;

    let base_url = get_base_url(&url, &document)?;

    let base_parser = Url::options().base_url(Some(&base_url));

    let links: HashSet<Url> = document
        .find(Name("a"))
        .filter_map(|n| n.attr("href"))
        .filter_map(|link| base_parser.parse(link).ok())
        .collect();

    links
        .iter()
        .filter(|link| check_link(link).ok() == Some(false))
        .for_each(|x| println!("{} is broken.", x));

    Ok(())
}
#
# quick_main!(run);

使用reqwest::get，拉取 MediaWiki 源页面，然后Regex::captures_iter查找内部和外部链接的所有条目。使用Cow避免过度String分配 (单一)。

极客学院：Cow

Mediawiki 链接语法，在这里有所描述。

# #[macro_use]
# extern crate error_chain;
#[macro_use]
extern crate lazy_static;
extern crate reqwest;
extern crate regex;

use std::io::Read;
use std::collections::HashSet;
use std::borrow::Cow;
use regex::Regex;

# error_chain! {
#     foreign_links {
#         Io(std::io::Error);
#         Reqwest(reqwest::Error);
#         Regex(regex::Error);
#     }
# }
#
fn extract_links(content: &str) -> Result<HashSet<Cow<str>>> {
    lazy_static! {
        static ref WIKI_REGEX: Regex =
            Regex::new(r"(?x)
                \[\[(?P<internal>[^\[\]|]*)[^\[\]]*\]\]    # internal links
                |
                (url=|URL\||\[)(?P<external>http.*?)[ \|}] # external links
            ").unwrap();
    }

    let links: HashSet<_> = WIKI_REGEX
        .captures_iter(content)
        .map(|c| match (c.name("internal"), c.name("external")) {
            (Some(val), None) => Cow::from(val.as_str().to_lowercase()),
            (None, Some(val)) => Cow::from(val.as_str()),
            _ => unreachable!(),
        })
        .collect();

    Ok(links)
}

fn run() -> Result<()> {
    let mut content = String::new();
    reqwest::get(
        "https://en.wikipedia.org/w/index.php?title=Rust_(programming_language)&action=raw",
    )?
        .read_to_string(&mut content)?;

    println!("{:#?}", extract_links(&content)?);

    Ok(())
}
#
# quick_main!(run);