这段代码遍历一个文件夹，并查找以.txt结尾的文件。接下来，我想获取std::ffi::os_str::OsStr类型的entry.file_name()，并将其与BASE_URL连接以形成URL。

const FOLDER_NAME: &str = "/tmp";
const PATTERN: &str = ".txt";
const BASE_URL: &str = "http://192.168.1.100:3310/";

use std::error::Error;
use std::ffi::OsStr;
use walkdir::WalkDir;

fn main() -> Result<(), Box<dyn Error>> {
    println!("Walking folder {}", FOLDER_NAME);

    let valid_entries = WalkDir::new(FOLDER_NAME)
        .into_iter()
        .flat_map(|e| e)
        .flat_map(|e| {
            let name = e.file_name().to_str()?;
            if name.contains(PATTERN) {
                Some(e)
            } else {
                None
            }
        });

    print_type_of(&valid_entries);

    for entry in valid_entries {
        println!("This file matches: {:?}", entry);
        let metadata = entry.metadata()?;
        let size = metadata.len();
        let name = entry.file_name();
        let fullpath = entry.path().display();
        println!("path: {}, filename: {:?}, Len: {:?}", fullpath, name, size);
        print_type_of(&name);
        //let url = format!("{}{}",BASE_URL, name); <--- this, how do I do this?
    }
    Ok(())
}

fn print_type_of<T>(_: &T) {
    println!("{}", std::any::type_name::<T>())
}

blowup的示例输出：

error[E0277]: `std::ffi::OsStr` doesn't implement `std::fmt::Display`
--> src/main.rs:34:38
   |
34 |         let url = format!("{}{}",BASE_URL, name);
   |                                            ^^^^ `std::ffi::OsStr` cannot be formatted with the default formatter
   |
   = help: the trait `std::fmt::Display` is not implemented for `std::ffi::OsStr`
   = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead
   = note: required because of the requirements on the impl of `std::fmt::Display` for `&std::ffi::OsStr`
   = note: required by `std::fmt::Display::fmt`

在Go中，我这样做：

video_url := baseURL + *video.Name
req, err := http.NewRequest("HEAD", video_url, nil)
if err != nil {
    log.Println("Err", err)
}

在Rust中正确的方法是什么？
我得到的最接近的是：

let url = format!("{}{:?}", BASE_URL, name);
println!("url {}", url);

其给出：

This file matches: DirEntry("/tmp/a.txt")
path: /tmp/a.txt, filename: "a.txt", Len: 820805
&std::ffi::os_str::OsStr
&str
url http://192.168.1.100:3310/"a.txt"  <- malformed
This file matches: DirEntry("/tmp/somefile.txt")
path: /tmp/somefile.txt, filename: "somefile.txt", Len: 13
&std::ffi::os_str::OsStr
&str
url http://192.168.1.100:3310/"somefile.txt" <- malformed

有了这个，我必须弄清楚如何删除" s。当然感觉有一个更好的方式，我不知道..
既然正确的方法使用了match表达式，那么我如何用它来构建URL呢？

let name = entry.file_name();
let name_to_str = entry.file_name().to_str();
let url = match name_to_str {
        Some(name) =>  format!("{}{:?}",BASE_URL, name_to_str).replace("\"", ""),
        _ => None
};