Rust:如何从文件中读取十六进制

use std::fs::File;
use std::io::Read;

fn read_file() -> Result<Vec<u8>, std::io::Error> {
    let mut file = File::open("file.txt")?;
    let mut buffer = Vec::new();
    file.read_to_end(&mut buffer)?;
    Ok(buffer)
}

use hex;

fn parse_hex(buffer: &[u8]) -> Result<String, hex::FromHexError> {
    let hex_string = hex::encode(buffer);
    Ok(hex_string)
}

use std::fs::File;
use std::io::Read;
use hex;

fn read_hex_from_file() -> Result<String, Box<dyn std::error::Error>> {
    let mut file = File::open("file.txt")?;
    let mut buffer = Vec::new();
    file.read_to_end(&mut buffer)?;

    let hex_string = hex::encode(&buffer);
    Ok(hex_string)
}