Rust日期与时间的操作方法

use std::time::{Duration, Instant};
use std::thread;
fn expensive_function(seconds:u64) {
    thread::sleep(Duration::from_secs(seconds));
}
fn main() {
    cost();
}
fn cost(){
    let start = Instant::now();
    expensive_function(2);
    let duration = start.elapsed();
    println!("耗时: {:?}", duration);
}

use chrono::{Duration, Local};
fn main() {
    // 获取当前时间
    let now = Local::now();
    println!("{}", now);
    let almost_three_weeks_from_now = now.checked_add_signed(Duration::days(1))
            .and_then(|in_2weeks| in_2weeks.checked_add_signed(Duration::weeks(2)))
            .and_then(|in_2weeks| in_2weeks.checked_add_signed(Duration::hours(3)))
            .and_then(|in_2weeks| in_2weeks.checked_add_signed(Duration::seconds(-4)))
            ;
    match almost_three_weeks_from_now {
        Some(x) => println!("{}", x),
        None => eprintln!("时间超出范围"),
    }
    match now.checked_add_signed(Duration::max_value()) {
        Some(x) => println!("{}", x),
        None => eprintln!("时间超出范围，不能计算出太阳系绕银河系中心一周以上的时间."),
    }
}

use chrono::{DateTime, FixedOffset, Local, Utc};
fn main() {
    let local_time = Local::now();
    let utc_time = DateTime::<Utc>::from_naive_utc_and_offset(local_time.naive_utc(), Utc);
    let china_timezone = FixedOffset::east_opt(8 * 3600);
    let rio_timezone = FixedOffset::west_opt(2 * 3600);
    println!("本地时间： {}", local_time);
    println!("UTC时间： {}", utc_time);
    println!(
        "北京时间： {}",
        utc_time.with_timezone(&china_timezone.unwrap())
    );
    println!("里约热内卢时间： {}", utc_time.with_timezone(&rio_timezone.unwrap()));
}

use chrono::{Datelike, Timelike, Local};
fn main() {
    let now = Local::now();
    let (is_common_era, year) = now.year_ce();
    println!(
        "当前年月日： {}-{:02}-{:02} {:?} ({})",
        year,
        now.month(),
        now.day(),
        now.weekday(),
        if is_common_era { "CE" } else { "BCE" }
    );
    let (is_pm, hour) = now.hour12();
    println!(
        "当前时分秒： {:02}:{:02}:{:02} {}",
        hour,
        now.minute(),
        now.second(),
        if is_pm { "PM" } else { "AM" }
    );
}

use chrono::{DateTime, Local, ParseError, NaiveDateTime};
fn main() -> Result<(), ParseError>{
    let now: DateTime<Local> = Local::now();
    // 时间格式化
    let ymdhms =  now.format("%Y-%m-%d %H:%M:%S%.3f");
    // 字符串转时间
    let no_timezone = NaiveDateTime::parse_from_str("2015-09-05 23:56:04.800", "%Y-%m-%d %H:%M:%S%.3f")?;
    println!("当前时间: {}", now);
    println!("时间格式化: {}", ymdhms);
    println!("字符串转时间: {}", no_timezone);
    Ok(())
}