Rust 使用 chrono 處理日期時間
chrono 旨在成爲時間庫的一個功能完整的超集。它嚴格遵守 ISO 8601，默認包含時區，也有不含時區的類型。
1，先來一個小點心，測量函數耗費時間，使用的標準庫 time。
use std::thread;
use std::time::{Duration, Instant};
fn expensive_function() {
thread::sleep(Duration::from_secs(1));
}
fn main() {
let start = Instant::now();
expensive_function();
let duration = start.elapsed();
println!("Time elapsed in expensive_function() is: {:?}", duration);
}
// 打印結果
Time elapsed in expensive_function() is: 1.0122099s2，獲取當前時間
use chrono::prelude::*;
let utc: DateTime<Utc> = Utc::now(); // e.g. `2014-11-28T12:45:59.324310806Z`
let local: DateTime<Local> = Local::now(); // e.g. `2014-11-28T21:45:59.324310806+09:00`
println!("the utc is {},the local is {}", utc, local);
// 打印結果
the utc is 2023-07-01 01:50:40.050821800 UTC,the local is 2023-07-01 09:50:40.050837400 +08:003，日期計算，計算 1 周後，3 天前等。
use chrono::{Duration, Local};
fn main() {
let now = Local::now();
println!("{}", now);
let after_one_week = now.checked_add_signed(Duration::weeks(1)).unwrap();
let three_day_earlier = now.checked_sub_signed(Duration::days(3)).unwrap();
println!(
"now is {},now after one week is {},and now before three days is {}.",
now, after_one_week, three_day_earlier
);
}
// 打印結果
now is 2023-07-01 09:54:01.195332500 +08:00,now after one week is 2023-07-08 09:54:01.195332500 +08:00,and now before three days is 2023-06-28 09:54:01.195332500
+08:00.4，日期和時間戳相互轉換
use chrono::{DateTime, TimeZone, Utc};
fn main() {
// 時間戳轉爲日期
let dt = Utc.timestamp_opt(1_500_000_000, 0).unwrap();
println!("the date is {}.", dt.to_rfc2822());
// 日期轉爲時間戳
let dt = DateTime::parse_from_rfc2822("Fri, 14 Jul 2017 02:40:00 +0000").unwrap();
println!("the timestamp is {}.", dt.timestamp());
}
// 打印結果
the date is Fri, 14 Jul 2017 02:40:00 +0000.
the timestamp is 1500000000.5，日期格式化
use chrono::{DateTime, Local, Utc};
fn main() {
let now: DateTime<Utc> = Utc::now();
println!("UTC now is: {}", now);
println!("UTC now in RFC 2822 is: {}", now.to_rfc2822());
println!("UTC now in RFC 3339 is: {}", now.to_rfc3339());
println!(
"UTC now in a custom format is: {}",
now.format("%a %b %e %T %Y")
);
println!(
"UTC now in a custom format is: {}",
now.format("%Y-%m-%d %H:%M:%S")
);
let now = Local::now();
println!("Local now is: {}", now);
println!("Local now in RFC 2822 is: {}", now.to_rfc2822());
println!("Local now in RFC 3339 is: {}", now.to_rfc3339());
println!(
"Local now in a custom format is: {}",
now.format("%a %b %e %T %Y")
);
println!(
"Local now in a custom format is: {}",
now.format("%Y-%m-%d %H:%M:%S")
);
}
// 打印結果
UTC now is: 2023-07-01 02:12:41.864372800 UTC
UTC now in RFC 2822 is: Sat, 01 Jul 2023 02:12:41 +0000
UTC now in RFC 3339 is: 2023-07-01T02:12:41.864372800+00:00
UTC now in a custom format is: Sat Jul 1 02:12:41 2023
UTC now in a custom format is: 2023-07-01 02:12:41
Local now is: 2023-07-01 10:12:41.865922200 +08:00
Local now in RFC 2822 is: Sat, 01 Jul 2023 10:12:41 +0800
Local now in RFC 3339 is: 2023-07-01T10:12:41.865922200+08:00
Local now in a custom format is: Sat Jul 1 10:12:41 2023
Local now in a custom format is: 2023-07-01 10:12:416，字符串轉爲日期
use chrono::format::ParseError;
use chrono::{DateTime, FixedOffset, TimeZone, Utc};
fn main() -> Result<(), ParseError> {
// 方法1
let date1 = "2014-11-28T12:00:09Z".parse::<DateTime<Utc>>().unwrap();
println!("date1 is {}.", date1);
let date2 = "2014-11-28T21:00:09+09:00"
.parse::<DateTime<Utc>>()
.unwrap();
println!("date2 is {}.", date2);
let date3 = "2014-11-28T21:00:09+09:00"
.parse::<DateTime<FixedOffset>>()
.unwrap();
println!("date3 is {}.", date3);
// 方法2
let date1 =
DateTime::parse_from_str("2014-11-28 21:00:09 +09:00", "%Y-%m-%d %H:%M:%S %z").unwrap();
println!("date1 is {}.", date1);
let date2 = DateTime::parse_from_rfc2822("Fri, 28 Nov 2014 21:00:09 +0900").unwrap();
println!("date2 is {}.", date2);
let date3 = DateTime::parse_from_rfc3339("2014-11-28T21:00:09+09:00").unwrap();
println!("date3 is {}.", date3);
// 方法3
let date1 = Utc
.datetime_from_str("2014-11-28 12:00:09", "%Y-%m-%d %H:%M:%S")
.unwrap();
println!("date1 is {}.", date1);
let date2 = Utc
.datetime_from_str("Fri Nov 28 12:00:09 2014", "%a %b %e %T %Y")
.unwrap();
println!("date2 is {}.", date2);
Ok(())
}
// 打印結果
date1 is 2014-11-28 12:00:09 UTC.
date2 is 2014-11-28 12:00:09 UTC.
date3 is 2014-11-28 21:00:09 +09:00.
date1 is 2014-11-28 21:00:09 +09:00.
date2 is 2014-11-28 21:00:09 +09:00.
date3 is 2014-11-28 21:00:09 +09:00.
date1 is 2014-11-28 12:00:09 UTC.
date2 is 2014-11-28 12:00:09 UTC.7，獲取日期的年月日和時分秒等信息
use chrono::{Datelike, FixedOffset, NaiveDate, TimeZone, Timelike};
fn main() {
let now = FixedOffset::east_opt(9 * 3600)
.unwrap()
.from_local_datetime(
&NaiveDate::from_ymd_opt(2014, 11, 28)
.unwrap()
.and_hms_nano_opt(21, 45, 59, 324310806)
.unwrap(),
)
.unwrap();
println!("now is {}.", now);
// 獲取時分秒
let (is_pm, hour) = now.hour12();
println!(
"The current time is {:02}:{:02}:{:02} {}",
hour,
now.minute(),
now.second(),
if is_pm { "PM" } else { "AM" }
);
println!(
"And there have been {} seconds since midnight",
now.num_seconds_from_midnight()
);
let (is_common_era, year) = now.year_ce();
println!(
"The current date is {}-{:02}-{:02} {:?} ({})",
year,
now.month(),
now.day(),
now.weekday(),
if is_common_era { "CE" } else { "BCE" }
);
println!(
"The week of year is {:?},and the day of year is {}",
now.iso_week(),
now.ordinal(),
);
println!(
"And the Common Era began {} days ago",
now.num_days_from_ce()
);
}
// 打印結果
now is 2014-11-28 21:45:59.324310806 +09:00.
The current time is 09:45:59 PM
And there have been 78359 seconds since midnight
The current date is 2014-11-28 Fri (CE)
The week of year is 2014-W48,and the day of year is 332
And the Common Era began 735565 days ago更多內容請查看 https://docs.rs/chrono/0.4.26/chrono/
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來源：https://mp.weixin.qq.com/s/GANz4u_b6Q2nMMERDkW7PA