Chrono Code

• DateTime - Utc的时间（2022-12-06 05:22:19.808711 UTC）
• DateTime - 本地的带Timezone的时间（2022-12-06 14:22:19.808810 +09:00）
• DateTime - 从Utc时间有N个小时偏移的时间（2022-12-06T12:00:00+09:00）
• NaiveDateTime - 不带Timezone的时间（2022-12-06T14:25:43.600317）

use chrono::{DateTime, FixedOffset, Local, NaiveDateTime, TimeZone, Utc};
fn main() {
let utc_datetime = Utc::now();
let utc_date = Utc::now().date_naive();
println!("utc_datetime is : {}", utc_datetime); // 2022-12-06 05:25:43.599886 UTC
println!("utc_date is : {}", utc_date); // 2022-12-06

let local_datetime = Local::now();
let local_date = Local::now().date_naive();

println!("local_datetime is : {}", local_datetime); // 2022-12-06 14:25:43.600005 +09:00
println!("local_date is : {}", local_date); // 2022-12-06

022-12-06T12:00:00+09:00:00" x
let dt = DateTime::parse_from_rfc3339("2022-12-06T12:00:00+09:00");
println!("after parse dt is : {:?}", dt); // Ok(2022-12-06T12:00:00+09:00)

ateTime::parse_from_str("2022/12/06 12:00:00 +0900", "%Y/%m/%d %H:%M:%S") x
let dt_from_str = DateTime::parse_from_str("2022/12/06 12:00:00 +0900", "%Y/%m/%d %H:%M:%S %z");
println!("after parse dt_from_str is : {:?}", dt_from_str); // 2022-12-06T12:00:00+09:00

let dt_utc = Utc.datetime_from_str("2022-12-06 14:01:00", "%Y-%m-%d %H:%M:%S");
println!("after parse dt_utc is : {:?}", dt_utc); // 2022-12-06T14:01:00Z

let dt_local = Local.datetime_from_str("2022-12-06 14:01:00", "%Y-%m-%d %H:%M:%S");
println!("after parse dt_local is : {:?}", dt_local); // 2022-12-06T14:01:00+09:00

// 不带偏移量的时间
let dt_navie = NaiveDateTime::parse_from_str("2022-12-06 14:01:00", "%Y-%m-%d %H:%M:%S");
println!("after parse dt_navie is : {:?}", dt_navie); // 2022-12-06T14:01:00

// format
let text = Utc::now().format("%Y年%m月%d日").to_string();
println!("after format text is : {:?}", text); // 2022年12月06日

// Tz -> no Tz
let utc = Utc::now();
let navie_local = utc.naive_local();
println!("navie_local is : {:?}", navie_local); // 2022-12-06T05:13:14.821945

let navie_utc = utc.naive_utc();
println!("navie_utc is : {:?}", navie_utc); // 2022-12-06T05:13:58.176283

let local = Local::now();
let local_navie = local.naive_local();
println!("local_navie is : {:?}", local_navie); // 2022-12-06T14:16:16.096215

let local_utc = local.naive_utc();
println!("local_utc is : {:?}", local_utc); // 2022-12-06T05:16:16.096215

// no Tz -> Tz
let dt: NaiveDateTime =
    NaiveDateTime::parse_from_str("2018/12/07 19:31:28", "%Y/%m/%d %H:%M:%S").unwrap();
let utc = Utc.from_local_datetime(&dt).unwrap();
println!("utc is : {:?}", utc); // 2018-12-07T19:31:28Z

let local = Local.from_local_datetime(&dt).unwrap();
println!("local is : {:?}", local); // 2018-12-07T19:31:28+09:00

let offset = FixedOffset::east_opt(8 * 3600)
    .unwrap()
    .from_local_datetime(&dt)
    .unwrap();
println!("offset is : {:?}", offset); // 2018-12-07T19:31:28+08:00

// 日期的计算
let dt1 = NaiveDateTime::parse_from_str("2022-12-06 14:01:00", "%Y-%m-%d %H:%M:%S").unwrap();
let dt2 = NaiveDateTime::parse_from_str("2021-12-06 14:01:00", "%Y-%m-%d %H:%M:%S").unwrap();
let duration = dt1 - dt2;
println!("duration seconds is : {:?}", duration.num_seconds()); // 31536000
println!("duration minutes is : {:?}", duration.num_minutes()); // 525600
println!("duration hours is : {:?}", duration.num_hours()); // 8760
println!("duration days is : {:?}", duration.num_days()); // 365

}