高性能且线程安全的两种格式化日期方式

package util;

import java.text.SimpleDateFormat;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Date;

public class TimeUtil {
    private ThreadLocal<SimpleDateFormat> threadLocal=new ThreadLocal<SimpleDateFormat>() {
        public SimpleDateFormat initialValue() {
            SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");
            return sdf;
        }
    };
    
    private SimpleDateFormat getDateFormat() {
        return threadLocal.get();
    }
    
    public String formatDate(Date date) {
        SimpleDateFormat sdf=getDateFormat();
        return sdf.format(date);
    }
    
    public static void main(String[] args) {
        // High performance,thread-safe method 1
        TimeUtil tu=new TimeUtil();
        System.out.println(tu.formatDate(new Date()));
        
        // High performance,thread-safe method 2
        DateTimeFormatter formatter=DateTimeFormatter.ofPattern("yyyy-MM-dd");
        LocalDateTime now=LocalDateTime.now();
        String str=formatter.format(now);
        System.out.println(str);
    }
}

输出：

2020-04-15
2020-04-15

--2020-04-15--