ThreadLocal 解决simpledateformat线程不安全

package com.example.demo.util;

import java.text.SimpleDateFormat;

public class DateFormatUtil {
    private  static ThreadLocal<SimpleDateFormat> simpleDateFormatThreadLocal=new ThreadLocal<SimpleDateFormat>(){
        @Override
        protected SimpleDateFormat initialValue() {
            return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        }
    };

    public static SimpleDateFormat getSimpleDateFormat(){
        return simpleDateFormatThreadLocal.get();
    }
}

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package com.example.demo.time;

import com.example.demo.util.DateFormatUtil;

import java.text.SimpleDateFormat;
import java.util.Date;

public class TestDate {
    public static void main(String[] args) {
        for (int i=0;i<10;i++){
            new Thread(new Runnable() {
                @Override
                public void run() {
                    //注意 一定不要用一个栈指向多个引用
                    SimpleDateFormat simpleDateFormat = DateFormatUtil.getSimpleDateFormat();
                    String now = simpleDateFormat.format(new Date());

                    try {
                        Date dd = simpleDateFormat.parse(now);
                        String ff = simpleDateFormat.format(dd);
                        if(ff.equals(now)){
                            System.out.println("1111111111");
                        }else {
                            System.out.println("000000000");
                        }
                    } catch (Exception e) {
                        e.printStackTrace();
                    }

                }
            }).start();
        }

    }
}