ThreadLocal解决线程安全问题

package com.javacodegeeks.test;import java.text.DateFormat;import java.text.ParseException;import java.text.SimpleDateFormat;import java.util.Date;public class ConcurrentDateFormatAccess { private ThreadLocal<DateFormat> df = new ThreadLocal<DateFormat> () {  @Override  public DateFormat get() {   return super.get();  }  @Override  protected DateFormat initialValue() {   return new SimpleDateFormat("yyyy MM dd");  }  @Override  public void remove() {   super.remove();  }  @Override  public void set(DateFormat value) {   super.set(value);  } }; public Date convertStringToDate(String dateString) throws ParseException {  return df.get().parse(dateString); }}