Java8新特性——————SimpleDateFormat格式化的线程安全问题

今天药忘吃喽~ 2023-07-10 08:12 6阅读 0赞

#### 传统时间格式化的线程安全问题 ####

在使用SimpleDateFormat时间格式处理类会出现线程安全问题，而java8新特性中的 DateTimeFormatter时间格式处理类解决了此问题，代码如下：

@Test
        public static void main(String[] args)throws Exception { 
            //出现线程安全问题：异常信息为java.lang.NumberFormatException: For input string: ".22E1.22E1"
    /* SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd"); Callable<Date> callable = new Callable<Date>() { @Override public Date call() throws Exception { return sdf.parse("20200220"); } };*/
            //加锁后操作
    /* Callable<Date> callable = new Callable<Date>() { @Override public Date call() throws Exception { return DateFormatThreadLocal.convert("20200220"); } };*/
            //java8时间处理类
            DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyyMMdd");
            Callable<LocalDate> callable = new Callable<LocalDate>() { 
                @Override
                public LocalDate call() throws Exception { 
                    return LocalDate.parse("20200220",dtf);
                }
            };
            ExecutorService pool = Executors.newFixedThreadPool(10);
            List<Future<LocalDate>> futures = new ArrayList<>();
            for (int i = 0; i < 10; i++) { 
                futures.add(pool.submit(callable));
            }
            for (Future<LocalDate> future : futures) { 
                System.out.println(future.get());
            }
            pool.shutdown();
        }

//加锁
    class  DateFormatThreadLocal{ 
        private  static final ThreadLocal<DateFormat> df = new ThreadLocal<DateFormat>(){ 
            @Override
            protected DateFormat initialValue() { 
                return new SimpleDateFormat("yyyyMMdd");
            }
        };
    
        public static  Date convert(String source) throws ParseException { 
            return df.get().parse(source);
        }

#### 计算两个"时间"之间的间隔 ####

@Test
    public static void main(String[] args)throws Exception {
        Instant ins1 = Instant.now();
        Thread.sleep(10000);
        Instant ins2 = Instant.now();
        Duration durantion = Duration.between(ins1, ins2);
        System.out.println(durantion.toMillis());//10000毫秒
    }