JAVA日期安全格式化之SimpleDateFormat和jodaTime,DateTimeFormatter

SimpleDateFormat线程不安全的日期格式化库

SimpleDateFormat是 JAVA提供的一个日期转换类。

package com.rumenz.task;

import java.text.SimpleDateFormat;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;

//线程不安全
public class DataFormat {

    private static SimpleDateFormat simpleDateFormat=new SimpleDateFormat("yyyyMMdd");
    private static Integer clientTotal=5000;
    private static Integer threadTotal=200;

    public static void main(String[] args) throws Exception{
        ExecutorService executorService = Executors.newCachedThreadPool();
        final Semaphore semaphore=new Semaphore(threadTotal);
        final CountDownLatch countDownLatch=new CountDownLatch(clientTotal);
        for (int i = 0; i {
                try{
                    semaphore.acquire();
                    update();
                    semaphore.release();
                }catch (Exception e){
                    e.printStackTrace();
                }
                countDownLatch.countDown();
            });

        }
        countDownLatch.await();
        executorService.shutdown();


    }

    private static void update() {
        try{
            simpleDateFormat.parse("20200115");
        }catch (Exception e){
            e.printStackTrace();
        }

    }
}

运行的时候回报错,线程不安全

java.lang.NumberFormatException: For input string: "E152"
    at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:2043)
    at sun.misc.FloatingDecimal.parseDouble(FloatingDecimal.java:110)
    at java.lang.Double.parseDouble(Double.java:538)
    at java.text.DigitList.getDouble(DigitList.java:169)
    at java.text.DecimalFormat.parse(DecimalFormat.java:2089)
    at java.text.SimpleDateFormat.subParse(SimpleDateFormat.java:1867)
    at java.text.SimpleDateFormat.parse(SimpleDateFormat.java:1514)
    at java.text.DateFormat.parse(DateFormat.java:364)
    at com.rumenz.task.DataFormat.update(DataFormat.java:47)
    at com.rumenz.task.DataFormat.lambda$main$0(DataFormat.java:30)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)

如果要使用 SimpleDateFormat可以将其做成局部变量,这样在多线程环境下就不会出现线程安全问题。或者使用 synchronized给方法加锁。

jodaTime 线程安全的格式化库

引入依赖

  joda-time
  joda-time
  2.9.9

package com.keytech.task;

import org.joda.time.DateTime;

import java.time.format.DateTimeFormatter;
import java.time.temporal.TemporalAccessor;
import java.util.Date;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;

//线程安全
public class DataFormat1 {

    public static Integer clientTotal=5000;
    public static Integer threadTotal=200;
    private static DateTimeFormatter dateTimeFormatter=DateTimeFormatter.ofPattern("yyyyMMdd");

    public static void main(String[] args)  throws Exception{
        ExecutorService executorService = Executors.newCachedThreadPool();
        final Semaphore semaphore=new Semaphore(threadTotal);
        final CountDownLatch countDownLatch=new CountDownLatch(clientTotal);
        for (int i = 0; i < clientTotal; i++) {
            executorService.execute(()->{
                try{
                    semaphore.acquire();
                    update();
                    semaphore.release();

                }catch (Exception e){
                    e.printStackTrace();
                }
                countDownLatch.countDown();
            });

        }
        countDownLatch.await();
        executorService.shutdown();
    }

    private static void update() {
        DateTime dateTime = DateTime.parse("20200115").toDateTime();
        System.out.println(dateTime);
    }
}

DateTimeFormatter JAVA8中线程安全的日期转换类

package com.keytech.task;

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;

//线程安全
public class DateFormat2 {

    public static Integer clientTotal=5000;
    public static Integer threadTotal=200;
    private  static final  DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMdd");

    public static void main(String[] args) throws Exception{
        ExecutorService executorService = Executors.newCachedThreadPool();
        final Semaphore semaphore=new Semaphore(threadTotal);
        final CountDownLatch countDownLatch=new CountDownLatch(clientTotal);

        for (int i = 0; i < clientTotal; i++) {
            try{
                semaphore.acquire();
                update();
                semaphore.release();
            }catch (Exception e){
                e.printStackTrace();
            }
            countDownLatch.countDown();

        }

        countDownLatch.await();
        executorService.shutdown();

    }

    private static void update() {
        LocalDate localDate = LocalDate.parse("20200115", formatter);
        System.out.println(localDate);

    }
}

JAVA8中自带,直接可以使用,不需要引入其它的库。

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