SimpleDateFormat线程不安全问题

来源：互联网发布：数据库过滤器编辑：程序博客网时间：2024/06/05 20:05

导致SimpleDateFormat出现多线程安全问题的原因，是因为：SimpleDateFormat处理复杂，Jdk的实现中使用了成员变量来传递参数，这就造成在多线程的时候会出现错误

一些常见的错误代码大致如下

public class DateFormatTest {    private static SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");     xxxxxx...}

错误浮现dmo

package dateFormat;import java.text.SimpleDateFormat;import java.util.Date;public class DateFormatTest {    private static SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");    public static void main(String[] args) {        Date today = new Date();        Date tomorrow = new Date(today.getTime() + 1000 * 60 * 60 * 24);        System.out.println(today);         System.out.println(tomorrow);         Thread thread1 = new Thread(new Thread1(dateFormat, today));        thread1.start();        Thread thread2 = new Thread(new Thread2(dateFormat, tomorrow));        thread2.start();    }}class Thread1 implements Runnable {    private SimpleDateFormat dateFormat;    private Date date;    public Thread1(SimpleDateFormat dateFormat, Date date) {        this.dateFormat = dateFormat;        this.date = date;    }    public void run() {        for (;;) {            System.out.println("Thread1.run" + date);            String strDate = dateFormat.format(date);                        if (!"2015-11-03".equals(strDate)) {                System.err.println("today=" + strDate);                System.exit(0);            }        }    }}class Thread2 implements Runnable {    private SimpleDateFormat dateFormat;    private Date date;    public Thread2(SimpleDateFormat dateFormat, Date date) {        this.dateFormat = dateFormat;        this.date = date;    }    public void run() {        for (;;) {            System.out.println("Thread2.run" + date);            String strDate = dateFormat.format(date);            if (!"2015-11-04".equals(strDate)) {                System.err.println("tomorrow=" + strDate);                System.exit(0);            }        }    }}

最笨的解决办法：不使用static SimpleDateFormat，每次使用都直接new一个

比较高大上的解决办法joda

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