Java多线程环境下SimpleDateFormat类安全转换
一、SimpleDateFormat类
package state; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Date; /** * SimpleDateFormat类负责日期的转换与格式化 * 解决SimpleDateFormat类多线程环境下转换错误问题 * @author zc * */ public class SimpleDateFormatThread extends Thread{ private SimpleDateFormat sdf; private String dateString; public SimpleDateFormatThread(SimpleDateFormat sdf,String dateString) { super(); this.sdf =sdf; this.dateString =dateString; } @Override public void run() { try { //System.out.println(dateString); //刚开始日期格式设置错误为YYYY-MM-dd Date date =DateTools.getSimpleDateFormat("yyyy-MM-dd").parse(dateString); // System.out.println(date); String newDateString =DateTools.getSimpleDateFormat("yyyy-MM-dd").format(date).toString(); if(!newDateString.equals(dateString)) { System.out.println("ThreadName="+this.getName()+"报错日期"+dateString+" 转换日期"+newDateString); }else { System.out.println("ThreadName="+this.getName()+"日期"+dateString+" 转换日期"+newDateString); } } catch (ParseException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public static void main(String[] args) { SimpleDateFormat sdf =new SimpleDateFormat("yyyy-MM-dd"); String[] dateStringArray =new String[]{ "2020-02-05","2020-02-06","2020-02-07","2020-02-08" }; SimpleDateFormatThread []threadArray= new SimpleDateFormatThread[4]; for(int i=0;i<4;i++) { threadArray[i] =new SimpleDateFormatThread(sdf,dateStringArray[i]); } for(int i=0;i<4;i++) { threadArray[i].start(); } } } class DateTools{ //ThreadLocal能使线程绑定到指定的对象 private static ThreadLocal<SimpleDateFormat> t = new ThreadLocal<SimpleDateFormat>(); public static SimpleDateFormat getSimpleDateFormat(String datePattern) { SimpleDateFormat sdf=null; sdf =t.get(); if(sdf==null) { sdf =new SimpleDateFormat(datePattern); t.set(sdf); } return sdf; } }
二、线程状态和线程组
(2)线程5状态 //NEW 尚未启动的线程 //RUNNABLE Java虚拟机中执行的线程 //TERMINATED 已经退出的线程 //BLOCKED 阻塞受监视的线程 //WAITING 无限等待另一个线程 //TIMED_WAITING 等待另一个线程指定时间 package state; /** * 线程中状态和线程组 * @author zc * */ public class MyThread extends Thread{ //NEW //RUNNABLE //TERMINATED //BLOCKED //WAITING //TIMED_WAITING public MyThread() { System.out.println("构造方法中的状态: "+Thread.currentThread().getState()); } @Override public void run() { System.out.println("run方法中的状态:"+Thread.currentThread().getState()); try { Thread.sleep(1000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public static void main(String[] args) { MyThread myThread = new MyThread(); System.out.println("main方法中的状态1 "+ myThread.getState()); Thread t1 = new Thread(); Thread t2 = new Thread(); ThreadGroup group =new ThreadGroup("左氏线程组"); Thread t3 = new Thread(group,t1); Thread t4 = new Thread(group,t2); t3.start(); t4.start(); System.out.println("活动的线程数量为: " +group.activeCount()); System.out.println("线程组的名称为: "+group.getName()); try { myThread.start(); Thread.sleep(1000); System.out.println("main方法中的状态2 "+ myThread.getState()); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }
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