多线程基础

标签：String Thread 基础 线程 new 多线程 守护 log

ThreadFactory线程工厂
生产线程的工厂，newThread是生产线程的方法，可以定义线程的基本特性。（比如优先级、是否守护线程）   join 调用join方法就会优先执行这个线程（thread1），等执行完毕后才会执行其他线程(thread执行完，再执行主线程)

public static void main(String[] args) throws InterruptedException {
        BaseThread baseThread = new BaseThread();
        Thread thread1 = new Thread(baseThread);

        thread1.start();
        //thread1执行完毕后才会执行主线程
        thread1.join();

        log.info("主线程第二个子线程开始执行------");
        Thread thread2 = new Thread(baseThread);
        thread2.start();
    }

 

锁
锁定部分代码，确保数据准确。配合和synchronized使用，弥补synchronized的不足。

    //生成锁对象
    Lock lock = new ReentrantLock();

    @Override
    public void run() {
        //获取锁
        lock.lock();
        try {
            Thread.sleep(2000);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            //释放锁
            lock.unlock();
        }
        System.out.println(Thread.currentThread().getName() + ": " + new Date());
    }

 

 

Redis设置分布式锁
因为分布式系统使用synchronized和lock只能锁住单台服务器，这样无法确保分布式下这段逻辑准确。

@Autowired
private StringRedisTemplate stringRedisTemplate;

boolean isAccess = false;
String invoiceKey = String.format(ApiRedisKey.AGENT_WITHDRAW_INVOICE, req.getBaseUserId());
try {
    //setIfAbsent 不存在就新增，存在就不改变原有的值。存在返回false,不存在返回true.

    isAccess = stringRedisTemplate.opsForValue().setIfAbsent(invoiceKey, "1", 60, TimeUnit.SECONDS);
    JlpayAssert.isTrue(isAccess, "正在处理，稍后再试");
    //批处理ID(时间戳+用户ID)
    String batchNo = System.currentTimeMillis() + String.format("%010d", req.getBaseUserId());
    InvoiceVo invoiceVo = new InvoiceVo();
    invoiceVo.setBatchNo(batchNo);
    invoiceVo.setLicenseNo(getLicenseNo(req.getBaseUserId()));
    HashMap<String, WithdrawChannelVo> channelMap = getChannelMap();
    invoiceService.saveSubmitInvoice(req, channelMap, invoiceVo);
    FixedThreadPoolUtil.INSTANCE.execute(() -> {
        log.info("提现开票异步任务--开始");
        ThreadContext.put("logid", ContextUtil.getThreadLogId());
        //一般纳税人
        List<WithdrawInvoice> withdrawInvoiceList = invoiceService.getWithdrawInvoiceList(batchNo, TaxType.GENERAL.code, "");
        generalInvoice(batchNo, withdrawInvoiceList);
        //小规模纳税人处理
        HashMap<String, WithdrawChannelVo> smallScaleChannelMap = getSmallScaleChannel();
        smallScaleInvoice(batchNo, smallScaleChannelMap);
        log.info("提现开票异步任务--结束");
    });
} finally {
    if (isAccess) {
        stringRedisTemplate.delete(invoiceKey);
    }
}

 

  run和start的区别

 

线程优先级
线程的优先级由1 -- 10 ，最低是1最高是10，优先级越高越可优先获取cpu去执行任务，但不绝对。

守护线程：

如果 JVM 中没有一个正在运行的非守护线程，这个时候，JVM 会退出。换句话说，守护线程拥有自动结束自己生命周期的特性，而非守护线程不具备这个特点。

 

//创建一个线程

public class DaemonThread implements Runnable {
    @SneakyThrows
    @Override
    public void run() {

        for (int i = 0; i < 10; i++) {
            Thread.sleep(100);
            log.info(Thread.currentThread().getName() + i);
        }
    }
}


//测试守护线程和非守护线程
public static void main(String[] args) throws InterruptedException {
        DaemonThread daemonThread = new DaemonThread();
        Thread thread = new Thread(daemonThread, "daemon thread jason");
        //true为守护线程:主线程结束，子线程也会结束
        //默认false非守护线程：主线程结束，子线程还会继续执行
        thread.setDaemon(true);
        thread.start();
        for (int i = 0; i < 5; i++) {
            Thread.sleep(100);
            log.info(Thread.currentThread().getName() + i);
        }
        log.info("主线程结束---------");
    }

 

主线程结束，守护线程就会结束，非守护线程依然会执行完毕。 

 

标签：String,Thread,基础,线程,new,多线程,守护,log
From： https://www.cnblogs.com/zhougongjin/p/17076248.html