java多线程面试题及答案_java延迟两秒执行

JAVA流控及超流控后的延迟处理实例

本文实例讲述了JAVA流控及超流控后的延迟处理方法。分享给大家供大家参考。具体实现方法如下：

流控检查(每半秒累计，因此最小留空阀值只能做到每秒2条)：

import java.text.SimpleDateFormat;

import java.util.Date;

import java.lang.Thread;

/**

* 流量控制

*

* @author chenx

*/

public class OverflowController {

private int maxSendCountPerSecend; // 该条链路上流控阀值

private Date sendTime = new Date();

private int sendCount = 0; // 该条链路上发送的数量

public OverflowController(int maxSendCountPerSecend) {

if (maxSendCountPerSecend < 2) {

maxSendCountPerSecend = 2;

}

this.maxSendCountPerSecend = maxSendCountPerSecend;

}

public int getMaxSendCountPerSecend() {

if (getMilliseconds(new Date()) >= 500) {

return maxSendCountPerSecend / 2;

}

return maxSendCountPerSecend – (maxSendCountPerSecend / 2);

}

/**

* 是否超流控

*/

public boolean isOverflow(int sendNum) {

synchronized (this) {

Date now = new Date();

if (now.getTime() – sendTime.getTime() >= 500) {

sendTime = now;

sendCount = sendNum;

} else {

if (sendCount + sendNum > getMaxSendCountPerSecend()) {

return true;

} else {

sendCount += sendNum;

}

}

return false;

}

}

/**

* 获取指定时间的毫秒数

*/

private int getMilliseconds(Date date) {

SimpleDateFormat df = new SimpleDateFormat(“SSS”);

return Integer.valueOf(df.format(date));

}

public static void main(String[] args) throws InterruptedException {

OverflowController oc = new OverflowController(50);

SimpleDateFormat df = new SimpleDateFormat(“yyyy-MM-dd HH:mm:ss:SSS”);

for (int i = 0; i <= 100; i++) {

if (oc.isOverflow(1)) {

System.out.println(i + “-isOverflow-” + df.format(new Date()));

} else {

System.out.println(i + “-sendOk-” + df.format(new Date()));

}

Thread.sleep(10);

}

}

}

超流控后的延迟处理，由于java中没有.net的“延迟委托”一说：

ThreadPool.RegisterWaitForSingleObject(

WaitHandle waitObject,

WaitOrTimerCallback callBack,

Object state,

int millisecondsTimeOutInterval,

bool executeOnlyOnce

)

Java下需实现一个简单的延迟队列：

import java.util.concurrent.Delayed;

import java.util.concurrent.TimeUnit;

public class DelayEntry implements Delayed {

private int count;

private long dequeuedTimeMillis; // 出队列时间

public int getCount() {

return count;

}

public void setCount(int count) {

this.count = count;

}

public long getDequeuedTimeMillis() {

return dequeuedTimeMillis;

}

public DelayEntry(long delayMillis) {

dequeuedTimeMillis = System.currentTimeMillis() + delayMillis;

}

@Override

public int compareTo(Delayed o) {

DelayEntry de = (DelayEntry) o;

long timeout = dequeuedTimeMillis – de.dequeuedTimeMillis;

return timeout > 0 ? 1 : timeout < 0 ? -1 : 0;

}

@Override

public long getDelay(TimeUnit unit) {

return dequeuedTimeMillis – System.currentTimeMillis();

}

}

import java.util.concurrent.DelayQueue;

public class DelayService {

public void run() {

DelayQueue queue = new DelayQueue();

DelayConsumer delayConsumer = new DelayConsumer(queue);

delayConsumer.start();

for (int i = 0; i < 100; i++) {

DelayEntry de = new DelayEntry(5000);

de.setCount(i);

System.out.println(System.currentTimeMillis() + “——–” + de.getCount());

queue.add(de);

}

}

class DelayConsumer extends Thread {

DelayQueue queue;

public DelayConsumer(DelayQueue queue) {

this.queue = queue;

}

public void run() {

while (true) {

try {

DelayEntry de = queue.take();

System.out.println(“queue size=” + queue.size());

System.out.println(de.getCount());

System.out.println(System.currentTimeMillis());

} catch (InterruptedException e) {

e.printStackTrace();

}

}

}

}

public static void main(String[] args) {

DelayService ds = new DelayService();

ds.run();

}

}

希望本文所述对大家的Java程序设计有所帮助。相关阅读:

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