JAVA流控及超流控後的延遲處理實例

本文實例講述了JAVA流控及超流控後的延遲處理方法。分享給大家供大家參考。具體實作方法如下：

流控檢查（每半秒累計，因此最小留空閥值只能做到每秒2條）：

複製程式碼如下:import java.text.SimpleDateFormat;
import java.util.Date;
import java.lang.Thread;

/**
* 流量控制
*
* @author chenx
*/
public class OverflowController {

private int maxSendCountPerSecend; // 此條鏈路上流控閥值
private Date sendTime = new Date();
private int sendCount = 0; // 該條鏈路上發送的數量

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;
}
}

/**
* 取得指定時間的毫秒數
*/
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);
}
}
}
超流控後的延遲處理，由於java中沒有.net的「延遲委託」一說：
複製程式碼如下:ThreadPool.RegisterWaitForSingleObject(
WaitHandle waitObject,
WaitOrTimerCallback callBack,
Object state,
int millisecondsTimeOutInterval,
bool executeOnlyOnce
)

Java下需實作一個簡單的延遲佇列：

複製程式碼如下:import java.util.concurrent.Delayed;
import java.util.concurrent.TimeUnit;

public class DelayEntry implements Delayed {

private int count;
private long dequeuedTimeMillis; // 出佇列時間

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();
}
}

複製程式碼如下:import java.util.concurrent.DelayQueue;

public class DelayService {

public void run() {
DelayQueue<DelayEntry> queue = new DelayQueue<DelayEntry>();
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<DelayEntry> queue;
public DelayConsumer(DelayQueue<DelayEntry> 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();
}
}

希望本文所述對大家的Java程式設計有幫助。