java 排队实现_Java实现排队论的原理
引入：
前段時(shí)間去銀行辦業(yè)務(wù)，排隊(duì)的人那是真多，自己正式辦理業(yè)務(wù)也就不到5分鐘，但是卻足足等了兩個(gè)小時(shí)(相信很多人都遇到過這種情況)，對(duì)這種服務(wù)水平真的是無語了，但是問題又來了，銀行應(yīng)該開幾個(gè)窗口，既能保證整體的服務(wù)質(zhì)量，又能保證資源資源的利用率呢？下面我們就通過排隊(duì)論來模擬這個(gè)問題。
排隊(duì)論簡介
排隊(duì)論是研究系統(tǒng)隨機(jī)聚散現(xiàn)象和隨機(jī)系統(tǒng)工作工程的數(shù)學(xué)理論和方法，又稱隨機(jī)服務(wù)系統(tǒng)理論，為運(yùn)籌學(xué)的一個(gè)分支。我們下面對(duì)排隊(duì)論做下簡化處理，先看下圖：
我們?cè)趫D的左側(cè)安排若干個(gè)藍(lán)色服務(wù)臺(tái)，右側(cè)為可能會(huì)過來的紅色顧客，中間為黃色的等候區(qū)，如果有服務(wù)臺(tái)處于空閑狀態(tài)，顧客可以直接去接受服務(wù)，否則就要在黃色區(qū)域等候，顧客服務(wù)的順序采用先到現(xiàn)服務(wù)的原則，現(xiàn)在如果我們知道顧客過來的概率分布，那么我們?cè)谧髠?cè)安排幾個(gè)服務(wù)臺(tái)既能達(dá)到更好的服務(wù)水平，又能保證服務(wù)臺(tái)的使用率？下面我們就構(gòu)建模型來模擬這個(gè)問題。
排隊(duì)論分步實(shí)現(xiàn)
1)對(duì)于排隊(duì)論，我們首先要確定顧客屬性，知道顧客什么時(shí)候到達(dá)，需要的服務(wù)耗時(shí)等，我們首先創(chuàng)建一個(gè)顧客類，在這里我們指定了顧客服務(wù)的最大、最小時(shí)間，這里我們?yōu)榱撕喕椭苯诱J(rèn)為服務(wù)時(shí)間完全隨機(jī)：
public class CustomerBean {
//最小服務(wù)時(shí)間
private static int minServeTime = 3 * 1000;
//最大服務(wù)時(shí)間
private static int maxServeTime = 15 * 1000;
//顧客達(dá)到時(shí)間
private long arriveTime;
//顧客需要服務(wù)耗時(shí)
private int serveTime;
public CustomerBean() {
//設(shè)置到達(dá)時(shí)間
arriveTime = System.currentTimeMillis();
//隨機(jī)設(shè)置顧客的服務(wù)時(shí)間
serveTime = (int) (Math.random() * (maxServeTime - minServeTime) + minServeTime);
}
}
2)上面我們定義了顧客，緊接著就需要定義一個(gè)排隊(duì)隊(duì)列，我們先看下隊(duì)列的屬性，這里我們定義一個(gè)數(shù)組，用它來保存排隊(duì)的顧客，定義下一個(gè)顧客到來的最小、最大時(shí)間間隔以及顧客來不來的概率(這里簡單說明下，如果下一個(gè)顧客的間隔時(shí)間是3，但是通過概率計(jì)算并為滿足，則這個(gè)顧客不進(jìn)入隊(duì)列，這樣設(shè)置的原因是盡可能的使顧客達(dá)到有很大的隨機(jī)性)和隊(duì)列中最大的排隊(duì)人數(shù)。
public class CustomerQuene {
//等待顧客隊(duì)列
private LinkedList customers = new LinkedList();
//下一個(gè)顧客過來最短時(shí)間
private int minTime = 0;
//下一個(gè)顧客過來最大時(shí)間
private int maxTime = 1 * 1000;
//來顧客的概率
private double rate = 0.9;
//標(biāo)識(shí)是否繼續(xù)產(chǎn)生顧客
private boolean flag = true;
//最大排隊(duì)人數(shù)
private int maxWaitNum = 0;
}
3)顧客和排隊(duì)的隊(duì)列都有了，我們就設(shè)置一個(gè)產(chǎn)生顧客的線程，讓它不斷的產(chǎn)生顧客，這里就有我們上面說的時(shí)間和概率分布。
/**
*@Description: 生成顧客線程
*@Version:1.1.0
*/
private class CustomerThread extends Thread {
private CustomerThread(String name) {
super(name);
}
@Override
public void run() {
while (flag) {
//隊(duì)尾添加一個(gè)新顧客
if (Math.random() < rate) {
customers.addLast(new CustomerBean());
if (maxWaitNum < customers.size()) {
maxWaitNum = customers.size();
}
}
int sleepTime = (int) (Math.random() * (maxTime - minTime) + minTime);
try {
TimeUnit.MILLISECONDS.sleep(sleepTime);
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
4)如果隊(duì)列中有顧客排隊(duì)切有空閑的服務(wù)臺(tái)，就需要獲取隊(duì)頭的顧客去接受服務(wù)
public synchronized CustomerBean getCustomerBean() {
if (customers == null || customers.size() < 1) {
return null;
}
return customers.removeFirst();
}
5)顧客相關(guān)的屬性和方法都已經(jīng)準(zhǔn)備好，下面就設(shè)置下服務(wù)臺(tái)相關(guān)的屬性，這里我們直接把服務(wù)臺(tái)設(shè)置成線程，定義一些服務(wù)指標(biāo)，如服務(wù)的顧客數(shù)目、總等待時(shí)間、總服務(wù)時(shí)間、最大等待時(shí)間等。
public class ServantThread extends Thread{
//服務(wù)顧客數(shù)目
private static int customerNum = 0;
//總等待時(shí)間
private static int sumWaitTime = 0;
//總服務(wù)時(shí)間
private static int sumServeTime = 0;
//最大等待時(shí)間
private static int maxWaitTime = 0;
private boolean flag = false;
private String name;
}
6)服務(wù)臺(tái)最主要的工作就是服務(wù)顧客，這里我們把服務(wù)顧客相關(guān)的操作寫到線程的run方法中。
public void run() {
flag = true;
while (flag) {
CustomerBean customer = CustomerQuene.getCustomerQuene().getCustomerBean();
//如果顧客線程已經(jīng)關(guān)閉且隊(duì)列中沒有顧客，服務(wù)臺(tái)線程關(guān)閉釋放
if (customer == null) {
if (!CustomerQuene.getCustomerQuene().isFlag()) {
flag = false;
print();
}
continue;
}
long now = System.currentTimeMillis();
int waitTime = (int) (now - customer.getArriveTime());
//保存最大的等待時(shí)間
if (waitTime > maxWaitTime) {
maxWaitTime = waitTime;
}
//睡眠時(shí)間為顧客的服務(wù)時(shí)間，代表這段時(shí)間在服務(wù)顧客
try {
TimeUnit.MILLISECONDS.sleep(customer.getServeTime());
} catch (Exception e) {
e.printStackTrace();
}
System.err.println(name + " 服務(wù)顧客耗時(shí)：" + customer.getServeTime() + "ms\t顧客等待：" + waitTime + "ms");
customerNum++;
sumWaitTime += waitTime;
sumServeTime += customer.getServeTime();
}
}
7)最后我們編寫一個(gè)測(cè)試模型，來驗(yàn)證服務(wù)水平
/**
*@Description:
*/
package com.lulei.opsearch.quene;
import java.util.concurrent.TimeUnit;
public class Test {
public static void main(String[] args) {
//開門
System.out.println("開門接客啦！");
boolean flag = true;
CustomerQuene.getCustomerQuene();
long a = System.currentTimeMillis();
int servantNum = 10;
for (int i = 0; i < servantNum; i++) {
ServantThread thread = new ServantThread("服務(wù)臺(tái)" + i);
thread.start();
}
while (flag) {
long b = System.currentTimeMillis();
if (b - a > 1 * 60 * 1000 && flag) {
//關(guān)門
flag = false;
CustomerQuene.getCustomerQuene().close();
System.out.println("關(guān)門不接客啦！");
}
System.out.println("系統(tǒng)運(yùn)行時(shí)間：" + (b -a) + "ms");
System.out.println("系統(tǒng)空閑時(shí)間：" + ((b -a) * servantNum - ServantThread.getSumServeTime()));
ServantThread.print();
try {
TimeUnit.SECONDS.sleep(2);
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
運(yùn)行結(jié)果
1)運(yùn)行開始
2)顧客產(chǎn)生線程關(guān)閉
3)最后服務(wù)水平
通過修改服務(wù)臺(tái)的個(gè)數(shù)就可以評(píng)估在當(dāng)前的顧客情況下應(yīng)該設(shè)置幾個(gè)服務(wù)臺(tái)。
完整代碼
1)顧客類
/**
*@Description:
*/
package com.lulei.opsearch.quene;
public class CustomerBean {
//最小服務(wù)時(shí)間
private static int minServeTime = 3 * 1000;
//最大服務(wù)時(shí)間
private static int maxServeTime = 15 * 1000;
//顧客達(dá)到時(shí)間
private long arriveTime;
//顧客需要服務(wù)耗時(shí)
private int serveTime;
public CustomerBean() {
//設(shè)置到達(dá)時(shí)間
arriveTime = System.currentTimeMillis();
//隨機(jī)設(shè)置顧客的服務(wù)時(shí)間
serveTime = (int) (Math.random() * (maxServeTime - minServeTime) + minServeTime);
}
public static int getMinServeTime() {
return minServeTime;
}
public static void setMinServeTime(int minServeTime) {
CustomerBean.minServeTime = minServeTime;
}
public static int getMaxServeTime() {
return maxServeTime;
}
public static void setMaxServeTime(int maxServeTime) {
CustomerBean.maxServeTime = maxServeTime;
}
public long getArriveTime() {
return arriveTime;
}
public void setArriveTime(long arriveTime) {
this.arriveTime = arriveTime;
}
public int getServeTime() {
return serveTime;
}
public void setServeTime(int serveTime) {
this.serveTime = serveTime;
}
}
2)顧客隊(duì)列
/**
*@Description:
*/
package com.lulei.opsearch.quene;
import java.util.LinkedList;
import java.util.concurrent.TimeUnit;
public class CustomerQuene {
//等待顧客隊(duì)列
private LinkedList customers = new LinkedList();
//下一個(gè)顧客過來最短時(shí)間
private int minTime = 0;
//下一個(gè)顧客過來最大時(shí)間
private int maxTime = 1 * 1000;
//來顧客的概率
private double rate = 0.9;
//標(biāo)識(shí)是否繼續(xù)產(chǎn)生顧客
private boolean flag = true;
//最大排隊(duì)人數(shù)
private int maxWaitNum = 0;
public int getMaxWaitNum() {
return maxWaitNum;
}
public boolean isFlag() {
return flag;
}
/**
* @return
* @Author:lulei
* @Description: 獲取排在隊(duì)頭的顧客
*/
public synchronized CustomerBean getCustomerBean() {
if (customers == null || customers.size() < 1) {
return null;
}
return customers.removeFirst();
}
public void close() {
if (flag) {
flag = false;
}
}
/**
* @return
* @Author:lulei
* @Description: 獲取等待顧客數(shù)量
*/
public int getWaitCustomerNum() {
return customers.size();
}
/**
*@Description: 生成顧客線程
*@Version:1.1.0
*/
private class CustomerThread extends Thread {
private CustomerThread(String name) {
super(name);
}
@Override
public void run() {
while (flag) {
//隊(duì)尾添加一個(gè)新顧客
if (Math.random() < rate) {
customers.addLast(new CustomerBean());
if (maxWaitNum < customers.size()) {
maxWaitNum = customers.size();
}
}
int sleepTime = (int) (Math.random() * (maxTime - minTime) + minTime);
try {
TimeUnit.MILLISECONDS.sleep(sleepTime);
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
//單例模式開始
private static class CustomerQueneDao {
private static CustomerQuene customerQuene = new CustomerQuene();
}
private CustomerQuene() {
CustomerThread customerThread = new CustomerThread("顧客產(chǎn)生線程");
customerThread.start();
}
public static CustomerQuene getCustomerQuene() {
return CustomerQueneDao.customerQuene;
}
//單例模式結(jié)束
public int getMinTime() {
return minTime;
}
public void setMinTime(int minTime) {
this.minTime = minTime;
}
public int getMaxTime() {
return maxTime;
}
public void setMaxTime(int maxTime) {
this.maxTime = maxTime;
}
public double getRate() {
return rate;
}
public void setRate(double rate) {
this.rate = rate;
}
}
3)服務(wù)臺(tái)線程
/**
*@Description:
*/
package com.lulei.opsearch.quene;
import java.util.concurrent.TimeUnit;
import com.lulei.util.ParseUtil;
public class ServantThread extends Thread{
//服務(wù)顧客數(shù)目
private static int customerNum = 0;
//總等待時(shí)間
private static int sumWaitTime = 0;
//總服務(wù)時(shí)間
private static int sumServeTime = 0;
//最大等待時(shí)間
private static int maxWaitTime = 0;
private boolean flag = false;
private String name;
public ServantThread(String name) {
super(name);
this.name = name;
}
public static int getMaxWaitTime() {
return maxWaitTime;
}
public static int getSumServeTime() {
return sumServeTime;
}
@Override
public void run() {
flag = true;
while (flag) {
CustomerBean customer = CustomerQuene.getCustomerQuene().getCustomerBean();
//如果顧客線程已經(jīng)關(guān)閉且隊(duì)列中沒有顧客，服務(wù)臺(tái)線程關(guān)閉釋放
if (customer == null) {
if (!CustomerQuene.getCustomerQuene().isFlag()) {
flag = false;
print();
}
continue;
}
long now = System.currentTimeMillis();
int waitTime = (int) (now - customer.getArriveTime());
//保存最大的等待時(shí)間
if (waitTime > maxWaitTime) {
maxWaitTime = waitTime;
}
//睡眠時(shí)間為顧客的服務(wù)時(shí)間，代表這段時(shí)間在服務(wù)顧客
try {
TimeUnit.MILLISECONDS.sleep(customer.getServeTime());
} catch (Exception e) {
e.printStackTrace();
}
System.err.println(name + " 服務(wù)顧客耗時(shí)：" + customer.getServeTime() + "ms\t顧客等待：" + waitTime + "ms");
customerNum++;
sumWaitTime += waitTime;
sumServeTime += customer.getServeTime();
}
}
public static void print() {
if (customerNum > 0) {
System.out.println("--------------------------------------");
System.out.println("服務(wù)顧客數(shù)目：" + customerNum);
System.out.println("最大等待時(shí)間：" + maxWaitTime);
System.out.println("等待顧客數(shù)目：" + CustomerQuene.getCustomerQuene().getWaitCustomerNum());
System.out.println("最大等待顧客數(shù)目：" + CustomerQuene.getCustomerQuene().getMaxWaitNum());
//輸出顧客平均等待時(shí)間，保留兩位小數(shù)
System.out.println("顧客平均等待時(shí)間：" + ParseUtil.parseDoubleToDouble((sumWaitTime * 1.0 / customerNum), 2) + "ms");
System.out.println("顧客平均服務(wù)時(shí)間：" + ParseUtil.parseDoubleToDouble((sumServeTime * 1.0 / customerNum), 2) + "ms");
System.out.println("系統(tǒng)總服務(wù)時(shí)間：" + sumServeTime + "ms");
}
}
}
4)測(cè)試模型
/**
*@Description:
*/
package com.lulei.opsearch.quene;
import java.util.concurrent.TimeUnit;
public class Test {
public static void main(String[] args) {
//開門
System.out.println("開門接客啦！");
boolean flag = true;
CustomerQuene.getCustomerQuene();
long a = System.currentTimeMillis();
int servantNum = 10;
for (int i = 0; i < servantNum; i++) {
ServantThread thread = new ServantThread("服務(wù)臺(tái)" + i);
thread.start();
}
while (flag) {
long b = System.currentTimeMillis();
if (b - a > 1 * 60 * 1000 && flag) {
//關(guān)門
flag = false;
CustomerQuene.getCustomerQuene().close();
System.out.println("關(guān)門不接客啦！");
}
System.out.println("系統(tǒng)運(yùn)行時(shí)間：" + (b -a) + "ms");
System.out.println("系統(tǒng)空閑時(shí)間：" + ((b -a) * servantNum - ServantThread.getSumServeTime()));
ServantThread.print();
try {
TimeUnit.SECONDS.sleep(2);
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
以上就是關(guān)于Java實(shí)現(xiàn)排隊(duì)論的原理詳細(xì)介紹，希望對(duì)大家的學(xué)習(xí)有所幫助。
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