java 多线程之Worker Thread模式(Thread Pool模式)

Worker Thread模式

Worker的意思是工作的人，在Worker Thread模式中，工人线程Worker thread会逐个取回工作并进行处理，当所有工作全部完成后，工人线程会等待新的工作到来。

Worker Thread模式也被成为Background Thread（背景线程）模式，另外，如果从保存多个工人线程的场所这一点看，我们也可以称这种模式为Thread Pool模式。

Worker Thread模式中的角色

TransPortThread [将部件塞到传送带上]（委托者）
创建表示工作请求的Cargo并将其传递给SimpleChannel 。在示例程序中，TransPortThread 相当于该角色。

2.SimpleChannel [传送带的角色]（通信线路）
SimpleChannel 角色接受来自于TransPortThread 的Cargo，并将其传递给WorkerThread。在示例程序中，SimpleChannel 相当于该角色。

3.WorkerThread（工人）
WorkerThread角色从Channel中获取Cargo，并进行工作，当一项工作完成后，它会继续去获取另外的Cargo，在示例程序中，WorkerThread相当于该角色。

4.Cargo（部件）
Cargo角色是表示工作中的部件，Cargo角色中保存了进行工作所必须的信息，在示例程序中，Cargo相当于该部件角色。

Worker Thread使用场景

想象这样一个场景，一个工厂在生产货物，在一个车间里，有几个工人，每次生产部件准备后，车间外的人就将部件放到车间的传送带上，工人每次做完一个货品就从桌子上取部件。在这里，注意到，部件并不是直接交给工人的，另外一点，工人并不是做完一个部件就回家换个新人，后者在现实有点滑稽，但是在程序中却对应一个典型的线程使用方法：线程池。

所谓线程池，就是对线程的复用，当线程执行完任务之后就继续取其他任务执行，而不是销毁启动新线程执行其他任务。因为线程的启动对于系统性能开销比较大，所以这样对于系统性能的提高很有好处。

Main.java

public class WorkClient {public static void main(String[] args) {// 创建容量为5的SimpleChannel实例（数据缓冲通道）SimpleChannel simpleChannel = new SimpleChannel(5);// 启动工作通道开始处理数据（消费者启动）simpleChannel.startWork();// 启动三个数据传输线程（生产者角色）new TransPortThread("june", simpleChannel).start();new TransPortThread("july", simpleChannel).start();new TransPortThread("alen", simpleChannel).start();}}

Cargo.java

角色：部件或货物

import java.util.Optional;/*** 货物类，包含货物编号和名称，并提供执行操作时打印线程执行信息的功能** @author [请填写作者名称]* @version 1.0*/
public class Cargo {/*** 货物名称*/private final String name;/*** 货物编号*/private final int num;/*** 构造方法，初始化货物信息** @param name 货物名称* @param num  货物编号*/public Cargo(String name, int num) {this.name = name;this.num = num;}/*** 执行货物处理操作，打印当前线程名称和货物信息*/public void execute(){Optional.of(Thread.currentThread().getName()+" executed "+this.toString()).ifPresent(System.out::println);}/*** 获取货物信息的字符串表示** @return 格式化后的货物信息（例如：Cargo ==> NO.123 Name.ItemA）*/@Overridepublic String toString() {return "Cargo ==> NO."+num+" Name."+name;}
}

SimpleChannel.java

职责：将部件或货物从源头传给处理端

import java.util.Arrays;/*** 简单线程通信通道，管理货物队列和工作线程池* 使用环形缓冲区实现生产者-消费者模式，通过synchronized和wait/notify机制保证线程安全*/
public class SimpleChannel {/** 缓冲区最大容量 */private static final int BUFFER_SIZE = 100;/** 环形缓冲区数组，存储货物对象 */private final Cargo[] cargoQueue;/** 队列头指针，指向下一个要取出的元素位置 */private int headIndex;/** 当前队列中的元素数量 */private int count;/** 队列尾指针，指向下一个要插入的元素位置 */private int tailIndex;/** 工作线程池 */private final WorkerThread[] workerPool;/*** 构造方法初始化通道* @param workerCount 工作线程数量*/public SimpleChannel(int workerCount) {this.cargoQueue = new Cargo[BUFFER_SIZE];this.headIndex = 0;this.count = 0;this.tailIndex = 0;this.workerPool = new WorkerThread[workerCount];this.init();}/*** 初始化工作线程池* 为每个线程设置名称并绑定当前通道实例*/private void init() {for (int i = 0; i < workerPool.length; i++) {workerPool[i] = new WorkerThread("worker-"+i, this);}}/*** 启动所有工作线程开始工作* 通过遍历线程池调用start()方法启动每个线程*/public void startWork() {Arrays.asList(workerPool).forEach(WorkerThread::start);}/*** 生产者添加货物到缓冲区* @param cargo 要添加的货物对象* @throws InterruptedException 线程中断异常*/public synchronized void pushCargo(Cargo cargo) {while (count >= BUFFER_SIZE) {try {this.wait(); // 缓冲区满时等待} catch (InterruptedException e) {// 异常处理（建议补充日志）}}// 添加货物到尾部并更新指针this.cargoQueue[tailIndex] = cargo;this.tailIndex = (this.tailIndex + 1) % this.cargoQueue.length;this.count++;this.notifyAll(); // 通知等待线程}/*** 消费者从缓冲区取出货物* @return 取出的货物对象* @throws InterruptedException 线程中断异常*/public synchronized Cargo popCargo() {while (count <= 0) {try {this.wait(); // 缓冲区空时等待} catch (InterruptedException e) {// 异常处理（建议补充日志）}}// 取出头部元素并更新指针Cargo cargo = this.cargoQueue[headIndex];this.headIndex = (this.headIndex + 1) % this.cargoQueue.length;this.count--;this.notifyAll(); // 通知等待线程return cargo;}
}

TransPortThread .java

职责：将请求的信息塞到传输通道上去

/*** 运输线程，负责持续生成货物并推送到传输通道 {@link SimpleChannel}*/
public class TransPortThread extends Thread {private SimpleChannel simpleChannel;/*** 静态随机数生成器，用于生成随机休眠时间*/private static final Random RANDOM = new Random(System.currentTimeMillis());/*** 构造方法** @param name 线程名称* @param simpleChannel 货物传输通道*/public TransPortThread(String name, SimpleChannel simpleChannel) {super(name);this.simpleChannel = simpleChannel;}@Overridepublic void run() {try {int i = 0;// 无限循环持续生成货物while (true){Cargo cargo = new Cargo(getName(), i++); // 创建货物对象（包含线程名和序号）this.simpleChannel.pushCargo(cargo);   // 将货物推送到通道Thread.sleep(RANDOM.nextInt(1000));    // 随机休眠 0-1000ms}} catch (InterruptedException e) {// 线程中断时的异常处理（当前空实现）}}
}

WorkerThread.java

职责：从传输带上获取部件或货物

import java.util.Random;
/*** 工作线程类，负责从共享通道中持续获取任务并执行*/
public class WorkerThread extends Thread {/*** 存储任务通道实例，用于获取待处理的任务对象*/private final SimpleChannel simpleChannel;/*** 静态随机数生成器，用于生成随机休眠时间（模拟任务执行间隔）*/private static final Random random = new Random(System.currentTimeMillis());/*** 构造方法初始化线程名称和任务通道* @param name 线程名称标识* @param simpleChannel 任务通道对象，用于获取待处理任务*/public WorkerThread(String name, SimpleChannel simpleChannel) {super(name);this.simpleChannel = simpleChannel;}/*** 线程执行主体方法，持续循环执行以下操作：* 1. 从通道中获取任务对象* 2. 执行任务* 3. 随机休眠（模拟任务处理间隔）*/@Overridepublic void run() {while (true) {try {// 从通道中获取任务对象Cargo cargo = simpleChannel.popCargo();// 执行任务逻辑cargo.execute();// 随机休眠0-1000毫秒（模拟任务间隔）Thread.sleep(random.nextInt(1000));} catch (Exception e) {// 异常处理：打印堆栈信息（实际应用中建议添加更完善的异常处理）e.printStackTrace();}}}
}

执行的结果

worker-1 executed Cargo ==> NO.0 Name.alen
worker-0 executed Cargo ==> NO.0 Name.june
worker-4 executed Cargo ==> NO.0 Name.july
worker-3 executed Cargo ==> NO.1 Name.june
worker-0 executed Cargo ==> NO.1 Name.alen
worker-2 executed Cargo ==> NO.1 Name.july
worker-1 executed Cargo ==> NO.2 Name.june
worker-0 executed Cargo ==> NO.2 Name.july
worker-2 executed Cargo ==> NO.2 Name.alen
worker-3 executed Cargo ==> NO.3 Name.june
worker-4 executed Cargo ==> NO.4 Name.june
worker-2 executed Cargo ==> NO.3 Name.alen
worker-3 executed Cargo ==> NO.3 Name.july
worker-4 executed Cargo ==> NO.5 Name.june
worker-1 executed Cargo ==> NO.6 Name.june
worker-0 executed Cargo ==> NO.4 Name.alen
worker-2 executed Cargo ==> NO.7 Name.june
worker-3 executed Cargo ==> NO.5 Name.alen
worker-2 executed Cargo ==> NO.4 Name.july
worker-4 executed Cargo ==> NO.6 Name.alen
worker-0 executed Cargo ==> NO.5 Name.july
worker-2 executed Cargo ==> NO.8 Name.june
worker-3 executed Cargo ==> NO.7 Name.alen
worker-1 executed Cargo ==> NO.6 Name.july
worker-4 executed Cargo ==> NO.8 Name.alen
worker-4 executed Cargo ==> NO.9 Name.june
worker-2 executed Cargo ==> NO.10 Name.june
worker-3 executed Cargo ==> NO.9 Name.alen
worker-1 executed Cargo ==> NO.7 Name.july
worker-2 executed Cargo ==> NO.10 Name.alen
worker-4 executed Cargo ==> NO.11 Name.alen
worker-3 executed Cargo ==> NO.11 Name.june
worker-0 executed Cargo ==> NO.8 Name.july
worker-4 executed Cargo ==> NO.12 Name.alen
worker-3 executed Cargo ==> NO.12 Name.june
worker-4 executed Cargo ==> NO.13 Name.alen
worker-1 executed Cargo ==> NO.9 Name.july
worker-2 executed Cargo ==> NO.14 Name.alen
worker-0 executed Cargo ==> NO.13 Name.june
worker-4 executed Cargo ==> NO.15 Name.alen
worker-2 executed Cargo ==> NO.10 Name.july
worker-1 executed Cargo ==> NO.14 Name.june
worker-3 executed Cargo ==> NO.15 Name.june
worker-4 executed Cargo ==> NO.16 Name.alen
worker-3 executed Cargo ==> NO.11 Name.july
worker-2 executed Cargo ==> NO.12 Name.july
worker-0 executed Cargo ==> NO.16 Name.june
worker-1 executed Cargo ==> NO.17 Name.june
worker-2 executed Cargo ==> NO.18 Name.june
worker-2 executed Cargo ==> NO.17 Name.alen
worker-4 executed Cargo ==> NO.13 Name.july
worker-0 executed Cargo ==> NO.18 Name.alen
worker-0 executed Cargo ==> NO.19 Name.june
worker-3 executed Cargo ==> NO.14 Name.july
worker-1 executed Cargo ==> NO.19 Name.alen
worker-2 executed Cargo ==> NO.20 Name.june
worker-3 executed Cargo ==> NO.21 Name.june
worker-0 executed Cargo ==> NO.15 Name.july
worker-3 executed Cargo ==> NO.20 Name.alen
worker-4 executed Cargo ==> NO.21 Name.alen
worker-3 executed Cargo ==> NO.22 Name.june
worker-1 executed Cargo ==> NO.16 Name.july
worker-2 executed Cargo ==> NO.17 Name.july
worker-0 executed Cargo ==> NO.23 Name.june