java自定义线程池的原理简介

// 1.定义一个存储线程队列 
private LinkedBlockingQueue<Runnable> queue; 

// 2.定义工作线程进行线程的执行 
  class Worker extends Thread {  
    private SelfThreadPoolExecutor threadPoolExecutor; 
 
    public Worker(SelfThreadPoolExecutor poolExecutor) { 
      this.threadPoolExecutor = poolExecutor; 
    }  
    @Override 
    public void run() { 
      Runnable task; 
      while (threadPoolExecutor.receiveTask || threadPoolExecutor.queue.size() > 0) { 
        try { 
          // 有线程则取出来，否则等待 
          System.out.println("准备消费线程"); 
          task = threadPoolExecutor.queue.take(); 
          if (task != null) { 
            task.run(); 
            System.out.println("消费线程"); 
          } 
        } catch (InterruptedException e) { 
          e.printStackTrace(); 
        } 
      } 
    } 
  } 

// 3.存放工作线程的集合 
  private List<Worker> workerList;  
  // 4.线程池初始化 
  public SelfThreadPoolExecutor(int coreSize, int queueSize) { 
    if (coreSize <= 0 || queueSize <= 0) { 
      throw new IllegalArgumentException("参数不正确"); 
    } 
    this.queue = new LinkedBlockingQueue<>(queueSize); 
    // 线程安全的集合 
    this.workerList = Collections.synchronizedList(new ArrayList<>()); 
    for (int i = 0; i < coreSize; i++) { 
      Worker worker = new Worker(this); 
      worker.start(); 
      workerList.add(worker); 
    } 
  } 

// 5.非阻塞的方法接口 
  public boolean offer(Runnable task) { 
    if (receiveTask) { 
      return queue.offer(task); 
    } else { 
      return false; 
    } 
  } 
  // 6.阻塞的方法接口 
  public void put(Runnable task) { 
    try { 
      if (receiveTask) { 
        queue.put(task); 
      } 
    } catch (InterruptedException e) { 
      e.printStackTrace(); 
    } 
  } 

// 7.线程池的关闭 
  private boolean receiveTask = true;  
  public void shutdown() { 
    // 7.1.队列不再接收线程 
    receiveTask = false; 
    // 7.2.关闭处于wait或block的线程 
    for (Thread thread : workerList) { 
      if (Thread.State.BLOCKED.equals(thread.getState()) 
      || Thread.State.WAITING.equals(thread.getState()) 
      || Thread.State.TIMED_WAITING.equals(thread.getState())){ 
        thread.interrupt(); 
      } 
    } 
  } 

public static void main(String [] args){ 
    SelfThreadPoolExecutor selfThreadPoolExecutor = new SelfThreadPoolExecutor(5,10); 
    for(int i = 0;i < 20;i++){ 
      Runnable task = () ->{ 
        System.out.println("开启线程"); 
      }; 
      selfThreadPoolExecutor.put(task); 
    } 
    selfThreadPoolExecutor.shutdown(); 
  } 

准备消费线程 
准备消费线程 
准备消费线程 
准备消费线程 
准备消费线程 
开启线程 
消费线程 
准备消费线程 
开启线程 
消费线程 
准备消费线程 
开启线程 
消费线程 
准备消费线程 
。。。。。。