java - 为什么执行器框架中的任务是线程

Question

Executor 框架维护自己的 Workers 池，这些 Workers 只关注线程。那么，为什么我们必须传递 Thread/Runnable 作为参数。为什么没有简单的Task界面？

ExecutorService executorService = Executors.newFixedThreadPool(3); // 3 worker thread
executorService.execute(new Thread()); // why thread? Nobody is going to use this as thread?

我问这个是因为 ThreadPoolExecutor 在内部使用传递线程的 run 方法。

请引用以下 ThreadPoolExecutor 的代码摘录:

final void runWorker(Worker w) {
        Runnable task = w.firstTask;
        w.firstTask = null;
        boolean completedAbruptly = true;
        try {
            while (task != null || (task = getTask()) != null) {
                w.lock();
                clearInterruptsForTaskRun();
                try {
                    beforeExecute(w.thread, task);
                    Throwable thrown = null;
                    try {
                        task.run();
                    } catch (RuntimeException x) {
                        thrown = x; throw x;
                    } catch (Error x) {
                        thrown = x; throw x;
                    } catch (Throwable x) {
                        thrown = x; throw new Error(x);
                    } finally {
                        afterExecute(task, thrown);
                    }
                } finally {
                    task = null;
                    w.completedTasks++;
                    w.unlock();
                }
            }
            completedAbruptly = false;
        } finally {
            processWorkerExit(w, completedAbruptly);
        }
    }

如果我在这里遗漏了任何重要的内容，请告诉我。

Answer 1

Executor#execute(Runnable)接受任何 Runnable 接口(interface)和 Thread还实现了 Runnable 因此它是 execute() 方法的有效参数。

什么Oracle documentation关于执行器接口(interface)？

Executor 接口(interface)提供了一个方法，execute，旨在替代常见的线程创建惯用语。如果 r 是一个 Runnable 对象，e 是一个 Executor 对象，您可以替换

(new Thread(r)).start();

与

e.execute(r);

<小时/>

在你的情况下，内部它变成:

(new Thread(new Thread())).start();

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