package java.util.concurrent; /** * An object that executes submitted {@link Runnable} tasks. This * interface provides a way of decoupling task submission from the * mechanics of how each task will be run, including details of thread * use, scheduling, etc. An <tt>Executor</tt> is normally used * instead of explicitly creating threads. For example, rather than * invoking <tt>new Thread(new(RunnableTask())).start()</tt> for each * of a set of tasks, you might use: * Executor用于执行提交的Runnable任务。Executor提供了每个线程如何运行,线程的具体使用调度 机制的解耦的一种方式。一般用Executor执行线程,而不是显示地创建线程。比如 调用new Thread(new(RunnableTask())).start()执行线程任务。我们可以用以下方式执行线程: * <pre> * Executor executor = [i]anExecutor[/i]; * executor.execute(new RunnableTask1()); * executor.execute(new RunnableTask2()); * ... * </pre> * * However, the <tt>Executor</tt> interface does not strictly * require that execution be asynchronous. In the simplest case, an * executor can run the submitted task immediately in the caller's * thread: * Executor不需要严格意义上地异步执行线程。在一些简单的例子中,executor可以 立即在调用线程中,运行提交的任务。 * <pre> * class DirectExecutor implements Executor { * public void execute(Runnable r) { * r.run(); * } * }</pre> * * More typically, tasks are executed in some thread other * than the caller's thread. The executor below spawns a new thread * for each task. * 大多数情况下,任务是在一些线程中执行,而不是调用者线程。下面的执行器 为每个任务创建一个新的线程。 * <pre> * class ThreadPerTaskExecutor implements Executor { * public void execute(Runnable r) { * new Thread(r).start(); * } * }</pre> * * Many <tt>Executor</tt> implementations impose some sort of * limitation on how and when tasks are scheduled. The executor below * serializes the submission of tasks to a second executor, * illustrating a composite executor. *一些执行器用于实现任务何时如何调度,下面executor用于执行串行任务 * <pre> {@code * class SerialExecutor implements Executor { * final Queue<Runnable> tasks = new ArrayDeque<Runnable>(); * final Executor executor; * Runnable active; * * SerialExecutor(Executor executor) { * this.executor = executor; * } * * public synchronized void execute(final Runnable r) { * tasks.offer(new Runnable() { * public void run() { * try { * r.run(); * } finally { * scheduleNext(); * } * } * }); * if (active == null) { * scheduleNext(); * } * } * * protected synchronized void scheduleNext() { * if ((active = tasks.poll()) != null) { * executor.execute(active); * } * } * }}</pre> * * The <tt>Executor</tt> implementations provided in this package * implement {@link ExecutorService}, which is a more extensive * interface. The {@link ThreadPoolExecutor} class provides an * extensible thread pool implementation. The {@link Executors} class * provides convenient factory methods for these Executors. * ExecutorService提供了Executor实现,是一个广泛使用的接口。ThreadPoolExecutor为 一个可扩展线程池的实现。Executors提供了线程池执行器的便利的工厂方法。 * <p>Memory consistency effects: Actions in a thread prior to * submitting a {@code Runnable} object to an {@code Executor} * [url=package-summary.html#MemoryVisibility]<i>happen-before</i>[/url] * its execution begins, perhaps in another thread. * * @since 1.5 * @author Doug Lea */ public interface Executor { /** * Executes the given command at some time in the future. The command * may execute in a new thread, in a pooled thread, or in the calling * thread, at the discretion of the <tt>Executor</tt> implementation. * 在将来的某个时间执行给个的线程命令。这个命令也许在一个新线程中执行, 或一个池线程中,或调用线程中,或任凭Executor实现任意执行。 * @param command the runnable task * @throws RejectedExecutionException if this task cannot be * accepted for execution.如果线程必能不执行器执行,这抛出拒绝执行异常 * @throws NullPointerException if command is null */ void execute(Runnable command); }
Executor接口的定义
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转载自donald-draper.iteye.com/blog/2365625
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