Java tutorial
/* * Copyright 2002-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * https://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.springframework.scheduling.concurrent; import java.util.Date; import java.util.concurrent.Executor; import java.util.concurrent.Executors; import java.util.concurrent.RejectedExecutionException; import java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.ScheduledFuture; import java.util.concurrent.TimeUnit; import javax.enterprise.concurrent.LastExecution; import javax.enterprise.concurrent.ManagedScheduledExecutorService; import org.springframework.core.task.TaskRejectedException; import org.springframework.lang.Nullable; import org.springframework.scheduling.TaskScheduler; import org.springframework.scheduling.Trigger; import org.springframework.scheduling.support.SimpleTriggerContext; import org.springframework.scheduling.support.TaskUtils; import org.springframework.util.Assert; import org.springframework.util.ClassUtils; import org.springframework.util.ErrorHandler; /** * Adapter that takes a {@code java.util.concurrent.ScheduledExecutorService} and * exposes a Spring {@link org.springframework.scheduling.TaskScheduler} for it. * Extends {@link ConcurrentTaskExecutor} in order to implement the * {@link org.springframework.scheduling.SchedulingTaskExecutor} interface as well. * * <p>Autodetects a JSR-236 {@link javax.enterprise.concurrent.ManagedScheduledExecutorService} * in order to use it for trigger-based scheduling if possible, instead of Spring's * local trigger management which ends up delegating to regular delay-based scheduling * against the {@code java.util.concurrent.ScheduledExecutorService} API. For JSR-236 style * lookup in a Java EE 7 environment, consider using {@link DefaultManagedTaskScheduler}. * * <p>Note that there is a pre-built {@link ThreadPoolTaskScheduler} that allows for * defining a {@link java.util.concurrent.ScheduledThreadPoolExecutor} in bean style, * exposing it as a Spring {@link org.springframework.scheduling.TaskScheduler} directly. * This is a convenient alternative to a raw ScheduledThreadPoolExecutor definition with * a separate definition of the present adapter class. * * @author Juergen Hoeller * @author Mark Fisher * @since 3.0 * @see java.util.concurrent.ScheduledExecutorService * @see java.util.concurrent.ScheduledThreadPoolExecutor * @see java.util.concurrent.Executors * @see DefaultManagedTaskScheduler * @see ThreadPoolTaskScheduler */ public class ConcurrentTaskScheduler extends ConcurrentTaskExecutor implements TaskScheduler { @Nullable private static Class<?> managedScheduledExecutorServiceClass; static { try { managedScheduledExecutorServiceClass = ClassUtils.forName( "javax.enterprise.concurrent.ManagedScheduledExecutorService", ConcurrentTaskScheduler.class.getClassLoader()); } catch (ClassNotFoundException ex) { // JSR-236 API not available... managedScheduledExecutorServiceClass = null; } } private ScheduledExecutorService scheduledExecutor; private boolean enterpriseConcurrentScheduler = false; @Nullable private ErrorHandler errorHandler; /** * Create a new ConcurrentTaskScheduler, * using a single thread executor as default. * @see java.util.concurrent.Executors#newSingleThreadScheduledExecutor() */ public ConcurrentTaskScheduler() { super(); this.scheduledExecutor = initScheduledExecutor(null); } /** * Create a new ConcurrentTaskScheduler, using the given * {@link java.util.concurrent.ScheduledExecutorService} as shared delegate. * <p>Autodetects a JSR-236 {@link javax.enterprise.concurrent.ManagedScheduledExecutorService} * in order to use it for trigger-based scheduling if possible, * instead of Spring's local trigger management. * @param scheduledExecutor the {@link java.util.concurrent.ScheduledExecutorService} * to delegate to for {@link org.springframework.scheduling.SchedulingTaskExecutor} * as well as {@link TaskScheduler} invocations */ public ConcurrentTaskScheduler(ScheduledExecutorService scheduledExecutor) { super(scheduledExecutor); this.scheduledExecutor = initScheduledExecutor(scheduledExecutor); } /** * Create a new ConcurrentTaskScheduler, using the given {@link java.util.concurrent.Executor} * and {@link java.util.concurrent.ScheduledExecutorService} as delegates. * <p>Autodetects a JSR-236 {@link javax.enterprise.concurrent.ManagedScheduledExecutorService} * in order to use it for trigger-based scheduling if possible, * instead of Spring's local trigger management. * @param concurrentExecutor the {@link java.util.concurrent.Executor} to delegate to * for {@link org.springframework.scheduling.SchedulingTaskExecutor} invocations * @param scheduledExecutor the {@link java.util.concurrent.ScheduledExecutorService} * to delegate to for {@link TaskScheduler} invocations */ public ConcurrentTaskScheduler(Executor concurrentExecutor, ScheduledExecutorService scheduledExecutor) { super(concurrentExecutor); this.scheduledExecutor = initScheduledExecutor(scheduledExecutor); } private ScheduledExecutorService initScheduledExecutor(@Nullable ScheduledExecutorService scheduledExecutor) { if (scheduledExecutor != null) { this.scheduledExecutor = scheduledExecutor; this.enterpriseConcurrentScheduler = (managedScheduledExecutorServiceClass != null && managedScheduledExecutorServiceClass.isInstance(scheduledExecutor)); } else { this.scheduledExecutor = Executors.newSingleThreadScheduledExecutor(); this.enterpriseConcurrentScheduler = false; } return this.scheduledExecutor; } /** * Specify the {@link java.util.concurrent.ScheduledExecutorService} to delegate to. * <p>Autodetects a JSR-236 {@link javax.enterprise.concurrent.ManagedScheduledExecutorService} * in order to use it for trigger-based scheduling if possible, * instead of Spring's local trigger management. * <p>Note: This will only apply to {@link TaskScheduler} invocations. * If you want the given executor to apply to * {@link org.springframework.scheduling.SchedulingTaskExecutor} invocations * as well, pass the same executor reference to {@link #setConcurrentExecutor}. * @see #setConcurrentExecutor */ public void setScheduledExecutor(@Nullable ScheduledExecutorService scheduledExecutor) { initScheduledExecutor(scheduledExecutor); } /** * Provide an {@link ErrorHandler} strategy. */ public void setErrorHandler(ErrorHandler errorHandler) { Assert.notNull(errorHandler, "ErrorHandler must not be null"); this.errorHandler = errorHandler; } @Override @Nullable public ScheduledFuture<?> schedule(Runnable task, Trigger trigger) { try { if (this.enterpriseConcurrentScheduler) { return new EnterpriseConcurrentTriggerScheduler().schedule(decorateTask(task, true), trigger); } else { ErrorHandler errorHandler = (this.errorHandler != null ? this.errorHandler : TaskUtils.getDefaultErrorHandler(true)); return new ReschedulingRunnable(task, trigger, this.scheduledExecutor, errorHandler).schedule(); } } catch (RejectedExecutionException ex) { throw new TaskRejectedException( "Executor [" + this.scheduledExecutor + "] did not accept task: " + task, ex); } } @Override public ScheduledFuture<?> schedule(Runnable task, Date startTime) { long initialDelay = startTime.getTime() - System.currentTimeMillis(); try { return this.scheduledExecutor.schedule(decorateTask(task, false), initialDelay, TimeUnit.MILLISECONDS); } catch (RejectedExecutionException ex) { throw new TaskRejectedException( "Executor [" + this.scheduledExecutor + "] did not accept task: " + task, ex); } } @Override public ScheduledFuture<?> scheduleAtFixedRate(Runnable task, Date startTime, long period) { long initialDelay = startTime.getTime() - System.currentTimeMillis(); try { return this.scheduledExecutor.scheduleAtFixedRate(decorateTask(task, true), initialDelay, period, TimeUnit.MILLISECONDS); } catch (RejectedExecutionException ex) { throw new TaskRejectedException( "Executor [" + this.scheduledExecutor + "] did not accept task: " + task, ex); } } @Override public ScheduledFuture<?> scheduleAtFixedRate(Runnable task, long period) { try { return this.scheduledExecutor.scheduleAtFixedRate(decorateTask(task, true), 0, period, TimeUnit.MILLISECONDS); } catch (RejectedExecutionException ex) { throw new TaskRejectedException( "Executor [" + this.scheduledExecutor + "] did not accept task: " + task, ex); } } @Override public ScheduledFuture<?> scheduleWithFixedDelay(Runnable task, Date startTime, long delay) { long initialDelay = startTime.getTime() - System.currentTimeMillis(); try { return this.scheduledExecutor.scheduleWithFixedDelay(decorateTask(task, true), initialDelay, delay, TimeUnit.MILLISECONDS); } catch (RejectedExecutionException ex) { throw new TaskRejectedException( "Executor [" + this.scheduledExecutor + "] did not accept task: " + task, ex); } } @Override public ScheduledFuture<?> scheduleWithFixedDelay(Runnable task, long delay) { try { return this.scheduledExecutor.scheduleWithFixedDelay(decorateTask(task, true), 0, delay, TimeUnit.MILLISECONDS); } catch (RejectedExecutionException ex) { throw new TaskRejectedException( "Executor [" + this.scheduledExecutor + "] did not accept task: " + task, ex); } } private Runnable decorateTask(Runnable task, boolean isRepeatingTask) { Runnable result = TaskUtils.decorateTaskWithErrorHandler(task, this.errorHandler, isRepeatingTask); if (this.enterpriseConcurrentScheduler) { result = ManagedTaskBuilder.buildManagedTask(result, task.toString()); } return result; } /** * Delegate that adapts a Spring Trigger to a JSR-236 Trigger. * Separated into an inner class in order to avoid a hard dependency on the JSR-236 API. */ private class EnterpriseConcurrentTriggerScheduler { public ScheduledFuture<?> schedule(Runnable task, final Trigger trigger) { ManagedScheduledExecutorService executor = (ManagedScheduledExecutorService) scheduledExecutor; return executor.schedule(task, new javax.enterprise.concurrent.Trigger() { @Override @Nullable public Date getNextRunTime(@Nullable LastExecution le, Date taskScheduledTime) { return (trigger.nextExecutionTime(le != null ? new SimpleTriggerContext(le.getScheduledStart(), le.getRunStart(), le.getRunEnd()) : new SimpleTriggerContext())); } @Override public boolean skipRun(LastExecution lastExecution, Date scheduledRunTime) { return false; } }); } } }