001: /*
002: * Copyright 2002-2007 the original author or authors.
003: *
004: * Licensed under the Apache License, Version 2.0 (the "License");
005: * you may not use this file except in compliance with the License.
006: * You may obtain a copy of the License at
007: *
008: * http://www.apache.org/licenses/LICENSE-2.0
009: *
010: * Unless required by applicable law or agreed to in writing, software
011: * distributed under the License is distributed on an "AS IS" BASIS,
012: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013: * See the License for the specific language governing permissions and
014: * limitations under the License.
015: */
016:
017: package org.springframework.scheduling.concurrent;
018:
019: import java.util.concurrent.Executor;
020: import java.util.concurrent.Executors;
021: import java.util.concurrent.RejectedExecutionException;
022:
023: import org.springframework.core.task.TaskRejectedException;
024: import org.springframework.scheduling.SchedulingTaskExecutor;
025:
026: /**
027: * Adapter that takes a JDK 1.5 <code>java.util.concurrent.Executor</code> and
028: * exposes a Spring {@link org.springframework.core.task.TaskExecutor} for it.
029: *
030: * <p><b>NOTE:</b> This class implements Spring's
031: * {@link org.springframework.core.task.TaskExecutor} interface as well as the JDK 1.5
032: * {@link java.util.concurrent.Executor} interface, with the former being the primary
033: * interface, the other just serving as secondary convenience. For this reason, the
034: * exception handling follows the TaskExecutor contract rather than the Executor contract,
035: * in particular regarding the {@link org.springframework.core.task.TaskRejectedException}.
036: *
037: * <p>Note that there is a pre-built {@link ThreadPoolTaskExecutor} that allows for
038: * defining a JDK 1.5 {@link java.util.concurrent.ThreadPoolExecutor} in bean style,
039: * exposing it as a Spring {@link org.springframework.core.task.TaskExecutor} directly.
040: * This is a convenient alternative to a raw ThreadPoolExecutor definition with
041: * a separate definition of the present adapter class.
042: *
043: * @author Juergen Hoeller
044: * @since 2.0
045: * @see java.util.concurrent.Executor
046: * @see java.util.concurrent.ThreadPoolExecutor
047: * @see java.util.concurrent.Executors
048: * @see ThreadPoolTaskExecutor
049: */
050: public class ConcurrentTaskExecutor implements SchedulingTaskExecutor,
051: Executor {
052:
053: private Executor concurrentExecutor;
054:
055: /**
056: * Create a new ConcurrentTaskExecutor,
057: * using a single thread executor as default.
058: * @see java.util.concurrent.Executors#newSingleThreadExecutor()
059: */
060: public ConcurrentTaskExecutor() {
061: setConcurrentExecutor(null);
062: }
063:
064: /**
065: * Create a new ConcurrentTaskExecutor,
066: * using the given JDK 1.5 concurrent executor.
067: * @param concurrentExecutor the JDK 1.5 concurrent executor to delegate to
068: */
069: public ConcurrentTaskExecutor(Executor concurrentExecutor) {
070: setConcurrentExecutor(concurrentExecutor);
071: }
072:
073: /**
074: * Specify the JDK 1.5 concurrent executor to delegate to.
075: */
076: public void setConcurrentExecutor(Executor concurrentExecutor) {
077: this .concurrentExecutor = (concurrentExecutor != null ? concurrentExecutor
078: : Executors.newSingleThreadExecutor());
079: }
080:
081: /**
082: * Return the JDK 1.5 concurrent executor that this adapter
083: * delegates to.
084: */
085: public Executor getConcurrentExecutor() {
086: return this .concurrentExecutor;
087: }
088:
089: /**
090: * Delegates to the specified JDK 1.5 concurrent executor.
091: * @see java.util.concurrent.Executor#execute(Runnable)
092: */
093: public void execute(Runnable task) {
094: try {
095: this .concurrentExecutor.execute(task);
096: } catch (RejectedExecutionException ex) {
097: throw new TaskRejectedException("Executor ["
098: + this .concurrentExecutor
099: + "] did not accept task: " + task, ex);
100: }
101: }
102:
103: /**
104: * This task executor prefers short-lived work units.
105: */
106: public boolean prefersShortLivedTasks() {
107: return true;
108: }
109:
110: }
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