Java tutorial
/* * Copyright (C) 2010 The Guava 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 * * http://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 com.google.common.util.concurrent; import static com.google.common.base.Preconditions.checkArgument; import static com.google.common.base.Preconditions.checkNotNull; import java.lang.Thread.UncaughtExceptionHandler; import java.util.Locale; import java.util.concurrent.Executors; import java.util.concurrent.ThreadFactory; import java.util.concurrent.atomic.AtomicLong; /** * A ThreadFactory builder, providing any combination of these features: * <ul> * <li> whether threads should be marked as {@linkplain Thread#setDaemon daemon} * threads * <li> a {@linkplain ThreadFactoryBuilder#setNameFormat naming format} * <li> a {@linkplain Thread#setPriority thread priority} * <li> an {@linkplain Thread#setUncaughtExceptionHandler uncaught exception * handler} * <li> a {@linkplain ThreadFactory#newThread backing thread factory} * </ul> * <p>If no backing thread factory is provided, a default backing thread factory is * used as if by calling {@code setThreadFactory(}{@link * Executors#defaultThreadFactory()}{@code )}. * * @author Kurt Alfred Kluever * @since 4.0 */ public final class ThreadFactoryBuilder { private String nameFormat = null; private Boolean daemon = null; private Integer priority = null; private UncaughtExceptionHandler uncaughtExceptionHandler = null; private ThreadFactory backingThreadFactory = null; /** * Creates a new {@link ThreadFactory} builder. */ public ThreadFactoryBuilder() { } /** * Sets the naming format to use when naming threads ({@link Thread#setName}) * which are created with this ThreadFactory. * * @param nameFormat a {@link String#format(String, Object...)}-compatible * format String, to which a unique integer (0, 1, etc.) will be supplied * as the single parameter. This integer will be unique to the built * instance of the ThreadFactory and will be assigned sequentially. For * example, {@code "rpc-pool-%d"} will generate thread names like * {@code "rpc-pool-0"}, {@code "rpc-pool-1"}, {@code "rpc-pool-2"}, etc. * @return this for the builder pattern */ public ThreadFactoryBuilder setNameFormat(String nameFormat) { String unused = format(nameFormat, 0); // fail fast if the format is bad or null this.nameFormat = nameFormat; return this; } /** * Sets daemon or not for new threads created with this ThreadFactory. * * @param daemon whether or not new Threads created with this ThreadFactory * will be daemon threads * @return this for the builder pattern */ public ThreadFactoryBuilder setDaemon(boolean daemon) { this.daemon = daemon; return this; } /** * Sets the priority for new threads created with this ThreadFactory. * * @param priority the priority for new Threads created with this * ThreadFactory * @return this for the builder pattern */ public ThreadFactoryBuilder setPriority(int priority) { // Thread#setPriority() already checks for validity. These error messages // are nicer though and will fail-fast. checkArgument(priority >= Thread.MIN_PRIORITY, "Thread priority (%s) must be >= %s", priority, Thread.MIN_PRIORITY); checkArgument(priority <= Thread.MAX_PRIORITY, "Thread priority (%s) must be <= %s", priority, Thread.MAX_PRIORITY); this.priority = priority; return this; } /** * Sets the {@link UncaughtExceptionHandler} for new threads created with this * ThreadFactory. * * @param uncaughtExceptionHandler the uncaught exception handler for new * Threads created with this ThreadFactory * @return this for the builder pattern */ public ThreadFactoryBuilder setUncaughtExceptionHandler(UncaughtExceptionHandler uncaughtExceptionHandler) { this.uncaughtExceptionHandler = checkNotNull(uncaughtExceptionHandler); return this; } /** * Sets the backing {@link ThreadFactory} for new threads created with this * ThreadFactory. Threads will be created by invoking #newThread(Runnable) on * this backing {@link ThreadFactory}. * * @param backingThreadFactory the backing {@link ThreadFactory} which will * be delegated to during thread creation. * @return this for the builder pattern * * @see MoreExecutors */ public ThreadFactoryBuilder setThreadFactory(ThreadFactory backingThreadFactory) { this.backingThreadFactory = checkNotNull(backingThreadFactory); return this; } /** * Returns a new thread factory using the options supplied during the building * process. After building, it is still possible to change the options used to * build the ThreadFactory and/or build again. State is not shared amongst * built instances. * * @return the fully constructed {@link ThreadFactory} */ public ThreadFactory build() { return build(this); } private static ThreadFactory build(ThreadFactoryBuilder builder) { final String nameFormat = builder.nameFormat; final Boolean daemon = builder.daemon; final Integer priority = builder.priority; final UncaughtExceptionHandler uncaughtExceptionHandler = builder.uncaughtExceptionHandler; final ThreadFactory backingThreadFactory = (builder.backingThreadFactory != null) ? builder.backingThreadFactory : Executors.defaultThreadFactory(); final AtomicLong count = (nameFormat != null) ? new AtomicLong(0) : null; return new ThreadFactory() { @Override public Thread newThread(Runnable runnable) { Thread thread = backingThreadFactory.newThread(runnable); if (nameFormat != null) { thread.setName(format(nameFormat, count.getAndIncrement())); } if (daemon != null) { thread.setDaemon(daemon); } if (priority != null) { thread.setPriority(priority); } if (uncaughtExceptionHandler != null) { thread.setUncaughtExceptionHandler(uncaughtExceptionHandler); } return thread; } }; } private static String format(String format, Object... args) { return String.format(Locale.ROOT, format, args); } }