Rearranged WebAsyncTask constructor interdependencies and assertions

Issue: SPR-12457

spring-web/src/main/java/org/springframework/web/context/request/async/WebAsyncTask.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2014 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.
@@ -13,11 +13,13 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package org.springframework.web.context.request.async;
 
 import java.util.concurrent.Callable;
 
 import org.springframework.beans.factory.BeanFactory;
+import org.springframework.beans.factory.BeanFactoryAware;
 import org.springframework.core.task.AsyncTaskExecutor;
 import org.springframework.util.Assert;
 import org.springframework.web.context.request.NativeWebRequest;
@@ -26,94 +28,105 @@ import org.springframework.web.context.request.NativeWebRequest;
  * Holder for a {@link Callable}, a timeout value, and a task executor.
  *
  * @author Rossen Stoyanchev
+ * @author Juergen Hoeller
  * @since 3.2
  */
-public class WebAsyncTask<V> {
+public class WebAsyncTask<V> implements BeanFactoryAware {
 
 	private final Callable<V> callable;
 
-	private final Long timeout;
+	private Long timeout;
 
-	private final String executorName;
+	private AsyncTaskExecutor executor;
 
-	private final AsyncTaskExecutor executor;
+	private String executorName;
+
+	private BeanFactory beanFactory;
 
 	private Callable<V> timeoutCallback;
 
 	private Runnable completionCallback;
 
-	private BeanFactory beanFactory;
-
 
 	/**
 	 * Create a {@code WebAsyncTask} wrapping the given {@link Callable}.
 	 * @param callable the callable for concurrent handling
 	 */
 	public WebAsyncTask(Callable<V> callable) {
-		this(null, null, null, callable);
+		Assert.notNull(callable, "Callable must not be null");
+		this.callable = callable;
 	}
 
 	/**
 	 * Create a {@code WebAsyncTask} with a timeout value and a {@link Callable}.
-	 * @param timeout timeout value in milliseconds
+	 * @param timeout a timeout value in milliseconds
 	 * @param callable the callable for concurrent handling
 	 */
 	public WebAsyncTask(long timeout, Callable<V> callable) {
-		this(timeout, null, null, callable);
+		this(callable);
+		this.timeout = timeout;
 	}
 
 	/**
 	 * Create a {@code WebAsyncTask} with a timeout value, an executor name, and a {@link Callable}.
 	 * @param timeout timeout value in milliseconds; ignored if {@code null}
+	 * @param executorName the name of an executor bean to use
 	 * @param callable the callable for concurrent handling
 	 */
 	public WebAsyncTask(Long timeout, String executorName, Callable<V> callable) {
-		this(timeout, null, executorName, callable);
+		this(callable);
-		Assert.notNull(executor, "Executor name must not be null");
+		Assert.notNull(executorName, "Executor name must not be null");
+		this.executorName = executorName;
+		this.timeout = timeout;
 	}
 
 	/**
 	 * Create a {@code WebAsyncTask} with a timeout value, an executor instance, and a Callable.
 	 * @param timeout timeout value in milliseconds; ignored if {@code null}
+	 * @param executor the executor to use
 	 * @param callable the callable for concurrent handling
 	 */
 	public WebAsyncTask(Long timeout, AsyncTaskExecutor executor, Callable<V> callable) {
-		this(timeout, executor, null, callable);
+		this(callable);
 		Assert.notNull(executor, "Executor must not be null");
-	}
-
-	private WebAsyncTask(Long timeout, AsyncTaskExecutor executor, String executorName, Callable<V> callable) {
-		Assert.notNull(callable, "Callable must not be null");
-		this.callable = callable;
-		this.timeout = timeout;
 		this.executor = executor;
-		this.executorName = executorName;
+		this.timeout = timeout;
 	}
 
 
 	/**
-	 * Return the {@link Callable} to use for concurrent handling, never {@code null}.
+	 * Return the {@link Callable} to use for concurrent handling (never {@code null}).
 	 */
 	public Callable<?> getCallable() {
 		return this.callable;
 	}
 
 	/**
-	 * Return the timeout value in milliseconds or {@code null} if not value is set.
+	 * Return the timeout value in milliseconds, or {@code null} if no timeout is set.
 	 */
 	public Long getTimeout() {
 		return this.timeout;
 	}
 
 	/**
-	 * Return the AsyncTaskExecutor to use for concurrent handling, or {@code null}.
+	 * A {@link BeanFactory} to use for resolving an executor name.
+	 * <p>This factory reference will automatically be set when
+	 * {@code WebAsyncTask} is used within a Spring MVC controller.
+	 */
+	public void setBeanFactory(BeanFactory beanFactory) {
+		this.beanFactory = beanFactory;
+	}
+
+	/**
+	 * Return the AsyncTaskExecutor to use for concurrent handling,
+	 * or {@code null} if none specified.
 	 */
 	public AsyncTaskExecutor getExecutor() {
 		if (this.executor != null) {
 			return this.executor;
 		}
 		else if (this.executorName != null) {
-			Assert.state(this.beanFactory != null, "A BeanFactory is required to look up a task executor bean");
+			Assert.state(this.beanFactory != null, "BeanFactory is required to look up an executor bean by name");
 			return this.beanFactory.getBean(this.executorName, AsyncTaskExecutor.class);
 		}
 		else {
@@ -121,22 +134,13 @@ public class WebAsyncTask<V> {
 		}
 	}
 
-	/**
-	 * A {@link BeanFactory} to use to resolve an executor name. Applications are
-	 * not expected to have to set this property when {@code WebAsyncTask} is used in a
-	 * Spring MVC controller.
-	 */
-	public void setBeanFactory(BeanFactory beanFactory) {
-		this.beanFactory = beanFactory;
-	}
-
 
 	/**
-	 * Register code to invoke when the async request times out. This method is
+	 * Register code to invoke when the async request times out.
-	 * called from a container thread when an async request times out before the
+	 * <p>This method is called from a container thread when an async request times
-	 * {@code Callable} has completed. The callback is executed in the same
+	 * out before the {@code Callable} has completed. The callback is executed in
-	 * thread and therefore should return without blocking. It may return an
+	 * the same thread and therefore should return without blocking. It may return
-	 * alternative value to use, including an {@link Exception} or return
+	 * an alternative value to use, including an {@link Exception} or return
 	 * {@link CallableProcessingInterceptor#RESULT_NONE RESULT_NONE}.
 	 */
 	public void onTimeout(Callable<V> callback) {
@@ -144,9 +148,9 @@ public class WebAsyncTask<V> {
 	}
 
 	/**
-	 * Register code to invoke when the async request completes. This method is
+	 * Register code to invoke when the async request completes.
-	 * called from a container thread when an async request completed for any
+	 * <p>This method is called from a container thread when an async request
-	 * reason including timeout and network error.
+	 * completed for any reason, including timeout and network error.
 	 */
 	public void onCompletion(Runnable callback) {
 		this.completionCallback = callback;
@@ -154,12 +158,10 @@ public class WebAsyncTask<V> {
 
 	CallableProcessingInterceptor getInterceptor() {
 		return new CallableProcessingInterceptorAdapter() {
-
 			@Override
 			public <T> Object handleTimeout(NativeWebRequest request, Callable<T> task) throws Exception {
-				return (timeoutCallback != null) ? timeoutCallback.call() : CallableProcessingInterceptor.RESULT_NONE;
+				return (timeoutCallback != null ? timeoutCallback.call() : CallableProcessingInterceptor.RESULT_NONE);
 			}
-
 			@Override
 			public <T> void afterCompletion(NativeWebRequest request, Callable<T> task) throws Exception {
 				if (completionCallback != null) {