Spring Framework example source code file (TargetSource.java)

This example Spring Framework source code file (TargetSource.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Spring Framework tags/keywords

class, exception, exception, object, object, targetclassaware, targetclassaware, targetsource, targetsource

The Spring Framework TargetSource.java source code

/*<
 * Copyright 2002-2007 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
 *
 *      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 org.springframework.aop;

/**
 * A <code>TargetSource is used to obtain the current "target" of
 * an AOP invocation, which will be invoked via reflection if no around
 * advice chooses to end the interceptor chain itself.
 *
 * <p>If a TargetSource is "static", it will always return
 * the same target, allowing optimizations in the AOP framework. Dynamic
 * target sources can support pooling, hot swapping, etc.
 *
 * <p>Application developers don't usually need to work with
 * <code>TargetSources directly: this is an AOP framework interface.
 *
 * @author Rod Johnson
 */
public interface TargetSource extends TargetClassAware {

	/**
	 * Return the type of targets returned by this {@link TargetSource}.
	 * <p>Can return null, although certain usages of a
	 * <code>TargetSource might just work with a predetermined
	 * target class.
	 * @return the type of targets returned by this {@link TargetSource}
	 */
	Class getTargetClass();

	/**
	 * Will all calls to {@link #getTarget()} return the same object?
	 * <p>In that case, there will be no need to invoke
	 * {@link #releaseTarget(Object)}, and the AOP framework can cache
	 * the return value of {@link #getTarget()}.
	 * @return <code>true if the target is immutable
	 * @see #getTarget
	 */
	boolean isStatic();

	/**
	 * Return a target instance. Invoked immediately before the
	 * AOP framework calls the "target" of an AOP method invocation.
	 * @return the target object, which contains the joinpoint
	 * @throws Exception if the target object can't be resolved
	 */
	Object getTarget() throws Exception;

	/**
	 * Release the given target object obtained from the
	 * {@link #getTarget()} method.
	 * @param target object obtained from a call to {@link #getTarget()}
	 * @throws Exception if the object can't be released
	 */
	void releaseTarget(Object target) throws Exception;

}