alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Spring Framework example source code file (ExposeInvocationInterceptor.java)

This example Spring Framework source code file (ExposeInvocationInterceptor.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

advisor, advisor, aop, check, exposeinvocationinterceptor, exposeinvocationinterceptor, illegalstateexception, instance, io, methodinvocation, methodinvocation, no, object, object, threadlocal

The Spring Framework ExposeInvocationInterceptor.java source code

/*
 * Copyright 2002-2008 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.interceptor;

import java.io.Serializable;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;

import org.springframework.aop.Advisor;
import org.springframework.aop.support.DefaultPointcutAdvisor;
import org.springframework.core.NamedThreadLocal;

/**
 * Interceptor that exposes the current {@link org.aopalliance.intercept.MethodInvocation}
 * as a thread-local object. We occasionally need to do this; for example, when a pointcut
 * (e.g. an AspectJ expression pointcut) needs to know the full invocation context.
 *
 * <p>Don't use this interceptor unless this is really necessary. Target objects should
 * not normally know about Spring AOP, as this creates a dependency on Spring API.
 * Target objects should be plain POJOs as far as possible.
 *
 * <p>If used, this interceptor will normally be the first in the interceptor chain.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 */
public class ExposeInvocationInterceptor implements MethodInterceptor, Serializable {

	/** Singleton instance of this class */
	public static final ExposeInvocationInterceptor INSTANCE = new ExposeInvocationInterceptor();

	/**
	 * Singleton advisor for this class. Use in preference to INSTANCE when using
	 * Spring AOP, as it prevents the need to create a new Advisor to wrap the instance.
	 */
	public static final Advisor ADVISOR = new DefaultPointcutAdvisor(INSTANCE) {
		public int getOrder() {
			return Integer.MIN_VALUE;
		}
		public String toString() {
			return ExposeInvocationInterceptor.class.getName() +".ADVISOR";
		}
	};

	private static final ThreadLocal invocation = new NamedThreadLocal("Current AOP method invocation");


	/**
	 * Return the AOP Alliance MethodInvocation object associated with the current invocation.
	 * @return the invocation object associated with the current invocation
	 * @throws IllegalStateException if there is no AOP invocation in progress,
	 * or if the ExposeInvocationInterceptor was not added to this interceptor chain
	 */
	public static MethodInvocation currentInvocation() throws IllegalStateException {
		MethodInvocation mi = (MethodInvocation) invocation.get();
		if (mi == null)
			throw new IllegalStateException(
					"No MethodInvocation found: Check that an AOP invocation is in progress, " +
					"and that the ExposeInvocationInterceptor is in the interceptor chain.");
		return mi;
	}


	/**
	 * Ensures that only the canonical instance can be created.
	 */
	private ExposeInvocationInterceptor() {
	}

	public Object invoke(MethodInvocation mi) throws Throwable {
		Object old = invocation.get();
		invocation.set(mi);
		try {
			return mi.proceed();
		}
		finally {
			invocation.set(old);
		}
	}
	
	/**
	 * Required to support serialization. Replaces with canonical instance
	 * on deserialization, protecting Singleton pattern.
	 * <p>Alternative to overriding the equals method.
	 */
	private Object readResolve() {
		return INSTANCE;
	}

}

Other Spring Framework examples (source code examples)

Here is a short list of links related to this Spring Framework ExposeInvocationInterceptor.java source code file:

... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.