Spring Framework example source code file (Log4jConfigurer.java)

This example Spring Framework source code file (Log4jConfigurer.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

classpath_url_prefix, classpath_url_prefix, file, file, filenotfoundexception, filenotfoundexception, io, log4j, log4jconfigurer, net, network, string, string, url, xml_file_extension

The Spring Framework Log4jConfigurer.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.util;

import java.io.File;
import java.io.FileNotFoundException;
import java.net.URL;

import org.apache.log4j.LogManager;
import org.apache.log4j.PropertyConfigurator;
import org.apache.log4j.xml.DOMConfigurator;

/**
 * Convenience class that features simple methods for custom log4j configuration.
 *
 * <p>Only needed for non-default log4j initialization, for example with a custom
 * config location or a refresh interval. By default, log4j will simply read its
 * configuration from a "log4j.properties" or "log4j.xml" file in the root of
 * the classpath.
 *
 * <p>For web environments, the analogous Log4jWebConfigurer class can be found
 * in the web package, reading in its configuration from context-params in
 * <code>web.xml. In a J2EE web application, log4j is usually set up
 * via Log4jConfigListener or Log4jConfigServlet, delegating to
 * Log4jWebConfigurer underneath.
 *
 * @author Juergen Hoeller
 * @since 13.03.2003
 * @see org.springframework.web.util.Log4jWebConfigurer
 * @see org.springframework.web.util.Log4jConfigListener
 * @see org.springframework.web.util.Log4jConfigServlet
 */
public abstract class Log4jConfigurer {

	/** Pseudo URL prefix for loading from the class path: "classpath:" */
	public static final String CLASSPATH_URL_PREFIX = "classpath:";

	/** Extension that indicates a log4j XML config file: ".xml" */
	public static final String XML_FILE_EXTENSION = ".xml";


	/**
	 * Initialize log4j from the given file location, with no config file refreshing.
	 * Assumes an XML file in case of a ".xml" file extension, and a properties file
	 * otherwise.
	 * @param location the location of the config file: either a "classpath:" location
	 * (e.g. "classpath:myLog4j.properties"), an absolute file URL
	 * (e.g. "file:C:/log4j.properties), or a plain absolute path in the file system
	 * (e.g. "C:/log4j.properties")
	 * @throws FileNotFoundException if the location specifies an invalid file path
	 */
	public static void initLogging(String location) throws FileNotFoundException {
		String resolvedLocation = SystemPropertyUtils.resolvePlaceholders(location);
		URL url = ResourceUtils.getURL(resolvedLocation);
		if (resolvedLocation.toLowerCase().endsWith(XML_FILE_EXTENSION)) {
			DOMConfigurator.configure(url);
		}
		else {
			PropertyConfigurator.configure(url);
		}
	}

	/**
	 * Initialize log4j from the given location, with the given refresh interval
	 * for the config file. Assumes an XML file in case of a ".xml" file extension,
	 * and a properties file otherwise.
	 * <p>Log4j's watchdog thread will asynchronously check whether the timestamp
	 * of the config file has changed, using the given interval between checks.
	 * A refresh interval of 1000 milliseconds (one second), which allows to
	 * do on-demand log level changes with immediate effect, is not unfeasible.
	 * <p>WARNING: Log4j's watchdog thread does not terminate until VM shutdown;
	 * in particular, it does not terminate on LogManager shutdown. Therefore, it is
	 * recommended to <i>not use config file refreshing in a production J2EE
	 * environment; the watchdog thread would not stop on application shutdown there.
	 * @param location the location of the config file: either a "classpath:" location
	 * (e.g. "classpath:myLog4j.properties"), an absolute file URL
	 * (e.g. "file:C:/log4j.properties), or a plain absolute path in the file system
	 * (e.g. "C:/log4j.properties")
	 * @param refreshInterval interval between config file refresh checks, in milliseconds
	 * @throws FileNotFoundException if the location specifies an invalid file path
	 */
	public static void initLogging(String location, long refreshInterval) throws FileNotFoundException {
		String resolvedLocation = SystemPropertyUtils.resolvePlaceholders(location);
		File file = ResourceUtils.getFile(resolvedLocation);
		if (!file.exists()) {
			throw new FileNotFoundException("Log4j config file [" + resolvedLocation + "] not found");
		}
		if (resolvedLocation.toLowerCase().endsWith(XML_FILE_EXTENSION)) {
			DOMConfigurator.configureAndWatch(file.getAbsolutePath(), refreshInterval);
		}
		else {
			PropertyConfigurator.configureAndWatch(file.getAbsolutePath(), refreshInterval);
		}
	}

	/**
	 * Shut down log4j, properly releasing all file locks.
	 * <p>This isn't strictly necessary, but recommended for shutting down
	 * log4j in a scenario where the host VM stays alive (for example, when
	 * shutting down an application in a J2EE environment).
	 */
	public static void shutdownLogging() {
		LogManager.shutdown();
	}

	/**
	 * Set the specified system property to the current working directory.
	 * <p>This can be used e.g. for test environments, for applications that leverage
	 * Log4jWebConfigurer's "webAppRootKey" support in a web environment.
	 * @param key system property key to use, as expected in Log4j configuration
	 * (for example: "demo.root", used as "${demo.root}/WEB-INF/demo.log")
	 * @see org.springframework.web.util.Log4jWebConfigurer
	 */
	public static void setWorkingDirSystemProperty(String key) {
		System.setProperty(key, new File("").getAbsolutePath());
	}

}