Java tutorial
/* * Copyright 2002-2012 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 com.dianping.resource.io.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 */ 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 java.io.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><b>WARNING:</b> 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</i> 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 java.io.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()); } }