LogManager啟動主要類

LogManager

LoggerContextFactory

LogManager啟動入口是以下static代碼

static {//綁定一個LoggerContextFactory，獲取配置文件 //private static final PropertiesUtil LOG4J_PROPERTIES = new PropertiesUtil("log4j2.component.properties");//中的屬性【log4j2.loggerContextFactory】final PropertiesUtil managerProps = PropertiesUtil.getProperties();final String factoryClassName = managerProps.getStringProperty(FACTORY_PROPERTY_NAME);if (factoryClassName != null) {try { //factory = LoaderUtil.newCheckedInstanceOf(factoryClassName, LoggerContextFactory.class);} catch (final ClassNotFoundException cnfe) {LOGGER.error("Unable to locate configured LoggerContextFactory {}", factoryClassName);} catch (final Exception ex) {LOGGER.error("Unable to create configured LoggerContextFactory {}", factoryClassName, ex);}}if (factory == null) {final SortedMap<Integer, LoggerContextFactory> factories = new TreeMap<>();// note that the following initial call to ProviderUtil may block until a Provider has been installed when// running in an OSGi environment/* 通過provider實例化LoggerContextFactory對象 log4j2是通過META-INF中的log4j-provider.properties文件獲取具體的LoggerContextFactory file:/user/home/.m2/repository/org/apache/logging/log4j/log4j-core/2.8.2/log4j-core-2.8.2.jar!/META-INF/log4j-provider.propertiesLoggerContextFactory = org.apache.logging.log4j.core.impl.Log4jContextFactory Log4jAPIVersion = 2.6.0 FactoryPriority= 10因此默認的 LoggerContextFactory是Log4jContextFactory */if (ProviderUtil.hasProviders()) {for (final Provider provider : ProviderUtil.getProviders()) {final Class<? extends LoggerContextFactory> factoryClass = provider.loadLoggerContextFactory();if (factoryClass != null) {try {factories.put(provider.getPriority(), factoryClass.newInstance());} catch (final Exception e) {LOGGER.error("Unable to create class {} specified in {}", factoryClass.getName(), provider.getUrl().toString(), e);}}}if (factories.isEmpty()) {LOGGER.error("Log4j2 could not find a logging implementation. "+ "Please add log4j-core to the classpath. Using SimpleLogger to log to the console...");factory = new SimpleLoggerContextFactory();} else if (factories.size() == 1) {factory = factories.get(factories.lastKey());} else {final StringBuilder sb = new StringBuilder("Multiple logging implementations found: \n");for (final Map.Entry<Integer, LoggerContextFactory> entry : factories.entrySet()) {sb.append("Factory: ").append(entry.getValue().getClass().getName());sb.append(", Weighting: ").append(entry.getKey()).append('\n');}factory = factories.get(factories.lastKey());sb.append("Using factory: ").append(factory.getClass().getName());LOGGER.warn(sb.toString());}} else {LOGGER.error("Log4j2 could not find a logging implementation. "+ "Please add log4j-core to the classpath. Using SimpleLogger to log to the console...");factory = new SimpleLoggerContextFactory();}}}

?

配置文件解析

?

public static ConfigurationFactory getInstance() {// volatile works in Java 1.6+, so double-checked locking also works properly//noinspection DoubleCheckedLockingif (factories == null) {LOCK.lock();try {if (factories == null) {final List<ConfigurationFactory> list = new ArrayList<>(); //CONFIGURATION_FACTORY_PROPERTY = "log4j.configurationFactory";final String factoryClass = PropertiesUtil.getProperties().getStringProperty(CONFIGURATION_FACTORY_PROPERTY);if (factoryClass != null) {addFactory(list, factoryClass);}final PluginManager manager = new PluginManager(CATEGORY);manager.collectPlugins();final Map<String, PluginType<?>> plugins = manager.getPlugins();final List<Class<? extends ConfigurationFactory>> ordered = new ArrayList<>(plugins.size());for (final PluginType<?> type : plugins.values()) {try {ordered.add(type.getPluginClass().asSubclass(ConfigurationFactory.class));} catch (final Exception ex) {LOGGER.warn("Unable to add class {}", type.getPluginClass(), ex);}}Collections.sort(ordered, OrderComparator.getInstance());for (final Class<? extends ConfigurationFactory> clazz : ordered) {addFactory(list, clazz);}// see above comments about double-checked locking//noinspection NonThreadSafeLazyInitializationfactories = Collections.unmodifiableList(list);}} finally {LOCK.unlock();}}LOGGER.debug("Using configurationFactory {}", configFactory);return configFactory;} public Configuration getConfiguration(final LoggerContext loggerContext, final String name, final URI configLocation) {if (configLocation == null) { /* //CONFIGURATION_FILE_PROPERTY = "log4j.configurationFile";1、log4j.configurationFile---ConfigurationFactory */final String configLocationStr = this.substitutor.replace(PropertiesUtil.getProperties().getStringProperty(CONFIGURATION_FILE_PROPERTY));if (configLocationStr != null) {final String[] sources = configLocationStr.split(",");if (sources.length > 1) {final List<AbstractConfiguration> configs = new ArrayList<>();for (final String sourceLocation : sources) {final Configuration config = getConfiguration(loggerContext, sourceLocation.trim());if (config != null && config instanceof AbstractConfiguration) {configs.add((AbstractConfiguration) config);} else {LOGGER.error("Failed to created configuration at {}", sourceLocation);return null;}}return new CompositeConfiguration(configs);}return getConfiguration(loggerContext, configLocationStr);} /*2、log4j2-test.properties---PropertiesConfigurationFactory 3、log4j2-test.yaml/log4j2-test.yml---YAMLConfigurationFactory 4、log4j2-test.json/log4j2-test.jsn---JsonConfigurationFactory 5、log4j2-test.xml---XMLConfigurationFactory 6、log4j2.properties---PropertiesConfigurationFactory 7、log4j2.yaml/log4j2.yml---YAMLConfigurationFactory 8、log4j2.json/log4j2.jsn---JSONConfigurationFactory 9、log4j2.xml---XMLConfigurationFactory 10、console控制臺---DefaultConfiguration */for (final ConfigurationFactory factory : getFactories()) {final String[] types = factory.getSupportedTypes();if (types != null) {for (final String type : types) {if (type.equals(ALL_TYPES)) {final Configuration config = factory.getConfiguration(loggerContext, name, configLocation);if (config != null) {return config;}}}}}} else {// configLocation != nullfinal String configLocationStr = configLocation.toString();for (final ConfigurationFactory factory : getFactories()) {final String[] types = factory.getSupportedTypes();if (types != null) {for (final String type : types) {if (type.equals(ALL_TYPES) || configLocationStr.endsWith(type)) {final Configuration config = factory.getConfiguration(loggerContext, name, configLocation);if (config != null) {return config;}}}}}}Configuration config = getConfiguration(loggerContext, true, name);if (config == null) {config = getConfiguration(loggerContext, true, null);if (config == null) {config = getConfiguration(loggerContext, false, name);if (config == null) {config = getConfiguration(loggerContext, false, null);}}}if (config != null) {return config;}LOGGER.error("No Log4j 2 configuration file found. " +"Using default configuration (logging only errors to the console), " +"or user programmatically provided configurations. " +"Set system property 'log4j2.debug' " +"to show Log4j 2 internal initialization logging. " +"See https://logging.apache.org/log4j/2.x/manual/configuration.html for instructions on how to configure Log4j 2");return new DefaultConfiguration();}

?

超強干貨來襲 云風專訪：近40年碼齡，通宵達旦的技術人生

總結

以上是生活随笔為你收集整理的log4j 2.x --LogManager的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。