Apache Log4j 2.2 发布，此版本是第五个 GA 版本，包括一些 bug 修复和新特性。
新特性： o LOG4J2-941: Allow JSON layout to create one compact log record per line. Thanks to Konstantinos
Liakos.
o LOG4J2-933: HTML layout should not use attribute minimalization for hr noshade. Thanks
to ppiman at gmail.com <http://gmail.com/>.
o LOG4J2-895: Specify the SyslogAppender connect timeout value as part of the configuration.
The SyslogAppender takes a new parameter connectTimeoutMillis.
o LOG4J2-899: Specify the SocketAppender connect timeout value as part of the configuration.
The SyslogAppender takes a new parameter connectTimeoutMillis.
Bugs 修复： o LOG4J2-938: (JMX) To avoid memory leaks when web applications are restarted, JMX notifications
are sent from
the caller thread in web applications. For non-web applications notifications are
sent from a background thread
as before. Thanks to Mauro Molinari.
o LOG4J2-957: Missing toUpperCase("Locale.ENGLISH"). Thanks to fatih guleryuz.
o LOG4J2-956: Manual refers to Route "AppenderRef" attribute, should be "ref". Thanks to
David Kellerman.
o LOG4J2-944: Log4j Flume appender is not adding millisecond to the event headers when the
event is logged at 000 milliseconds. Thanks to Vinayaka Ramachandra.
o LOG4J2-924: Log4j 1.2 Bridge doesn't map level ALL correctly in Category.getEffectiveLevel().
Thanks to Ryan Rupp.
o LOG4J2-931: ConsoleAppender is missing @PluginFactory annotation at createAppender method.
Thanks to Robert Gacki.
o LOG4J2-919: Logging system fails to initialize if XInclude API is not available. Thanks
to David Johle.
o LOG4J2-914: ThrowableProxy.getExtendedStackTraceAsString causes NullpointerException. Thanks
to Kaj Bjurman.
o LOG4J2-912: XML configuration does not report full error message for XInclude parser configuration
problems.
o LOG4J2-903: ClassLoaderContextSelector uses ClassLoader.toString() as a key Thanks to Mauro
Molinari.
o LOG4J2-834: ThrowableProxy throws NoClassDefFoundError. Thanks to Nikita Koval, Leonard
Broman, Thiago Kronig.
o LOG4J2-893: NullPointerException on filter when mapping JUL to Log4j2.
o LOG4J2-892: JUL adapter does not map Log4j'2 FATAL level to a JUL level.
o LOG4J2-881: AbstractLifecycle should not implement equals() and hashCode(). Thanks to Mariano
Gonzalez.
o LOG4J2-897: Javadoc for org.apache.log4j.BasicConfigurator.configure() is incorrect.
o LOG4J2-891: AbstractLifecycle should not implement equals() and hashCode().
o LOG4J2-946: [docs] Using Log4j 2 in Web Applications: Update example (Log4jWebLifeCycle
is not visible). Thanks to artemonster.
功能改进： o LOG4J2-955: Documentation: clarify system properties to control status logger, improve
troubleshooting FAQ entry.
o LOG4J2-950: Incorrect attribute name in PropertiesRewritePolicy example. Thanks to Joel
Edwards.
o LOG4J2-901: Update docs for SyslogAppender: "No structured id name was supplied" Thanks
to Tihomir Meščić, Siegfried Greisinger.
o LOG4J2-958: Update from Jackson 2.5.0 to 2.5.1.
o LOG4J2-925: Update from Jackson 2.4.4 to 2.5.0.
o LOG4J2-910: Update Jackson from 2.4.3 to 2.4.4.
o LOG4J2-881: Update Jackson from 2.4.2 to 2.4.3.
o LOG4J2-882: Update maven-core from 3.1.0 to 3.2.3.
o LOG4J2-883: Update tests from org.apache.felix.framework 4.2.1 to 4.4.1.
o LOG4J2-884: Update org.eclipse.osgi from 3.6.0 to 3.7.1.
o LOG4J2-900: Update Apache Flume from 1.5.0.1 to 1.5.2.
Apache Log4j 2.2 最低要求 Java 6，以后的版本要求 Java 7。
更多改进内容请看发行说明。
Log4j是Apache的一个开放源代码项目，通过使用Log4j，我们可以控制日志信息输送的目的地是控制台、文件、GUI组件、甚至是套接口
服务 器、NT的事件记录器、UNIX
Syslog守护进程等;我们也可以控制每一条日志的输出格式;通过定义每一条日志信息的级别，我们能够更加细致地控制日志的生成过程。最令人感兴趣的就
是，这些可以通过一个配置文件来灵活地进行配置，而不需要修改应用的代码。 在线Javadoc：http://www.ostools.net/apidocs/apidoc?api=log4j-1.2.16 | 
