logback

logback:

官方文档：https://logback.qos.ch/manual/configuration.html

入口： private final static Logger logger = org.slf4j.LoggerFactory.getLogger(ServiceTest.class);
第一次用到的时候,会从LoggerFactory中拿一个logger

1. org.slf4j.LoggerFactory.getLogger(name) --> ILoggerFactory iLoggerFactory = getILoggerFactory();
初始化一个ILoggerFactory，初始化时会调用org.slf4j.impl.StaticLoggerBinder.getSingleton() 来实现其他日志框架与slf4j的绑定（bind）。
logback-classic-1.1.2.jar包里面就有这个类，这就是 logback 与 slf4j 绑定的方法。

2. StaticLoggerBinder.getSingleton() 会去执行初始化动作
init() --> new ContextInitializer(defaultLoggerContext).autoConfig();

ContextInitializer
加载配置文件顺序：前一个为空，则加载下一个
logback.groovy --> logback-test.xml --> logback.xml

19:02:56,446 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Could NOT find resource [logback.groovy]
19:02:56,447 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Could NOT find resource [logback-test.xml]
19:02:56,447 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Found resource [logback.xml] at [file:/E:/workspace/java-programs/sz-agent/sz-agent-server/target/classes/logback.xml]

30s重载配置:（<configuration scan="true" scanPeriod="30 seconds" debug="false">）
19:02:56,592 |-INFO in ReconfigureOnChangeFilter{invocationCounter=0} - Will scan for changes in [[E:workspacejava-programs z-agent z-agent-server argetclasseslogback.xml]] every 30 seconds.

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异步打日志要加下面标黄的配置，否则 %line 会显示成 ?

<appender name="ASYNC" class="ch.qos.logback.classic.AsyncAppender">
  <appender-ref ref="FILE" />
  <!-- add the following line -->
  <includeCallerData>true</includeCallerData>
</appender>

日志格式输出里面的参数是在 PatternLayout.java 里面设定的。
https://logback.qos.ch/manual/layouts.html#PatternLayout

1. %ex的使用 

%ex是默认加在输出格式最后的。如果 Packaging data （包信息）是打开的，那么默认加上 %xEx， 如果 Packaging data 是关闭的，默认加上的是 %ex。
Packaging data 是 jar 包版本信息，有时对查错比较有帮助。As of version 1.1.4, packaging data is disabled by default.

Packaging data 输出例子：

14:28:48.835 [btpool0-7] INFO  c.q.l.demo.prime.PrimeAction - 99 is not a valid value
java.lang.Exception: 99 is invalid
  at ch.qos.logback.demo.prime.PrimeAction.execute(PrimeAction.java:28) [classes/:na]
  at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431) [struts-1.2.9.jar:1.2.9]
  at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236) [struts-1.2.9.jar:1.2.9]
  at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432) [struts-1.2.9.jar:1.2.9]
  at javax.servlet.http.HttpServlet.service(HttpServlet.java:820) [servlet-api-2.5-6.1.12.jar:6.1.12]
  at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:502) [jetty-6.1.12.jar:6.1.12]
  at ch.qos.logback.demo.UserServletFilter.doFilter(UserServletFilter.java:44) [classes/:na]
  at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1115) [jetty-6.1.12.jar:6.1.12]
  at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:361) [jetty-6.1.12.jar:6.1.12]
  at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:417) [jetty-6.1.12.jar:6.1.12]
  at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:230) [jetty-6.1.12.jar:6.1.12]