个人笔记Spring-boot 整合log4j2
今天我整合了log4j2到spring-boot，排了一整天的雷，记录一下。
整合过程很简单，
1，排除spring-boot原有的spring-boot-starter-logging，将log4j2的依赖引入
org.springframework.boot
spring-boot-starter-web
org.springframework.boot
spring-boot-starter-logging
org.springframework.boot
spring-boot-starter-log4j2
因为其他依赖里也会引这个，可以做个全局排除
org.springframework.boot
spring-boot-starter-logging
*
*
2，配置log4j2.xml， yml文件也可以
3，在application.yml中引入配置文件
# log4j2 日志配置
logging:
config: classpath:log4j2.xml
本以为这样直接启动就可以了，可发现启动不了了·····
报这个错
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/logging/log4j/core/appender/rolling/DirectFileRolloverStrategy
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:760)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:455)
at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:367)
at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:360)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at org.apache.logging.log4j.core.config.plugins.util.PluginRegistry.decodeCacheFiles(PluginRegistry.java:181)
at org.apache.logging.log4j.core.config.plugins.util.PluginRegistry.loadFromMainClassLoader(PluginRegistry.java:119)
at org.apache.logging.log4j.core.config.plugins.util.PluginManager.collectPlugins(PluginManager.java:132)
at org.apache.logging.log4j.core.pattern.PatternParser.
at org.apache.logging.log4j.core.pattern.PatternParser.
at org.apache.logging.log4j.core.layout.PatternLayout.createPatternParser(PatternLayout.java:209)
at org.apache.logging.log4j.core.layout.PatternLayout.createSerializer(PatternLayout.java:123)
at org.apache.logging.log4j.core.layout.PatternLayout.
at org.apache.logging.log4j.core.layout.PatternLayout.
at org.apache.logging.log4j.core.layout.PatternLayout$Builder.build(PatternLayout.java:494)
at org.apache.logging.log4j.core.config.AbstractConfiguration.setToDefault(AbstractConfiguration.java:567)
at org.apache.logging.log4j.core.config.DefaultConfiguration.
at org.apache.logging.log4j.core.LoggerContext.
at org.apache.logging.log4j.core.selector.ClassLoaderContextSelector.createContext(ClassLoaderContextSelector.java:171)
at org.apache.logging.log4j.core.selector.ClassLoaderContextSelector.locateContext(ClassLoaderContextSelector.java:145)
at org.apache.logging.log4j.core.selector.ClassLoaderContextSelector.getContext(ClassLoaderContextSelector.java:70)
at org.apache.logging.log4j.core.selector.ClassLoaderContextSelector.getContext(ClassLoaderContextSelector.java:57)
at org.apache.logging.log4j.core.impl.Log4jContextFactory.getContext(Log4jContextFactory.java:147)
at org.apache.logging.log4j.core.impl.Log4jContextFactory.getContext(Log4jContextFactory.java:45)
at org.apache.logging.log4j.LogManager.getContext(LogManager.java:194)
at org.apache.logging.log4j.spi.AbstractLoggerAdapter.getContext(AbstractLoggerAdapter.java:103)
at org.apache.logging.slf4j.Log4jLoggerFactory.getContext(Log4jLoggerFactory.java:43)
at org.apache.logging.log4j.spi.AbstractLoggerAdapter.getLogger(AbstractLoggerAdapter.java:42)
at org.apache.logging.slf4j.Log4jLoggerFactory.getLogger(Log4jLoggerFactory.java:29)
at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:358)
at org.apache.commons.logging.impl.SLF4JLogFactory.getInstance(SLF4JLogFactory.java:155)
at org.apache.commons.logging.impl.SLF4JLogFactory.getInstance(SLF4JLogFactory.java:132)
at org.apache.commons.logging.LogFactory.getLog(LogFactory.java:273)
at org.springframework.boot.SpringApplication.
at com.gwmfc.cheetah.CheetahApplication.main(CheetahApplication.java:27)
Caused by: java.lang.ClassNotFoundException: org.apache.logging.log4j.core.appender.rolling.DirectFileRolloverStrategy
at java.net.URLClassLoader$1.run(URLClassLoader.java:372)
at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:360)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 42 more
Disconnected from the target VM, address: '127.0.0.1:13969', transport: 'socket'
Process finished with exit code 1
百思不得其解，就去问了前辈，前辈推荐这个网站
https://www.findjar.com/class/com/groupbyinc/flux/common/apache/logging/log4j/core/appender/rolling/DirectFileRolloverStrategy.html
发现是差log4j-core这个依赖
然后又换了个错
"C:\Program Files\Java\jdk1.8\bin\java.exe" -agentlib:jdwp=transport=dt_socket,address=127.0.0.1:12999,suspend=y,server=n -javaagent:C:\Users\zhangjinqi\.IntelliJIdea2018.2\system\captureAgent\debugger-agent.jar=file:/C:/Users/zhangjinqi/AppData/Local/Temp/capture2882.props -Dfile.encoding=UTF-8 -classpath C:\Users\zhangjinqi\AppData\Local\Temp\classpath1497961761.jar com.gwmfc.cheetah.CheetahApplication
Connected to the target VM, address: '127.0.0.1:12999', transport: 'socket'
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
ERROR StatusLogger Log4j2 could not find a logging implementation. Please add log4j-core to the classpath. Using SimpleLogger to log to the console...
Disconnected from the target VM, address: '127.0.0.1:12999', transport: 'socket'
Exception in thread "main" java.lang.ClassCastException: org.apache.logging.log4j.simple.SimpleLoggerContext cannot be cast to org.apache.logging.log4j.core.LoggerContext
at org.springframework.boot.logging.log4j2.Log4J2LoggingSystem.getLoggerContext(Log4J2LoggingSystem.java:265)
at org.springframework.boot.logging.log4j2.Log4J2LoggingSystem.beforeInitialize(Log4J2LoggingSystem.java:132)
at org.springframework.boot.logging.LoggingApplicationListener.onApplicationStartingEvent(LoggingApplicationListener.java:230)
at org.springframework.boot.logging.LoggingApplicationListener.onApplicationEvent(LoggingApplicationListener.java:209)
at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:167)
at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139)
at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:122)
at org.springframework.boot.context.event.EventPublishingRunListener.starting(EventPublishingRunListener.java:69)
at org.springframework.boot.SpringApplicationRunListeners.starting(SpringApplicationRunListeners.java:48)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:292)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107)
at com.gwmfc.cheetah.CheetahApplication.main(CheetahApplication.java:27)
Process finished with exit code 1
网上说是需要排除这些依赖
log4j-to-slf4j-2.0.2.jar
log4j-to-slf4j-2.0.2-sources.jar
log4j-slf4j-impl-2.0.2.jar
log4j-slf4j-impl-2.0.2-sources.jar
我试了，没有任何卵用
不过是需要排除的 （次日又加上试了一遍）
次日加回的错误
后来终于找到是还差一个依赖log4j-api
项目终于正常启动了，日志文件也生成了。
可我正在沾沾自喜时，发现这生成的Druid的SQL是什么啊···
SQL呢···
又陷入了绝境·····经过一下午的冥思苦想
发现application.yml的filters配置写的是slf4j``可现在用的是log4j 就改了
SQL就正常输出了，但日志配置文件还需要修改，以保证日志文件和控制台都有SQL和参数输出
后来发现用logger.info什么输出的都不生效
因为程序用的还是slf4j的写法
private static Logger logger = LoggerFactory.getLogger(HiveService.class);
需要换成
private static Logger logger= LogManager.getLogger(LogManager.ROOT_LOGGER_NAME);
生效
2020.7.13
后来同事发现自己Druid的mybatis数据源映射失败，没报错但项目启动失败，找了好久才找到。
我觉得是自己的日志框架有问题
try {
SpringApplication.run(CheetahApplication.class, args);
} catch (Exception e) {
logger.error(e);
// System.out.println(e);
}
在启动类加这个解决