log4j2项目打成jar包运行日志无法打印
maven项目中因为引入的有log4j2 在打成jar包 通过java -cp 命令运行时,引起下面这段错误,后果就是log日志无法打印。
ERROR StatusLogger Unrecognized format specifier [d] ERROR StatusLogger Unrecognized conversion specifier [d] starting at position 16 in conversion pattern. ERROR StatusLogger Unrecognized format specifier [thread] ERROR StatusLogger Unrecognized conversion specifier [thread] starting at position 25 in conversion pattern. ERROR StatusLogger Unrecognized format specifier [level] ERROR StatusLogger Unrecognized conversion specifier [level] starting at position 35 in conversion pattern. ERROR StatusLogger Unrecognized format specifier [logger] ERROR StatusLogger Unrecognized conversion specifier [logger] starting at position 47 in conversion pattern. ERROR StatusLogger Unrecognized format specifier [msg] ERROR StatusLogger Unrecognized conversion specifier [msg] starting at position 54 in conversion pattern. ERROR StatusLogger Unrecognized format specifier [n] ERROR StatusLogger Unrecognized conversion specifier [n] starting at position 56 in conversion pattern. ERROR StatusLogger Reconfiguration failed: No configuration found for ‘5c647e05‘ at ‘null‘ in ‘null‘
先分析原因:
log4j2 是采用的插件式编程,当log4j2包编译时,或者含有log4j2插件的包编译时,会将需要加载的插件信息放在META-INF/org/apache/logging/log4j/core/config/plugins/Log4j2Plugins.dat这个文件中(包括官方logj42的原生插件),然后项目启动的时候,log4j2会在各个jar包的META-INF目录下扫描这个插件信息文件,然后去加载插件。但是当项目被打成一个jar包时,如果两个不同的jar包中都有Log4j2Plugins.dat 这个文件,就会出现问题,其中一个文件会被另一个覆盖,导致项目启动的时候有一个文件中的插件不能被正常加载,导致报错。
所以解决办法有两种,第一种是在项目编译打包时排除这个文件,第二种是合并这些文件。
我在尝试第二种时该问题还是没能解决,但是用第一种就解决了。
下面分别说下两种解决办法:
一:
在打包插件中maven-shade-plugin 排除相关这个Log4j2Plugins.dat即可
**/Log4j2Plugins.dat
<plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-shade-plugin</artifactId> <version>3.0.0</version> <configuration> <filters> <filter> <artifact>*:*</artifact> <excludes> <exclude>META-INF/*.SF</exclude> <exclude>META-INF/*.DSA</exclude> <exclude>META-INF/*.RSA</exclude> <!-- 排除log4j2插件文件 解决在打成jar包运行时日志无法打印的问题 https://stackoverflow.com/questions/34945438/log4j2-configuration-not-found-when-running-standalone-application-built-by-shad--> <exclude>**/Log4j2Plugins.dat</exclude> </excludes> </filter> </filters> <artifactSet> <includes> <include>*:*</include> </includes> </artifactSet> </configuration> <executions> <execution> <phase>package</phase> <goals> <goal>shade</goal> </goals> </execution> </executions> </plugin>
二:添加个transformer合并Log4j2Plugins.dat文件即可,需要一个第三方的转换器maven-shade-plugin.log4j2-cachefile-transformer 。本人在尝试该方法时还是未能解决以上问题,估计是哪里没配置好,该方法不行的话,建议使用第一种,简单方便。
<plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-shade-plugin</artifactId> <version>2.4.3</version> <executions> <execution> <phase>package</phase> <goals> <goal>shade</goal> </goals> <configuration> <filters> <filter> <artifact>*:*</artifact> <excludes> <exclude>META-INF/*.SF</exclude> <exclude>META-INF/*.DSA</exclude> <exclude>META-INF/*.RSA</exclude> </excludes> </filter> </filters> <finalName>${artifactId}-${env}-${version}</finalName> <transformers> <transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer"/> <transformer implementation="com.github.edwgiz.mavenShadePlugin.log4j2CacheTransformer.PluginsCacheFileTransformer" /> </transformers> </configuration> </execution> </executions> <dependencies> <dependency> <groupId>com.github.edwgiz</groupId> <artifactId>maven-shade-plugin.log4j2-cachefile-transformer</artifactId> <version>2.6.1</version> </dependency> </dependencies> </plugin>