log4j未创建日志文件夹打印日志

清疚 2022-08-28 15:39 266阅读 0赞

公司老旧项目进行改造，改造完未创建日志文件夹和日志文件；  
首先使用命令java -jar xxx.jar直接显示启动日志，打印日志如下

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.

经排查：使用maven-shade-plugin或者maven-assembly-plugin插件把项目打成一个可执行JAR包时会出现这个问题；  
解决方法：

<plugin>
    			<artifactId>maven-shade-plugin</artifactId>
    			<version>3.0.0</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>  <transformers> <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer"> <mainClass>com.dayunmotor.tbox.gateway.business.MainService</mainClass> </transformer> <transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer"> <resource>META-INF/spring.handlers</resource> </transformer> <transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer"> <resource>META-INF/spring.schemas</resource> </transformer> <transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer"> <resource>META-INF/spring.tooling</resource> </transformer> <transformer implementation="org.apache.maven.plugins.shade.resource.ComponentsXmlResourceTransformer"/> <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>

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。

解决这个问题就是当所有jar包被打成一个jar包时，需要对各个jar包中的Log4j2Plugins.dat进行合并，这就是maven-shade-plugin.log4j2-cachefile-transformer这个包所做的事情了。