slf4j does not find log4j2 jars

Question

我知道将SLF4J与Log4j2一起用作记录器实现应该很容易。

您只需要将jar添加到类路径中。

我本以为我这么做了，但我仍然得到

INFO: At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned but no TLDs were found in them. Skipping unneeded JARs during scanning can improve startup time and JSP compilation time.
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.

我的pom.xml的关键部分

<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.30</version>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-slf4j18-impl</artifactId>
<version>2.14.0</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-api</artifactId>
<version>2.14.0</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-core</artifactId>
<version>2.14.0</version>
<scope>runtime</scope>
</dependency>

然后摘录.classpath

<classpathentry kind="var" path="M2_REPO/org/slf4j/slf4j-api/1.7.30/slf4j-api-1.7.30.jar" sourcepath="M2_REPO/org/slf4j/slf4j-api/1.7.30/slf4j-api-1.7.30-sources.jar"/>
<classpathentry kind="var" path="M2_REPO/org/apache/logging/log4j/log4j-slf4j18-impl/2.14.0/log4j-slf4j18-impl-2.14.0.jar" sourcepath="M2_REPO/org/apache/logging/log4j/log4j-slf4j18-impl/2.14.0/log4j-slf4j18-impl-2.14.0-sources.jar"/>
<classpathentry kind="var" path="M2_REPO/org/apache/logging/log4j/log4j-api/2.14.0/log4j-api-2.14.0.jar" sourcepath="M2_REPO/org/apache/logging/log4j/log4j-api/2.14.0/log4j-api-2.14.0-sources.jar"/>
<classpathentry kind="var" path="M2_REPO/org/apache/logging/log4j/log4j-core/2.14.0/log4j-core-2.14.0.jar" sourcepath="M2_REPO/org/apache/logging/log4j/log4j-core/2.14.0/log4j-core-2.14.0-sources.jar"/>

然后，在lib文件夹中查找

$ find ./ -name "*slf4*.jar"
./target/my-app-0.0.1-SNAPSHOT/WEB-INF/lib/log4j-slf4j18-impl-2.14.0.jar
./target/my-app-0.0.1-SNAPSHOT/WEB-INF/lib/slf4j-api-1.7.30.jar
$ find ./ -name "*log4j*.jar"
./target/my-app-0.0.1-SNAPSHOT/WEB-INF/lib/log4j-slf4j18-impl-2.14.0.jar
./target/my-app-0.0.1-SNAPSHOT/WEB-INF/lib/log4j-api-2.14.0.jar
./target/my-app-0.0.1-SNAPSHOT/WEB-INF/lib/log4j-core-2.14.0.jar

我错过了什么

我需要添加一个log4j2-config.xml文件吗？但我没有得到相应的错误消息。

我正在使用

• Eclipse版本：2020-09(4.17.0(
• Apache Maven 3.6.3

和maven-war-plugin

<plugin>
<artifactId>maven-war-plugin</artifactId>
<version>3.2.3</version>
<configuration>
<warSourceDirectory>WebContent</warSourceDirectory>
<!-- https://stackoverflow.com/a/33390519/2092322 annotations instead of web.xml -->
<failOnMissingWebXml>false</failOnMissingWebXml>
</configuration>
</plugin>

Answer 1

这是因为您使用的是slf4j 1.7.*，但使用的是假设与slf4j 1.8一起使用的logj4j-slf4j18-impl(该版本尚未发布或更改为2.0.0版本，目前为alpha版本(。您需要从更改

<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-slf4j18-impl</artifactId>
<version>2.14.0</version>
<scope>runtime</scope>
</dependency>

至

<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-slf4j-impl</artifactId>
<version>2.14.0</version>
<scope>runtime</scope>
</dependency>

为了使其与您在项目中使用的slf4j兼容