slf4j找不到log4j2罐

Question

我知道使用SLF4J和Log4j2作为记录器实现应该很容易。

您只需要将jar添加到类路径中。

我原以为我是这样做的，但我现在仍在努力

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>

然后是的摘录。类路径

<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，查看lib文件夹

$ 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

但是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）

和maven-war插件

<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* 但您使用的是logj4j-slf4j18-impl，它应该与slf4j 1.8一起使用（该版本尚未发布或更改为2.0.0版，目前为alpha版本）。你需要从

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

到

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

为了使它与您在项目中使用的slf4j兼容