java - 在类路径上发现多个绑定(bind) & 在类路径上检测到 log4j-over-slf4j.jar 和 slf4j-log4j12.jar

Question

我使用 Gradle 作为构建工具，在部署过程中我遇到了一些我在下面提到的问题。

Gradle 构建任务没有问题，但是当我在 tomcat8 上部署它时，它显示以下错误。

build.gradle 依赖文件如下:

dependencies {

    testCompile group: 'junit', name: 'junit', version: '4.12'

    compile group: 'javax.servlet', name: 'javax.servlet-api', version: '3.1.0'
    compile group: 'org.json', name: 'json', version: '20090211'

    // Apache Kafka Dependencies
    compile group: 'org.apache.kafka', name: 'kafka-clients', version: '2.0.0'
    compile group: 'org.apache.kafka', name: 'connect-json', version: '2.0.0'

    // Office365 authentication Dependencies
    compile group: 'com.microsoft.azure', name: 'adal4j', version: '1.6.0'
    runtime group: 'com.nimbusds', name: 'oauth2-oidc-sdk', version: '5.24.1'

    // Apache Hadoop HDFS Dependencies
    compile group: 'org.apache.hadoop', name: 'hadoop-hdfs', version: '2.9.1'
    compile group: 'org.apache.hadoop', name: 'hadoop-hdfs-client', version: '2.9.1'
    compile group: 'org.apache.hadoop', name: 'hadoop-common', version: '2.9.1'
    compile group: 'org.apache.hive', name: 'hive-jdbc', version: '2.3.3'

    // Spring Dependencies
    compile group: 'opensymphony', name: 'sitemesh', version: '2.4.2'
    compile group: 'org.springframework', name: 'spring-webmvc', version: '4.3.14.RELEASE'
    compile group: 'org.springframework', name: 'spring-tx', version: '4.3.14.RELEASE'

    // Mysql Connector Dependency
    compile group: 'mysql', name: 'mysql-connector-java', version: '6.0.6'

    // Apache Spark Dependencies
    compile group: 'com.databricks', name: 'spark-csv_2.11', version: '1.5.0'
    compile group: 'org.apache.spark', name: 'spark-sql_2.11', version: '2.3.0'
    compile group: 'org.apache.spark', name: 'spark-core_2.11', version: '2.3.0'
    compile group: 'com.fasterxml.jackson.module', name: 'jackson-module-scala_2.11', version: '2.8.8'

    // Apache Storm & Apache Kafka Consumer Dependencies
    compile group: 'org.apache.storm', name: 'storm-core', version: '1.2.0'
    compile group: 'org.apache.storm', name: 'storm-kafka', version: '1.2.0'
    compile group: 'org.apache.kafka', name: 'kafka_2.10', version: '0.9.0.1'

    // Elasticsearch Dependencies
    compile group: 'org.elasticsearch.client', name: 'elasticsearch-rest-high-level-client', version: '6.5.2'
    compile group: 'org.elasticsearch', name: 'elasticsearch', version: '6.5.2'
    //compile group: 'org.apache.logging.log4j', name: 'log4j-core', version: '2.11.1'
    //compile group: 'org.apache.logging.log4j', name: 'log4j-api', version: '2.11.1'
    //compile group: 'org.slf4j', name: 'slf4j-log4j12'
}   

错误信息:

SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/home/sagarjoshi/opt/tomcat-analytics/apache-tomcat-8.0.53/webapps/analytics/WEB-INF/lib/slf4j-log4j12-1.7.25.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/home/sagarjoshi/opt/tomcat-analytics/apache-tomcat-8.0.53/webapps/analytics/WEB-INF/lib/log4j-slf4j-impl-2.8.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/home/sagarjoshi/opt/tomcat-analytics/apache-tomcat-8.0.53/webapps/analytics/WEB-INF/lib/logback-classic-1.0.9.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Detected both log4j-over-slf4j.jar AND slf4j-log4j12.jar on the class path, preempting StackOverflowError. 
SLF4J: See also http://www.slf4j.org/codes.html#log4jDelegationLoop for more details.
17-Dec-2018 11:32:29.244 SEVERE [RMI TCP Connection(2)-127.0.0.1] org.apache.catalina.core.StandardContext.startInternal Error during ServletContainerInitializer processing
 javax.servlet.ServletException: Failed to instantiate WebApplicationInitializer class
    at org.springframework.web.SpringServletContainerInitializer.onStartup(SpringServletContainerInitializer.java:155)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5352)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:755)
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:731)
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:717)
    at org.apache.catalina.startup.HostConfig.manageApp(HostConfig.java:1730)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:300)
    at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
    at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
    at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:485)
    at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:434)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:300)
    at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
    at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
    at javax.management.remote.rmi.RMIConnectionImpl.doOperation(RMIConnectionImpl.java:1468)
    at javax.management.remote.rmi.RMIConnectionImpl.access$300(RMIConnectionImpl.java:76)
    at javax.management.remote.rmi.RMIConnectionImpl$PrivilegedOperation.run(RMIConnectionImpl.java:1309)
    at javax.management.remote.rmi.RMIConnectionImpl.doPrivilegedOperation(RMIConnectionImpl.java:1401)
    at javax.management.remote.rmi.RMIConnectionImpl.invoke(RMIConnectionImpl.java:829)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:357)
    at sun.rmi.transport.Transport$1.run(Transport.java:200)
    at sun.rmi.transport.Transport$1.run(Transport.java:197)
    at java.security.AccessController.doPrivileged(Native Method)
    at sun.rmi.transport.Transport.serviceCall(Transport.java:196)
    at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:573)
    at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:834)
    at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$0(TCPTransport.java:688)
    at java.security.AccessController.doPrivileged(Native Method)
    at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:687)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)

Answer 1

SLF4J API 旨在一次绑定(bind)一个且仅一个底层日志框架。如果类路径中存在多个绑定(bind)，SLF4J 将发出警告，列出这些绑定(bind)的位置。
当类路径上有多个绑定(bind)可用时，请选择一个且仅一个您希望使用的绑定(bind)，然后删除其他绑定(bind)。例如，如果您在类路径上同时具有 slf4j-simple-2.0.0-alpha2.jar 和 slf4j-nop-2.0.0-alpha2.jar 并且您希望使用 nop(无操作)绑定(bind)，则删除slf4j-simple-2.0.0-alpha2.jar 来自类路径。
SLF4J 在此警告中提供的位置列表通常提供了足够的信息来识别依赖关系，该依赖项将不需要的 SLF4J 绑定(bind)传递到您的项目中。在你项目的 pom.xml 文件中，在声明无良依赖时排除这个 SLF4J 绑定(bind)。例如，cassandra-all 版本 0.8.1 将 log4j 和 slf4j-log4j12 都声明为编译时依赖项。因此，当您在项目中包含 cassandra-all 作为依赖项时，cassandra-all 声明将导致 slf4j-log4j12.jar 和 log4j.jar 作为依赖项被拉入。如果您不想使用 log4j 作为 SLF4J 后端，您可以指示 Maven 排除这两个工件，如下所示:

<dependencies>
  <dependency>
    <groupId> org.apache.cassandra</groupId>
    <artifactId>cassandra-all</artifactId>
    <version>0.8.1</version>

    <exclusions>
      <exclusion> 
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
      </exclusion>
      <exclusion> 
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
      </exclusion>
    </exclusions> 

  </dependency>
</dependencies>