解决maven项目中的多个SLF4J绑定 [英] Resolve multiple SLF4J bindings in maven project

问题描述

这是一个问题，听起来像是一些类似的问题在SE网站上，所以我应该是详细地说明我的问题。所以，这里是项目的最小 pom.xml ：

This is a question sounds like bunch of similar questions on SE sites, so I should be quite verbose to make my question clear. So, here is project's minimal pom.xml:

<dependencies>
     <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-classic</artifactId>
        <version>1.0.6</version>
    </dependency>

   <dependency>
        <groupId>org.codehaus.gmaven.runtime</groupId>
        <artifactId>gmaven-runtime-1.7</artifactId>
        <version>1.3</version>
   </dependency>

</dependencies>
<build>
    <plugins>
        <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>exec-maven-plugin</artifactId>
            <version>1.2.1</version>
            <configuration>
                <mainClass>org.shabunc.App</mainClass>
            </configuration>
        </plugin>
    </plugins>
</build>

这是maven生成的依赖关系树。

Here is the dependency tree produced by maven.

mvn依赖关系：tree -Dverbose -Dincludes = org.slf4j ：

[INFO] [dependency:tree {execution: default-cli}]
[INFO] org.shabunc:logdebug:jar:1.0-SNAPSHOT
[INFO] \- ch.qos.logback:logback-classic:jar:1.0.6:compile
[INFO]    \- org.slf4j:slf4j-api:jar:1.6.5:compile

现在，我们再次删除排除并检查依赖项。我们会得到：

Now, let's remove exclusion and check dependencies again. We'll get:

 [INFO] org.shabunc:logdebug:jar:1.0-SNAPSHOT
[INFO] +- ch.qos.logback:logback-classic:jar:1.0.6:compile
[INFO] |  \- org.slf4j:slf4j-api:jar:1.6.5:compile
[INFO] \- org.codehaus.gmaven.runtime:gmaven-runtime-1.7:jar:1.3:compile
[INFO]    +- (org.slf4j:slf4j-api:jar:1.5.10:compile - omitted for conflict with 1.6.5)
[INFO]    +- org.codehaus.gmaven.feature:gmaven-feature-support:jar:1.3:compile
[INFO]    |  \- (org.slf4j:slf4j-api:jar:1.5.10:compile - omitted for conflict with 1.6.5)
[INFO]    \- org.codehaus.gmaven.runtime:gmaven-runtime-support:jar:1.3:compile
[INFO]       +- (org.slf4j:slf4j-api:jar:1.5.10:compile - omitted for conflict with 1.6.5)
[INFO]       \- org.sonatype.gshell:gshell-io:jar:2.0:compile
[INFO]          \- org.sonatype.gossip:gossip:jar:1.0:compile
[INFO]             \- (org.slf4j:slf4j-api:jar:1.5.8:compile - omitted for conflict with 1.6.5)

所以，我们可以看到，一切都按预期运行，而冲突的依赖关系实际上被排除在外。但事实是，即使依赖关系 ，我仍然会收到以下消息，同时编译和调用 mvn exec：java ：

So, as we can see, everything works as expected, and conflicting dependency is actually get excluded. But the thing is that even with dependency excluded I still get following message while compiling and calling mvn exec:java:

SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/home/shabunc/.m2/repository/ch/qos/logback/logback-classic/1.0.6/logback-classic-1.0.6.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/home/shabunc/.m2/repository/org/sonatype/gossip/gossip/1.0/gossip-1.0.jar!/org/slf4j/impl/StaticLoggerBinder.class]

问题是：为什么我仍然看到这个警告在执行过程中只能使一个版本的slf4j可以达到什么呢？

The question is: Why I still see this warning and what exactly should be done to make only one version of slf4j reachable during execution?

推荐答案

你的问题没有得到两个副本SLF4J API，它得到两个不同的SLF4J实现。你需要排除Gossip，而不是API。这意味着：

Your problem isn't getting two copies of the SLF4J API, it's getting two different SLF4J implementations. You need to exclude Gossip, not the API. That means something like:

<dependency>
    <groupId>org.codehaus.gmaven.runtime</groupId>
    <artifactId>gmaven-runtime-1.7</artifactId>
    <version>1.3</version>
    <exclusions>
      <exclusion>
        <groupId>org.sonatype.gossip</groupId>
        <artifactId>gossip</artifactId>
      </exclusion>
    </exclusions>
</dependency>

Gossip依赖关系由 gshell-io ;希望实际上并不需要Gossip，它只需要一个SLF4J SLF4J，您将以Logback的形式提供。

The Gossip dependency is declared by gshell-io; hopefully, it doesn't actually need Gossip, it just needs an SLF4J SLF4J, which you are supplying in the shape of Logback.

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