使用maven-shade-plugin时，依赖冲突怎么办？

Question

我正在使用maven-shade-plugin创建一个包含我项目所有依赖项的可执行jar。有时，这些依赖项会带来自己的依赖项，这些依赖项会与其他库的依赖项发生冲突，而maven-shade-plugin会警告我不确定在uber jar中包含哪个版本。

[WARNING] maven-shade-plugin has detected that some .class files
[WARNING] are present in two or more JARs. When this happens, only
[WARNING] one single version of the class is copied in the uberjar.
[WARNING] Usually this is not harmful and you can skeep these
[WARNING] warnings, otherwise try to manually exclude artifacts
[WARNING] based on mvn dependency:tree -Ddetail=true and the above
[WARNING] output

通常，我对此警告的回应是使用

<!-- Amazon ElastiCache Client -->
<dependency>
    <groupId>com.amazonaws</groupId>
    <artifactId>elasticache-java-cluster-client</artifactId>
    <version>1.0.61.0</version>
    <exclusions>
        <!-- this junit dependency clashes with our test-scoped one and causes integration tests to fail to run -->
        <exclusion>
            <groupId>junit</groupId>
            <artifactId>junit-dep</artifactId>
        </exclusion>
        <!-- this dependency brings in two versions of cglib that clash with one another -->
        <exclusion>
            <groupId>jmock</groupId>
            <artifactId>jmock-cglib</artifactId>
        </exclusion>
        <!-- newer versions of these dependencies come with dropwizard-core -->
        <exclusion>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
        </exclusion>
        <exclusion>
            <groupId>commons-logging</groupId>
            <artifactId>commons-logging</artifactId>
        </exclusion>
      </exclusions>
</dependency>

当我这样做时，我使用mvn依赖项：tree来确保我排除了违规依赖项的较低版本，希望最新版本是最成熟且没有错误的。

像上面这样的案例，最终有很多排除在外的情况，对这种做法提出了两个问题：

< li >在上面的示例中，为什么我必须手动排除junit和jmock？这两个依赖项都标记为< code >




Answer 1

你尝试过用DependencyConvergence规则添加maven强制插件吗？这对我来说与阴影插件结合使用效果很好。它将告诉您哪些工件引入了相同类的不同版本。它让我找到了我必须排除的东西。

        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-enforcer-plugin</artifactId>
            <executions>
                <execution>
                    <id>enforce</id>
                    <configuration>
                        <rules>
                            <DependencyConvergence/>
                        </rules>
                    </configuration>
                    <goals>
                        <goal>enforce</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>