清洁罐子冲突

Question

In our project I want to remove all the potential jar conflicts that might arise during runtime. Our stack is so big, we have same jar brought in by different dependencies. Here is the problem, each dependency is bringing in different version of the same jar and causing issues, after fresh deployment.

Where do I start from ? Are there any maven plugins to resolve this ? Any help or pointers on this is much appricieated.

Answer 1

You can use the maven-enforcer-plugin as follows:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-enforcer-plugin</artifactId>
    <version>1.3.1</version>
    <configuration>
        <fail>true</fail>
        <rules>
            <dependencyConvergence/>
        </rules>
    </configuration>
    <executions>
        <execution>
            <id>enforce-dependencies</id>
            <goals>
                <goal>enforce</goal>
            </goals>
        </execution>
    </executions>
</plugin>

This will stop the build when there are conflicting dependencies.

Answer 2

A handy tool: JHades . In a nutshell, it is a tool that helps with Jar dependency Hell. In itself, it is a Jar with no dependencies, except for the JDK. It can be used to spot easy conflicts and to debug more severe issues. Example:

new JHades()
  .printClassLoaders()
  .printClasspath()
  .overlappingJarsReport()
  .multipleClassVersionsReport()
  .findClassByName("org.jhades.SomeServiceImpl")

Prints the class loader chain, jars, duplicate classes, ...