Does maven dependency plugin ignore dependency versions?

Question

in my opinion, the maven dependency plugin is wrong when calculating the list of dependencies.

Suppose these 3 projects:

base1:

<?xml version="1.0" encoding="UTF-8"?>                                                                                                                            
<project>
    <modelVersion>4.0.0</modelVersion>
    <groupId>mygroup</groupId>
    <artifactId>base1</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>

    <dependencies>
      <dependency>
        <groupId>commons-lang</groupId>
        <artifactId>commons-lang</artifactId>
        <version>2.3</version>
      </dependency>
    </dependencies>
</project>

base2:

<?xml version="1.0" encoding="UTF-8"?>                                                                                                                            
<project>
    <modelVersion>4.0.0</modelVersion>
    <groupId>mygroup</groupId>
    <artifactId>base2</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>

    <dependencies>
      <dependency>
        <groupId>commons-lang</groupId>
        <artifactId>commons-lang</artifactId>
        <version>2.6</version>
      </dependency>
    </dependencies>
</project>

in combination:

<?xml version="1.0" encoding="UTF-8"?>                                                                                                                            
<project>
    <modelVersion>4.0.0</modelVersion>
    <groupId>mygroup</groupId>
    <artifactId>combined</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>

    <dependencies>
      <dependency>
        <groupId>mygroup</groupId>
        <artifactId>base1</artifactId>
        <version>1.0-SNAPSHOT</version>
      </dependency>
      <dependency>
        <groupId>mygroup</groupId>
        <artifactId>base2</artifactId>
        <version>1.0-SNAPSHOT</version>
      </dependency>
    </dependencies>
</project>

Both base1 and base2 depend on commons-lang, but each in a different version! combined depending on both: base1 and base2.

When called mvn dependency:listin combined, I expect to see base1, base2 and commons-lang in versions 2.3 and 2.6, since both are used. However, the actual conclusion:

[INFO] The following files have been resolved:
[INFO]    commons-lang:commons-lang:jar:2.3:compile
[INFO]    mygroup:base1:jar:1.0-SNAPSHOT:compile
[INFO]    mygroup:base2:jar:1.0-SNAPSHOT:compile

He doesn't even use common-lang with the highest version number, but only the one he finds first.

How can i avoid this? I need all the dependencies.

Answer 1

( ):

- , . Maven 2.0 " ", , . , POM. : , Maven 2.0.8 , , Maven 2.0.9 , : .

Maven 2.3, . , mvn dependency:tree combined, , .

combined, POM, Maven :

<?xml version="1.0" encoding="UTF-8"?>
<project>
   <modelVersion>4.0.0</modelVersion>
   <groupId>mygroup</groupId>
   <artifactId>combined</artifactId>
   <version>1.0-SNAPSHOT</version>
   <packaging>jar</packaging>

   <dependencies>
     <dependency>
       <groupId>mygroup</groupId>
       <artifactId>base1</artifactId>
       <version>1.0-SNAPSHOT</version>
     </dependency>
     <dependency>
       <groupId>mygroup</groupId>
       <artifactId>base2</artifactId>
       <version>1.0-SNAPSHOT</version>
     </dependency>
     <dependency>    <!-- This will override the versions in base1 and base2 -->
       <groupId>commons-lang</groupId>
       <artifactId>commons-lang</artifactId>
       <version>2.6</version>
     </dependency>
   </dependencies>

, Maven , , .

Answer 2

Maven pom , .

, commons-lang, maven .

, , StringUtils.isEmpty() 2.3 2.6?

.

Answer 3

Maven , " ". , , :

mvn dependency:tree -Dverbose -Dincludes=commons-lang

. : https://maven.apache.org/plugins/maven-dependency-plugin/examples/resolving-conflicts-using-the-dependency-tree.html