Several useful cases for maven plugin “dependency”

The maven dependency plugin is very handy when trying to deal with following questions:

• What are the external artifacts involved in a maven project. (dependency:resolve)
• Find out how an artifact is introduced into a project. (dependency:tree)
• In a multi modules project, how these modules denpend on each other? (dependency:tree –Dincludes=com.mypackage.*)
• Find out unnecessary dependencies in a maven project. (dependency:analyze)

To solve these puzzles, we need to know some typical usage of maven dependency plugin.

1. goal ‘resolve’

#list all dependencis
mvn dependency:resolve 

Output looks like below.

2. goal ‘tree’

# list dependencies tree. 
# can use –Dincludes=[groupId]:[artifactId]:[type]:[version], can use wildcard *

# e.g  -Dincludes=org.springframework*,org.apache*    # list only package from spring and apache.

mvn dependency:tree  -Dincludes=org.springframework*

Output looks like below.

3. goal ‘analyze’

# List possible inmproper dependency. 
# 1.avoid ‘Used undeclared dependencies`
# 2.'Unused declared dependencies` are not 100% reliable, cause of <provide> or <optional>
#    need to check manually

mvn dependency:analyze

Output looks like below.

In above screenshot there are several suspicious dependencis may not be used at all. Then use “dependency:tree –Dincludes= org.springframework.boot:spring-boot-starter-web” to see how this dependency is introduced to the project.