Maven assembly plugin and Spring

Here at Mystic, we do a lot of different types of development. It’s not all web development. I found myself writing a simple document parser that takes files uploaded by automated process, processes them by adding to a database, and finishes. One of the components we used to tie everything together, the Spring Framework, it’s great for that.

Since this would be a command line app running via cron most likely, we pulled Maven and the assembly plugin from our bag-of-tricks. Simply adding something like so:

            <plugin>
              <artifactId>maven-assembly-plugin</artifactId>
              <configuration>
                  <descriptorRefs>
                    <descriptorRef>jar-with-dependencies</descriptorRef>
                  </descriptorRefs>
                  <archive>
                    <manifest>
                      <mainClass>com.your.main.class.file</mainClass>
                    </manifest>
                  </archive>
              </configuration>
            </plugin>

All was right with the world, until we ran it from the dependency included jar on the server, and BAM!

Exception in thread “main” org.springframework.beans.factory.parsing.BeanDefinitionParsingException: Configuration problem: Unable to locate Spring NamespaceHandler for XML schema namespace http://www.springframework.org/schema/context

Ouch, how frustrating, this worked in the IDE “Works on my machine ™”. After a bit of googling I realized, we were using separate dependencies for the Spring jars that we needed, and the contents of META-INF/ were getting overwritten (only a single JAR remember?). So the solution was to swap out all the separate Spring dependencies in Maven, and use the all-in-one like so:

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring</artifactId>
            <version>${spring.version}</version>
        </dependency>

Tagged as: Development, Java, Web