Spring Boot throws ClassNotFoundException with maven dependency for another project
I have a Spring Boot project with a simple implementation EnvironmentPostProcessor
:
package com.example.demo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.env.EnvironmentPostProcessor;
import org.springframework.core.env.ConfigurableEnvironment;
public class DevProfilerResolverEnvironmentPostProcessor implements EnvironmentPostProcessor {
@Override
public void postProcessEnvironment(ConfigurableEnvironment configurableEnvironment, SpringApplication springApplication) {
if (configurableEnvironment.getActiveProfiles().length == 0) {
if (System.getenv().get("OS").contains("Windows")) {
configurableEnvironment.addActiveProfile("DEV");
}
}
}
}
Also, I registered this class in sprig.factories
:
org.springframework.boot.env.EnvironmentPostProcessor = com.example.demo.DevProfilerResolverEnvironmentPostProcessor
The structure now looks like this:
Snippet from pom file:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.example</groupId>
<artifactId>demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>demo</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.4.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
I have executed with Maven:
mvn install
Now I want to use this implementation EnvironmentPostProcessor
for another Spring Boot project. So I added it to the dependencies section for the new project:
<dependency>
<groupId>com.example</groupId>
<artifactId>demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
</dependencies>
And I wrote a simple service usage:
@Service
@Profile("DEV")
public class DeveloperService {
@Scheduled(cron = "1/1 * * * * ?")
public void doWork() {
System.out.println("Developers.... ");
}
}
and enabled scheduling for main class:
@SpringBootApplication
@EnableScheduling
public class LvivBootApplication {
public static void main(String[] args) {
SpringApplication.run(LvivBootApplication.class, args);
}
}
However, after main execution, I got the following exception:
14:56:09.822 [main] ERROR org.springframework.boot.SpringApplication - Application startup failed
java.lang.IllegalArgumentException: Unable to instantiate factory class: org.springframework.boot.env.EnvironmentPostProcessor
Caused by: java.lang.ClassNotFoundException: com.example.demo.DevProfilerResolverEnvironmentPostProcessor
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
and the dependency is added to the new project:
I run it in Windows environment.
The idea is that the OS is a Windows add DEV
profile for the first project. Secondly, a service that prints on bogus console information when a profile is DEV
, and scheduling this print every second.
I can't find what I missed in this example?
DECISION:
To create projects from the first library, the jar pom
should be fixed as follows:
<!--<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<executable>true</executable>
</configuration>
</plugin>
</plugins>
</build>-->
Or simply remove this plugin from the pom file.
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Your first bank is not a library bank. This is a packaged boot jar, created by the spring boot plugin, containing the first spring boot application and all its dependencies, intended to be run, not used as a library.
If you want to use this as a library, you need to use an untangled jar file containing only the classes and project resources.
It is rather strange if the application depends on another application. You should create a library project containing only common shared classes and resources and use that as a dependency on two spring boot applications.
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I am writing because I had a similar error in similar circumstances - I was looking for a watch and the solution was very simple. I am using Eclipse for debugging - Eclipse does not use the generated jar from the Maven build - it uses its own set of build paths with, as far as I understood, the spaced classes, etc.
My Maven project that created the JAR that I included in my main POM project did not in any way declare any dependency on the main project for example. through a common parent or something else.
Eclipse doesn't seem to understand that one of the dependencies I was using in the POM was the result of another local project - somehow, although the (jar-with-dependencies) file was in the Maven cache fine, it didn't collect it to be copied to your aforementioned set of classpaths.
I needed to explicitly add it (my library project) to the main project via Project -> Properties -> Java Build Path -> Projects - adding it to the list called "Required Projects in Build Path:"
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