Spring-boot application can only be launched with spring-boot:run when forking - java -jar fails - spring-boot

Question

I have a Spring Boot web application that I cannot start when using the executable jar directly.
I am using Spring Boot 1.2.0.RELEASE, Maven 3.0.5, Java 1.7.0_72.
I have a requirement to use the hp-roman8 character set - in order to handle incoming requests from some remote legacy systems. To provide the hp-roman8 charset I use net.freeutils.jcharset in version 1.5.
The jcharset artifact is installed in my local repository
However when launching my application using java -jar the application fails to start and I get "java.nio.charset.UnsupportedCharsetException: hp-roman8" as cause.
The same error occurs if I do mvn spring-boot:run unless I configure spring-boot-maven-plugin to always fork.
With <fork>true</fork> spring-boot:run starts the application successfully and the hp-roman8 charset is available on the classpath.
However <fork>true</fork> has no effect on the created jar, so I am still unable to launch my application using java -jar - and continue to get the "java.nio.charset.UnsupportedCharsetException: hp-roman8".
The jcharset-1.5.jar is included correctly in the created executable jar file next to the rest of the dependencies in the path "lib/jcharset-1.5.jar" so I don't quite understand why it is not available on the classpath when launching the jar.
Have any of you seen similar behavior, or have any ideas as to what I could try out in order to troubleshoot or even resolve this problem?
update:
I have also tried changing the main-class to use the PropertiesLauncher instead (using the <layout>ZIP</layout> tag in the plugin configuration) - see http://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#build-tool-plugins-maven-packaging.
Afterwards I added loader.path to my application.properties. Even if I specify the absolute path to jcharset-1.5.jar I still get the UnsupportedCharsetException.
I also tried using an exploded archive but still no go.

Answer 1

You could use Maven's shade plugin rather than Spring Boot's Maven plugin. The main difference is that the shade plugin takes all of your project's dependencies and packages them directly in the jar file, i.e. it doesn't use nested jars. While this has some disadvantages, it does mean that a single class loader is used to load all of your application's classes and, therefore, JCharset is available to the application class loader.
When you're using the Shade plugin, you shouldn't use Spring Boot's starter parent. You may want to import Boot's dependency management instead.
Your pom would look something like this:
<?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>org.springframework.boot</groupId>
<artifactId>spring-boot-sample-jcharset</artifactId>
<version>0.1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<name>spring-boot-sample-jcharset</name>
<description>Spring Boot sample showing the use of JCharset in an executable jar</description>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<java.version>1.7</java.version>
</properties>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-dependencies</artifactId>
<version>1.2.1.RELEASE</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<!-- Any additional dependencies, including JCharset -->
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>2.3</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<transformers>
<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<manifestEntries>
<Main-Class>sample.jcharset.SampleJCharsetApplication</Main-Class>
</manifestEntries>
</transformer>
</transformers>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>