Fix: JAXB + Java >= 9 Class Loader Bug & Ensure Tomcat Deployment

- Problem: Jaxb + JAVA >= 9 Runtime + Tomcat = ClassNotFoundException:
  ContextFactory.

  Reason: Apparently, jaxb uses the "wrong" classloader (the system
  classloader via the thread classloader) and this classloader does
  not know about jaxb api's and implementations at runtime since
  oracle decided to move jaxb* out of JRE.

  Solution: create a new thread, override the thread's "thread"
  classloader with the "class" classloader and do all jaxb
  interactions in that thread. See:
  https://sjhannah.com/blog/2018/11/21/jaxb-hell-on-jdk-9/

- Move "run jaxb interactions in own thread with class class loader"
  code into own component (JaxbClassNotFoundFix,
  runInTheadWithClassClassLoader) and wrap ClientFactory and
  Marshaller code into the "runInTheadWithClassClassLoader".

- Ensure that app can be deployed in a Tomcat container (by following
  this guide: https://www.baeldung.com/spring-boot-war-tomcat-deploy)

1 files changed, 10 insertions, 3 deletions

diff --git a/src/main/java/at/gv/egiz/moazs/scheme/Marshaller.java b/src/main/java/at/gv/egiz/moazs/scheme/Marshaller.java
index 1a86079..bf502c0 100644
--- a/src/main/java/at/gv/egiz/moazs/scheme/Marshaller.java
+++ b/src/main/java/at/gv/egiz/moazs/scheme/Marshaller.java
@@ -9,6 +9,8 @@ import java.io.InputStream;
 import java.io.StringWriter;
 import java.util.HashMap;
 
+import static at.gv.egiz.moazs.util.JAXBClassNotFoundFix.runInTheadWithClassClassLoader;
+
 /**
  * @author xerx593
  * Source: https://stackoverflow.com/questions/44676532/how-to-use-spring-to-marshal-and-unmarshal-xml
@@ -32,17 +34,22 @@ public class Marshaller {
     }
 
     public <T> String marshallXml(final T obj) {
+
         if (obj == null) {
             return "null";
         }
 
         StringWriter sw = new StringWriter();
         Result result = new StreamResult(sw);
-        jaxbMarshaller.marshal(obj, result);
-        return sw.toString();
+
+        return runInTheadWithClassClassLoader(() -> {
+            jaxbMarshaller.marshal(obj, result);
+            return sw.toString();
+        });
     }
 
     public <T> T unmarshallXml(final InputStream xml) {
-        return (T) jaxbMarshaller.unmarshal(new StreamSource(xml));
+        return runInTheadWithClassClassLoader(
+                () -> (T) jaxbMarshaller.unmarshal(new StreamSource(xml)));
     }
 }