Скачать или смотреть Resolving java.lang.NoClassDefFoundError While Upgrading From Hibernate 3.5 to Hibernate 5.5.x

Discover how to solve the common issues faced during the migration from Hibernate 3.5 to the latest Hibernate 5.5.x, including dependencies management and configuration updates.
---
This video is based on the question https://stackoverflow.com/q/68595382/ asked by the user 'tjholmes66' ( https://stackoverflow.com/u/1666206/ ) and on the answer https://stackoverflow.com/a/68685016/ provided by the user 'tjholmes66' ( https://stackoverflow.com/u/1666206/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Upgrade from Hibernate 3.5 to Hibernate 5.5.x Latest Issues

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Troubleshooting Hibernate Migration: From 3.5 to 5.5.x

Upgrading an application can be a daunting task, especially when dealing with dependencies and framework changes. When moving from Hibernate 3.5.6-Final to 5.5.4.Final, many developers encounter issues that can create roadblocks in their projects. One common issue is related to old class references that no longer exist in the updated version. In this guide, we will explore one such issue and provide a step-by-step guide to resolving it effectively.

The Problem: NoClassDefFoundError

During the upgrade process, our project compiles without errors, but upon running the application, the following error is encountered:

[[See Video to Reveal this Text or Code Snippet]]

This error indicates that the class org.hibernate.cache.access.AccessType from Hibernate 3.5.6 is missing in your application after the upgrade. Instead, you should now be using org.hibernate.cache.spi.access.AccessType. This case raises concerns over configuration and dependencies that need to be addressed for a successful transition.

Understanding the Cause

The root of the issue lies in the cache management setup during the upgrade. In Hibernate 3.5, the project was utilizing an older version of EhCache, which does not align with the new configurations required for Hibernate 5.5.x. Here are a couple of key points regarding this transition:

Old Dependencies: The existing ehcache-core dependency in the Maven configuration was outdated and incompatible with the new Hibernate version.

Configuration Changes: The previous Hibernate cache-related configuration no longer applies after the upgrade, necessitating changes in how the second-level cache is handled.

Steps to Resolve the Issue

1. Update Your Maven Dependencies

First, modify your pom.xml to replace the old EhCache with the updated versions that align with Hibernate 5.5.x.

Here’s an example of updated dependencies:

[[See Video to Reveal this Text or Code Snippet]]

2. Update Configuration File

The configuration for Hibernate’s second-level cache needs to be updated. Change your primary-hibernate.cfg.xml from this format:

[[See Video to Reveal this Text or Code Snippet]]

to the updated version as follows:

[[See Video to Reveal this Text or Code Snippet]]

3. Replace Old Class References

Ensure that all occurrences of net.sf.ehcache in your application code are replaced with the corresponding newer EhCache classes. This can be crucial as legacy references can lead to further problems during runtime.

4. Build and Test Your Application

Now that you’ve updated the dependencies and configuration, it is time to rebuild your project. Run the application once again and check to see if the NoClassDefFoundError is resolved.

Conclusion

Upgrading from an older version of Hibernate to the latest can present challenges, but understanding the causes of issues like java.lang.NoClassDefFoundError, and being thorough with dependency and configuration updates can ease the transition. By following the steps outlined above, you can ensure that your Java web application runs smoothly on Hibernate 5.5.x, capitalizing on the latest enhancements and fixes.

Feel free to share your experiences and any further questions regarding Hibernate upgrades in the comments below!