java.lang.NoClassDefFoundError：com / mongodb / XXXXXX无法修复！ （使用：MongoDB Java驱动程序，Spigot）

Question

I'm writing a plugin for Spigot/Bukkit (Minecraft) in Java and can't figure out how to fix this problem for the life of me. Although I have done a lot of programming in other languages, this is my first attempt at programming in java. I have done many google searches, looked at dozens of pages, but everything just said to do things I have already tried.

I'm using eclipse and have converted my project to and from a maven project trying all sorts of variations of installing the mongo java driver. I've tried:
- Adding dependency/s
- Adding it to the buildpath using project->properties->Java Build Path->Add External Jar
- I've done a combination of both of the above
- I've tried using mongodb-driver, mongodb-driver-core and bson together, and with mongodb-java-driver(which should just work on it's own.)
- I've tried just using mongodb-java-driver
- I've tried using many different versions of the drivers.

It doesn't matter what I do, when I export my plugin to a jar and attempt to run it on my spigot server I get the following error:

java.lang.NoClassDefFoundError: com/mongodb/MongoClientURI

Where MongoClientURI could be replaced by any mongo class I use in my code. Am I not using the driver correctly, am I missing something? What's going on?

Answer 1

So I solved my own problem in the end. Turns out spigot doesn't recognize any jar files other than spigot plugins on execution. Shading would've solved my issue but instead I did this, which also works:

1. Created a file called MANIFEST.MF within my project directory.

2. Added the following to the file:

   Manifest-Version: 1.0
   Class-Path: libs/mongo-java-driver-3.2.2.jar
   Created-By: 1.7.0_06 (Oracle Corporation)

3. Selected "Use existing manifest from workspace" in the final step of exporting my plugin.

This meant that at runtime spigot would include {plugin location}/libs/mongo-java-driver-3.2.2.jar in it's libraries.

I found my solution here: https://www.spigotmc.org/threads/solved-mongodb-help.35922/