Hi Theo, Disclaimer: I work for Immerok
When we were working on a recipe for processing Protobuf [1], we used the protoc-jar-maven-plugin and build-helper-maven-plugin to generate the classes and add them to the classpath. Perhaps that would also help you. Best regards, Martijn [1] https://docs.immerok.cloud/docs/how-to-guides/development/reading-google-protobuf-with-apache-flink/ On Mon, Nov 14, 2022 at 9:39 AM Theodor Wübker <theo.wueb...@inside-m2m.de> wrote: > Hey everyone, > > there is some use of reflection in PbFormatUtils.getDescriptor: Namely > they get the Threads ClassLoader to load a protobuf-generated class. First > of all, this appears to be a bad practice in general (refer first answer in > this > stackoverflow > <https://stackoverflow.com/questions/1771679/difference-between-threads-context-class-loader-and-normal-classloader>). > Secondly, this comes with a Drawback for me: If I generate the Java classes > from Protobuf at runtime, they are not on the class path and not by default > available for the Threads ClassLoader. This can be overcome using a hack > like this, that sets the ClassLoader for the Current Thread to an > URLClassLoader (which can be created at runtime and is then able to find > the generated classes): > > URLClassLoader newLoader = URLClassLoader.newInstance(new URL[] > {urlToProtoClasses}, this.getClass().getClassLoader()) > Thread.currentThread().setContextClassLoader(newLoader); > > However this is not a great practice either. It will probably not even > work, once there are multiple different Threads invoking > PbFormatUtils.getDescriptor. Maybe there should be a way to set the > ClassLoader for PbFormatUtils? > If anyone knows a different solution to add the generated classes to the > classpath please let me know! > > -Theo >
