A Java library forruntime proxies andcompile-time generated static proxies. It started in 2015 as an internal AOP-style utility and has quietly stayed useful ever since — currently tracking JDK 26 and Maven 4.

Two ways to wrap a method call

Runtime —DynamicProxyBuilder

A fluent API around JDK dynamic proxies:

Serviceproxy=DynamicProxyBuilder.createBuilder(Service.class,newServiceImpl()).addIPreAction((original,method,args)->{// before every invocation}).addIPostAction((original,method,args)->{// after every invocation}).addSecurityRule(()->currentUserCanCall()).addMetrics().build();

You getpre/post hooks,security gates,logging,Dropwizard metrics andvirtual proxy strategies without writing a singleInvocationHandler.

Compile-time — annotation processor

Annotate your interface, the processor emits a static proxy class at build time. Zero reflection at runtime, full type-safety, JIT-friendly. You get the proxy behaviour with the performance characteristics of hand-written code.

<plugin><artifactId>maven-compiler-plugin</artifactId><configuration><annotationProcessorPaths><path><groupId>com.svenruppert</groupId><artifactId>proxybuilder</artifactId><version>00.11.01</version></path></annotationProcessorPaths></configuration></plugin>

When to reach for it

✅Security wrappers — declarative “is the current user allowed to call this method” without an AOP framework ✅Method-level metrics — counter / timer / histogram per method call without modifying the implementation ✅Lazy initialisation — virtual proxies that defer construction until first use ✅Tracing / debugging — pre/post hooks for ad-hoc instrumentation

❌ When you’re already in a Spring or Quarkus stack — use their AOP layers ❌ When you need cross-cutting concerns across non-interface classes — JDK proxies only wrap interfaces

Modules

• proxybuilder-annotations — annotations-only JAR (tiny, on consumer compile path)
• proxybuilder — implementation: runtime utilities + annotation processor
• proxybuilder-testusage — runnable usage examples and integration tests

License isEUPL-1.2. Maven coordinates on theproject site.