Questions tagged [byte-buddy]

Byte Buddy is a code generation and manipulation library for creating and modifying Java classes during the runtime of a Java application and without the help of a compiler. Byte Buddy allows the creation of arbitrary classes and is not limited to implementing interfaces for the creation of runtime proxies. Furthermore, Byte Buddy offers a convenient API for changing classes either manually, using a Java agent or during a build.

Byte Buddy is a code generation and manipulation library for creating and modifiying Java classes during the runtime of a Java application and without the help of a compiler. Other than the code generation utilities that ship with the Java Class Library, Byte Buddy allows the creation of arbitrary classes and is not limited to implementing interfaces for the creation of runtime proxies. Furthermore, Byte Buddy offers a convenient API for changing classes either manually, using a Java agent or during a build.

In order to use Byte Buddy, one does not require an understanding of Java byte code or the class file format. In contrast, Byte Buddy's API aims for code that is concise and easy to understand for everybody. Nevertheless, Byte Buddy remains fully customizable down to the possibility of defining custom byte code. Furthermore, the API was designed to be as non-intrusive as possible and as a result, Byte Buddy does not leave any trace in the classes that were created by it. For this reason, the generated classes can exist without requiring Byte Buddy on the class path. Because of this feature, Byte Buddy's mascot was chosen to be a ghost.

Byte Buddy is written in Java 6 but supports the generation of classes for any Java version. Byte Buddy is a light-weight library and only depends on the visitor API of the Java byte code parser library ASM which does itself not require any further dependencies.

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Simple After And Before Method Interceptor With Byte Buddy

In Byte Buddy tutorial at the time of this writing, everything is explained but a simple after and before method interceptor is not there as I explained below, am I missing something or tutorial is complex. (See LoggerInterceptor example gives…
John Smith
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Byte Buddy - Method Implementation.Context.Default is no bean property - creating a setter

How do I create a setter on a field using byte buddy? What is the recommended syntax? I managed to create the getter from a field (my original question here), but using the defineMethod to create a setter is throwing a Method…
Sander_M
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How can I bind constructor parameter to a instance field?

Is it possible create new final field on a class and create a constructor with parameter that is set to that final field on class instantiation? I tried several approaches and searched for answers but found no example how to do it. What I have…
Novoj
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How do you change imports with Byte Buddy?

I'd like to change the imports of a class so that they point to a different package. Byte Buddy docs don't give much info on how one can achieve this. This is what I have so far: public class ProxyPlugin implements net.bytebuddy.build.Plugin { …
Claude
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How to efficiently wrap POJO with Bytebuddy?

I want to wrap simple POJO class. The thing is I know nothing about that class beforehand, only that it's POJO with setters and getters. I want to substitute this class with my Proxyclass so that every time client calls getter or setter I would be…
swasta
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How to assign a default value to a newly defined field?

It's my first experience with ByteBuddy and I'd like to dynamically create a subclass of java.lang.Object with only one public field named myValue of type java.lang.String and a default value of "Hello World !". Unfortunately, after calling the…
Thomas Naskali
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JUnit Test framework for Javaagent Instrumentation Framework

What are the standard ways for creating unit tests for code of a Java agent and instrumentation libraries. I have created a Java agent using the Byte Buddy framework for developing a profiler on top of a web applictaion and now i wanted to write…
Vimlesh Yadav
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Method delegation with Byte Buddy

I have a problem getting a simple example working with Byte Buddy, here's my code: import static java.util.Arrays.asList; import java.util.stream.Stream; import net.bytebuddy.ByteBuddy; import…
Lev Kuznetsov
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Unable to instrument apache httpclient using javaagent for spring boot uber jar application

I'm trying to write a javaagent with Bytebuddy to intercept apache httpclient requests and I want to use this agent for spring boot application. The agent works fine when I start my test spring boot application from Idea (run the main method…
segeon
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How do I use byte buddy to create a lazy loading class?

We have a large class (100s of methods) which has an interface annotated with lazy loading guidelines. When initially loading this object and sending it to the client we do a limited load of the most frequently used and recent data. We are…
Cogman
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Java Bytecode: Customized setter/getter with byte buddy

I am trying to create a "custom" setter method for a field with byte buddy. Buddy's own mechanism allows for standard setter/getter methods to be implemented very easily, however, I am looking for an elegant way to extend the setter with some…
Nikola Veber
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How in Java to assign to fields with Byte Buddy?

I'm having difficulty understanding the documentation for Byte Buddy. To help me learn the API I would like to generate the byte code equivalent of this Java: public final class GeneratedByByteBuddy { private final int a; public…
binkley
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Caching generated classes in Byte Buddy?

I have been using CGLIB's Enhancer for a while, but considering to switch over to Byte Buddy. It's pretty basic stuff, proxy for up to a few hundred data access interfaces, created on demand. Enhancer enhancer = new…
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What is causing duplicate class definition for java.lang.ClassLoader$ByteBuddyAccessor$V1 with INJECTION strategy?

When updating to bytebuddy 1.12.22 (from 1.10.14) we have started occasionally seeing exception indicating that java.lang.ClassLoader$ByteBuddyAccessor$V1 is (already) in module java.base of loader 'bootstrap'. We have bytebuddy (shaded into one of…
Brett Okken
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How to deal with dependency conflicts using custom classloader in java properly?

I have a multimodule project called k-sdk. It has modules like ---> agent ---> core ---> api ---> integration ---> sdk where (sdk module contains core, api, integration modules and acting as a shaded jar). This jar can be imported as a dependency in…