Jvm.NET 1.0.0

Jvm.NET

A production-grade .NET library that embeds an in-process JVM and lets you drive it from C#: launch jars with arguments, rewrite bytecode at runtime, and listen to Java method / VM events.

First stable release targeting OpenJDK 21 (LTS).

Highlights

• In-process JVM — boots libjvm.so / jvm.dll / libjvm.dylib in the current process; no java subprocess.
• Invoke anything — load jars, find classes, call static / virtual methods, run main(String[]).
• Bytecode rewriting — register IBytecodeTransformer callbacks backed by JVMTI ClassFileLoadHook / RetransformClasses / RedefineClasses. Ships with a C# port of ASM core for class file parsing and emission (supports unequal-length string replacement, constant pool rebuild).
• Event listening — subscribe to MethodEntry, MethodExit, Exception, ClassLoad, ClassPrepare, ThreadStart/End, VMInit/Death. MethodEntry/MethodExit/Exception are simulated via bytecode instrumentation (方案 B) to bypass onload-only JVMTI capability restrictions of embedded JVMs.
• Version abstraction — each JDK version lives under Abstractions/jdkXX/ and exposes a single IJvmRuntime facade, so callers don't deal with version-specific JVMTI quirks.
• Cross-platform — net8.0 / net9.0 / net10.0 on Windows, Linux and macOS.

Install

dotnet add package Jvm.NET

Quick start

using Jvm.NET;
using Jvm.NET.Abstractions;

var runtime = JvmInitializer.Initialize(new JvmInitializationOptions
{
    JdkBinPath = @"C:\jdk-21\bin",     // or /usr/lib/jvm/jdk-21/bin
    Version    = JdkVersion.Jdk21,
    Classpath  = ["/opt/myapp/app.jar"],
});

// Run the main(String[]) of a jar in-process
runtime.Invoker.RunMain("/opt/myapp/app.jar", "com.example.App", "--verbose", "input.txt");

// Listen to every method entry (via bytecode instrumentation)
runtime.EventListener.SubscribeMethodEntry(e =>
    Console.WriteLine($"-> {e.Class.Name}.{e.MethodName}"));

// Listen to exceptions thrown inside instrumented methods
runtime.EventListener.SubscribeException(e =>
    Console.WriteLine($"ex in {e.ThrowingClass?.Name}.{e.MethodName}: {e.Exception.Class.Name}"));

// Rewrite bytecode at load time
using var token = runtime.BytecodeModifier.RegisterTransformer(new MyTransformer());
runtime.BytecodeModifier.RetransformClasses([runtime.Invoker.LoadClass("com.example.App")]);

Documentation

• 中文说明
• API reference
• 中文 API 参考

License

MIT © XSY_xiaoqi