jar2dll/jartodll

中文文档 · License · Contributing

jar2dll packages a Java JAR, optional native libraries, and startup metadata inside a Windows DLL. Loading that DLL in a JVM defines the packaged classes and invokes a configured static entry method.

Status: Windows-focused. Stable packaging is the default. The in-memory native loader is experimental and currently supports x64 PE32+ modules only.

Features

• Build a Windows DLL from a JAR and invoke a @DllMain method or Java main.
• Bundle additional Java JARs, argument files, and JVM options.
• Embed native DLLs in stable ZIP or experimental in-memory (N2DM) mode.
• Inspect metadata, recover dump-enabled JARs, and run a generic smoke runner.
• Use the WPF GUI or the j2d.exe command-line builder.

Quick start

Requirements: Windows, Visual Studio C++ Build Tools/MSBuild, and a JDK whose architecture matches the native target. Set JAVA_HOME before building.

package-builder.bat
dist\builder\j2d.exe -i "app.jar" -run com.example.Main -o "app.dll"

For local development, the legacy-compatible PowerShell entry point remains available:

.\build.ps1 -i app.jar -run com.example.Main -o build\app.dll

Repository layout

Path	Purpose
cpp/maindll/	Native JNI bootstrap DLL and in-memory PE mapper.
cpp/jni-tests/	CMake native/JNI regression fixtures and integration tests.
csharp/builder/	j2d.exe command-line builder.
csharp/gui/	WPF desktop GUI.
java/readBytesJar/	JAR tools and ASM memory-load rewriter.
java/gradle-library/	Gradle plugin and annotations.
java/Test/	Java/JNI example and test fixtures.
docs/	Architecture, build, and release documentation.
tools/	Small helper scripts used by development workflows.

Generated directories such as dist/, build/, Temp/, and language-specific bin/, obj/, .gradle/ output are intentionally ignored by Git.

Native modes

-native-mode stable is the default: explicitly supplied native libraries are stored in a ZIP bundle and extracted by the normal loader flow.

-native-mode memory embeds native modules in META-INF/jar2dll/memory-modules.n2dm. It targets x64 only and supports PE32+, normal imports, delay-load imports, and memory-to-memory native dependencies.

j2d.exe -i "app.jar" -run com.example.Main -native-mode memory ^
  -native-lib "native\example64.dll" -o "app.dll"

Read the architecture guide for the exact memory-mode load rewriting rules and limitations.

CLI reference

j2d.exe -inspect "app.dll"
j2d.exe -inspect "app.dll" -detail
j2d.exe -dump "app.dll" -o "recovered.jar"
j2d.exe -dump-config "app.dll" -o "app.dll.json"
j2d.exe -run "app.dll"

-run is a recovery/smoke runner. It does not recreate an application's own launcher environment, assets, authentication, or launcher arguments.

Development

• Build guide
• Architecture and memory mode
• Release checklist
• Contributing guide
• Security policy

License

The project source is licensed under the GNU GPL v3.0 only. This means distributed modified versions and derivative works must also be provided under GPLv3 with their corresponding source code. See THIRD_PARTY_NOTICES.md for bundled and build-time third-party components.