jar-explorer

name	jar-explorer
description	Explore contents of JAR files and decompile Java class files. Use when you need to understand the internal structure of a JAR, view its manifest, or read the source code of a compiled .class file.

JAR Explorer Skill

This skill provides tools and procedures for exploring Java Archive (JAR) files and decompiling their contents into readable Java source code.

Key Features

1. List JAR Contents: Enumerate all files and directories inside a JAR.
2. View Manifest: Extract and display the META-INF/MANIFEST.MF file.
3. Decompile Class Files: Convert .class files back to .java source code using the bundled CFR decompiler.
4. Extract Resources: Extract any file from the JAR to the local filesystem.

Workflows

1. List Contents of a JAR

To see what's inside a JAR file, use the jar_explorer.py script:

python3 scripts/jar_explorer.py list <path_to_jar>

2. View the Manifest

The manifest file often contains metadata like the version and main class:

python3 scripts/jar_explorer.py manifest <path_to_jar>

3. Decompile a Class File

To decompile a specific class file into Java source, use the decompile.sh script. This requires Java (JRE) to be installed in the environment.

# Example: Decompile com.example.MyClass from myapp.jar into the current directory
./scripts/decompile.sh <path_to_jar> <fully_qualified_class_name> [output_directory]

The script uses the CFR decompiler (assets/cfr-0.152.jar).

4. Extract a Specific File

If you need to pull a resource (e.g., a .properties or .xml file) out of the JAR:

python3 scripts/jar_explorer.py extract <path_to_jar> <file_path_in_jar>

Troubleshooting

• Java Not Found: The decompiler requires Java. If java is not in your path, you will only be able to list and extract files.
• Class Not Found: When decompiling, ensure you use the fully qualified class name (e.g., com.example.Main) or the path inside the JAR (e.g., com/example/Main.class).
• Permissions: Ensure scripts in the scripts/ directory have execution permissions (chmod +x scripts/decompile.sh).

Bundled Resources

• scripts/jar_explorer.py: Python script for listing, manifest viewing, and extraction.
• scripts/decompile.sh: Shell script wrapper for the CFR decompiler.
• assets/cfr-0.152.jar: The CFR Java decompiler.