## JFFL – Javassist Framework for Forge Loader<\/p>\n
JFFL is a bytecode manipulation library for Minecraft Forge based on Javassist, providing Mixin-like declarative patch injection capabilities. It allows developers to modify classes from Minecraft and other mods at runtime using annotations, without the need to write low-level ASM or Javassist code directly.<\/p>\n
—<\/p>\n
## Features<\/p>\n
– Declarative Annotation-Driven
\n – Callback Handlers
\n – Mapping Remapping Support
\n – Flexible Injection Points<\/p>\n
—<\/p>\n
## Installation and Dependencies<\/p>\n
“`gradle
\nrepositories {
\n \/\/ Put the .jar of JFFL mod into the libs folder
\n flatDir {
\n dir ‘libs’
\n }
\n}
\n\/\/ Write in dependencies (replace {versino} with the actual version number):
\ndependencies {
\n implementation fg.deobf(“wertygh:jffl:{version}”)
\n}
\n“`<\/p>\n
—<\/p>\n
## Relationship with Mixin<\/p>\n
JFFL is not a replacement for Mixin but rather provides an alternative option. Both can coexist, though applying both to the same class is not recommended as it may lead to unexpected conflicts. JFFL’s advantages include:<\/p>\n
– Lightweight, based on Javassist source-level operations, easier to debug
\n – Supports dynamic callback registration without generating synthetic methods<\/p>\n
—<\/p>\n
## Development and Debugging<\/p>\n
In development environment (jffl.dev=true):<\/p>\n
– JFFL outputs detailed logs
\n – Use @DumpClass to output modified classes to the .jffl-dump directory
\n – Supports direct use of MCP\/Mojang names without loading mappings<\/p>\n
—<\/p>\n
## License<\/p>\n
BSD Zero Clause License<\/p>\n
—<\/p>\n
## Contribution and Feedback<\/p>\n
Issues and Pull Requests are welcome!
\nProject author: wertygh<\/p>\n","protected":false},"excerpt":{"rendered":"
JFFL is a tool used to Javassist of Minecraftforge bytecode operation library, provides mixin-like declarative patch injection it allows developers to use annotations at startup to modify the Minecraft and other mod classes.<\/p>\n","protected":false},"featured_media":87980,"template":"","meta":{"_minecraft_slug":"jffl","_minecraft_project_id":"lTm9zXaK","_minecraft_author":"wertygh","_minecraft_license":"Apache-2.0","_minecraft_downloads":12,"_minecraft_follows":0,"_minecraft_client_side":"required","_minecraft_server_side":"required","_minecraft_storage_type":"zip","_minecraft_archive_name":"jffl.zip","_minecraft_size_bytes":3226238,"_minecraft_version_count":2,"_minecraft_updated_at":"2026-05-16T12:21:45.438410Z","_minecraft_date_created":"2026-05-12T06:01:15.278844Z","_minecraft_date_modified":"2026-05-14T13:28:54.759352Z","_minecraft_project_url":"https:\/\/modrinth.com\/mod\/jffl","_minecraft_icon_attachment_id":87980,"_minecraft_imported_at":"2026-06-05T00:41:15+00:00","_minecraft_import_hash":"24b3b9921cc30c712b817f4e1604a2c5","_minecraft_versions":"","_minecraft_links":"","_minecraft_gallery":"","_minecraft_api_metadata":""},"mod_category":[104,873],"mod_loader":[106],"minecraft_version":[36,60,93,94,101,102],"class_list":["post-87979","mod","type-mod","status-publish","has-post-thumbnail","hentry","mod_category-forge","mod_category-library","mod_loader-forge","minecraft_version-1-20-1","minecraft_version-1-20-2","minecraft_version-1-20-3","minecraft_version-1-20-4","minecraft_version-1-20-5","minecraft_version-1-20-6"],"yoast_head":"\n