Langchain4j Rag Implementation Patterns

This implements RAG systems in Java using LangChain4j, handling the full pipeline from document ingestion through vector search to context-aware responses. You get document splitters with token counting, embedding store configuration (in-memory by default), and retrieval with configurable similarity thresholds. The skill includes validation checkpoints to verify embedding counts match segments and test retrieval before going live. It's built for Spring Boot projects and assumes you're working with OpenAI embeddings, though the patterns apply to other providers. The hierarchical RAG example is worth looking at if you're dealing with large document sets where you want to search summaries first, then drill into chunks. Code is production-ready with proper error handling and metadata support.

skills.sh installs: 3.9K
GitHub stars: 369
last updated: Aug 21, 2026

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Install

$ npx -y skills add giuseppe-trisciuoglio/developer-kit --skill langchain4j-rag-implementation-patterns --agent claude-code

Installs into .claude/skills of the current project.

Files

LangChain4j RAG Implementation Patterns

Overview

Implements RAG systems with LangChain4j: document ingestion pipelines, embedding stores, and vector search for chat-with-documents and knowledge-enhanced AI applications.

When to Use This Skill

Building chat-with-documents systems or document Q&A over PDFs, text files, or web pages
Creating AI assistants with access to company knowledge bases or external sources
Implementing semantic search or hybrid search over document repositories
Building domain-specific AI with curated knowledge and source attribution

Instructions

Initialize RAG Project

Create a new Spring Boot project with required dependencies:

pom.xml:

<dependency>
    <groupId>dev.langchain4j</groupId>
    <artifactId>langchain4j-spring-boot-starter</artifactId>
    <version>1.8.0</version>
</dependency>
<dependency>
    <groupId>dev.langchain4j</groupId>
    <artifactId>langchain4j-open-ai</artifactId>
    <version>1.8.0</version>
</dependency>