Category: spring_boot
What is RAG and how to use in java
Published on 07 Jun 2026
Explanation
What is RAG (Retrieval-Augmented
Generation)? RAG
enhances LLM responses by
retrieving relevant
information from external data sources
before
generating an answer.
Code:
// User Question -> Retrieve Context -> LLM -> Answer
Explanation
Step 1: Load documents and create
embeddings. Documents are split into chunks
and converted into vector representations.
Code:
String text = Files.
readString(Paths.get("document.txt"));
Embedding embedding =
embeddingModel.embed(text);
Explanation
Step 2: Store embeddings in a
vector database such as Qdrant, ChromaDB,
or Milvus for efficient similarity search.
Code:
vectorStore.add(List.of(new Document(text)));
Explanation
Step 3: Retrieve relevant document chunks
based on the user's question and
build a prompt with the retrieved
context.
Code:
List<Document> docs = . vectorStore.similaritySearch(question); String prompt = "Context:\n" + context + "\nQuestion:\n" + question;
Explanation
Step 4: Generate the final answer
using an LLM. Common Java stack:
Spring Boot + Spring AI +
Ollama + Qdrant.
Code:
String answer = chatModel.call(prompt);