A Model Context Protocol (MCP) server implementation built with Spring Boot and Java 21. This project demonstrates how to create an MCP server that provides user management tools for AI assistants.

• Implements MCP server functionality using Spring AI
• Exposes user management tools via MCP
• Synchronous communication mode
• Support for Standard I/O and Server-Sent Events transports
• Integrates with DummyJSON external API for user data

• Java 21
• Spring Boot 3.4.3
• Spring AI (Model Context Protocol)
• Project Lombok
• Maven

• Java 21 or higher
• Maven

1. Clone the repository

git clone https://github.com/yourusername/mcp-spring-java.git cd mcp-spring-java

2. Build the project

mvn clean package

3. Run the application

java -jar target/mcp-spring-java-0.0.1-SNAPSHOT.jar

The MCP server is configured in application.yml:

• Server runs on port 8090
• Server name: my-dummy-users-server
• Synchronous communication mode
• Supports STDIO transport for terminal-based communication
• Exposes /mcp/message endpoint for SSE communication

The server exposes the following user management tools:

• getAllUsers - Get all users with pagination
• getAllUsersDefault - Get all users with default pagination
• getUserById - Get a single user by ID
• searchUsers - Search for users by query
• addUser - Add a new user
• updateUser - Update a user
• deleteUser - Delete a user

You can use Postman to test the MCP server endpoints:

1. Start the MCP server

2. Open Postman and create a new request:

   • Method: POST
   • URL: http://localhost:8090/mcp/message
   • Headers:
     • Content-Type: application/json
     • Accept: application/json

3. For the request body, use the following JSON format to invoke any of the available tools:

{ "message": { "toolCalls": [ { "id": "call-123", "name": "[TOOL_NAME]", "parameters": { "[PARAMETER_NAME]": "[PARAMETER_VALUE]" } } ] } }

{ "message": { "toolCalls": [ { "id": "call-123", "name": "getAllUsersDefault", "parameters": {} } ] } }

{ "message": { "toolCalls": [ { "id": "call-123", "name": "getUserById", "parameters": { "id": 1 } } ] } }

{ "message": { "toolCalls": [ { "id": "call-123", "name": "searchUsers", "parameters": { "query": "John" } } ] } }

The response will contain a JSON object with the results from the tool execution.

You can configure this server in MCP client applications using the following configuration:

{ "mcpServers": { "dummy-user-server": { "command": "java", "args": [ "-Dspring.ai.mcp.server.stdio=true", "-Dspring.main.web-application-type=none", "-Dlogging.pattern.console=", "-jar", "path/to/mcp-spring-java-0.0.1-SNAPSHOT.jar" ] } } }

This project is licensed under the terms provided in the LICENSE file.