Java MCP Connector

This is a pure Java implementation of a connector for the MCP (Model Context Protocol. It acts as a bridge between any MCP-compatible client (like Claude or OpenAI tools) and a standard HTTP backend (like a Spring Boot or Node.js server). You can use with a2ajava which is pure java implementation of A2A protocol and works with MCP protocol as well .

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🔧 How It Works

The connector acts as a Passthrough Server. It reads JSON-RPC 2.0 messages from stdin, forwards them as HTTP POSTs to a specified backend URL, and returns the HTTP response as the output to stdout.

🔁 Flow

1. MCP Tool sends a JSON-RPC message to the connector (via stdin).
2. Connector receives and parses the input.
3. It sends the message as an HTTP POST to your backend (e.g., http://localhost:8080).
4. The backend returns a JSON-RPC-compliant response.
5. Connector prints the response to stdout for the AI tool to consume.

This allows any language backend (Spring, Flask, Express, etc.) to seamlessly speak MCP.

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🧪 Example Claude Tool Configuration

Update your Claude Desktop tool configuration to use this Java connector:

"routeplanningagent": {
  "command": "java",
  "args": [
    "-jar",
    "/work/a2a-mcp-bridge/target/mcp-connector-full.jar",
    "http://localhost:8080"
  ],
  "timeout": 30000
}

or with username

,"laundry": {
  "command": "java",
  "args": [    
    "-jar",
    "/work/a2a-mcp-bridge/target/mcp-connector-full.jar",
    "http://localhost:7860/" ,"user","password"
  ],
  "timeout": 30000
} 

For other types of connectors in python, shell , nodejs please read the guide

🚀 Why Use a Java Connector?

• ✅ Language Independence You don’t need to implement MCP in your backend; just handle HTTP POSTs.

• ✅ Better Portability Can be bundled into a single JAR with all dependencies. Run it on any system with Java.

• ✅ Production Ready Java is battle-tested for high performance and robust networking.

• ✅ No NodeJS or Python Needed Ideal for environments with strict runtime policies (e.g., enterprise setups).

• ✅ Custom Logic Support Easily add authentication, logging, metrics, or normalization of payloads.

🏗️ Build Instructions Build the connector with Maven:

mvn clean package

This generates a fat JAR:

💡 Advanced Features Normalizer Support: (Optional) You can add a RequestNormalizer class to rewrite or preprocess requests before they reach the backend.

Debug Logging: All input/output is logged to stderr for easy debugging.