MongoDB Java Reactive Streams

Introduction

Welcome to the documentation site for the Reactive Streams Driver, the official MongoDB driver for asynchronous Java applications. Download it by following the Installation Guide or set up a runnable project by following our tutorials.

• Reference Documentation

• Tutorials

• API Documentation

• What's New

• Source Code

If you need to make synchronous calls between your application and MongoDB, use the MongoDB Java Driver instead of the Reactive Streams Driver.

Installation

The recommended way to get started using the driver in your project is with a dependency management system. See the Installation Guide for more information.

Connect to MongoDB Atlas

To connect to a MongoDB Atlas cluster, use the Atlas connection string for your cluster:

import com.mongodb.ConnectionString;
import com.mongodb.reactivestreams.client.MongoClients;
import com.mongodb.reactivestreams.client.MongoClient;
import com.mongodb.reactivestreams.client.MongoDatabase;
import com.mongodb.MongoClientSettings;
// ...
// Replace the uri string with your MongoDB deployment's connection string.
ConnectionString connString = new ConnectionString(
    "mongodb+srv://<username>:<password>@<cluster-address>/test?w=majority"
);
MongoClientSettings settings = MongoClientSettings.builder()
    .applyConnectionString(connString)
    .retryWrites(true)
    .build();
MongoClient mongoClient = MongoClients.create(settings);
MongoDatabase database = mongoClient.getDatabase("test");

See Connect to MongoDB for more ways to connect.

Stable API

You can use the Stable API feature starting with MongoDB Server version 5.0 and Java Reactive Streams Driver version 4.3. When you use the Stable API feature, you can update your driver or server without worrying about backward compatibility issues with any commands covered by the Stable API.

To use this feature, construct a MongoDB client instance, specifying a version of the Stable API:

import com.mongodb.ConnectionString;
import com.mongodb.MongoClientSettings;
import com.mongodb.ServerApi;
import com.mongodb.ServerApiVersion;
import com.mongodb.reactivestreams.client.MongoClient;
import com.mongodb.reactivestreams.client.MongoClients;
// ...
// Replace <connection string> with your MongoDB deployment's connection string.
ConnectionString connString = new ConnectionString("<connection string>");
// Set the Stable API version on the client.
ServerApi serverApi = ServerApi.builder()
        .version(ServerApiVersion.V1)
         .build();
MongoClientSettings settings = MongoClientSettings.builder()
         .applyConnectionString(connString)
         .serverApi(serverApi)
         .build();
MongoClient mongoClient = MongoClients.create(settings);

Connect to a MongoDB Server on Your Local Machine

If you need to run a MongoDB server on your local machine for development purposes instead of using an Atlas cluster, you need to complete the following:

1. Download the Community or Enterprise version of MongoDB Server.

2. Install and configure MongoDB Server.

3. Start the server.

After you successfully start your MongoDB server, specify your connection string in your driver connection code.

If your MongoDB Server is running locally, you can use the connection string "mongodb://localhost:<port>" where <port> is the port number you configured your server to listen for incoming connections.

If you need to specify a different hostname or IP address, see our Server Manual entry on Connection Strings.

To test whether you can connect to your server, replace the connection string in the Connect to MongoDB Atlas code example and run it.

Compatibility