Speer is a library used to perform P2P communication easier. It uses the plain Java Socket API to allow communicating between two devices.

You can consult the wiki for a detailed documentation

Take a look at Fandem a P2P file sharing app. This project uses speer to send/receive files between devices in P2P, and also to discover Fandem peers with UDP.

Server-side

import com.tambapps.p2p.speer.PeerServer

try (PeerServer server = peerServer();
     PeerConnection connection = server.accept()) {
  connection.writeUTF("Hello! do you want to talk to me?");
  if ("yes".equals(connection.readUTF())) {
    talk(connection);
  }
}

Client-side

try (PeerConnection connection = PeerConnection.from(peer)) {
  connection.readUTF()
  connection.writeUTF("yes")
  talk(connection)
}

This library is hosted on Jitpack

You can import it to your project by adding the Jitpack repository

  <repositories>
    <repository>
      <id>jitpack.io</id>
      <url>https://jitpack.io</url>
    </repository>
  </repositories>

And then add the dependency

  <dependency>
    <groupId>com.github.tambapps</groupId>
    <artifactId>speer</artifactId>
    <version>1.0</version>
  </dependency>