Java 16: added example of Unix-Domain socket

Author: wesleyegberto

README.md

@@ -17,6 +17,7 @@ A project to explore more about the new features of Java 8, 9, ...
   * Records (standard)
   * Pattern matching for `instanceof` (standard)
   * Sealed classes (preview 2)
+  * Unix-Domain Socket Channels
   * Warnings for Value-Based Classes
   * Foreign-Memory Access API (incubator)
   * Vector API (Incubator)

java-16/README.md

@@ -18,6 +18,7 @@ To run each example use: `java --enable-preview --source 16 <FileName.java>`
   * change in the API
 * Sealed classes (second preview)
   * `sealed`, `non-sealed` and `permits` became contextual keywords (we can use it as var name or method name)
+* Unix-Domain Socket Channels
 
 ### JVM
 

java-16/UnixDomainSocketTest.java

@@ -0,0 +1,83 @@
+import java.io.IOException;
+import java.net.StandardProtocolFamily;
+import java.net.UnixDomainSocketAddress;
+import java.nio.channels.*;
+import java.nio.*;
+import java.nio.file.*;
+import java.rmi.server.SocketSecurityException;
+
+public class UnixDomainSocketTest {
+	private static final String SOCKET_PATH = "server.socket";
+
+	public static void main(String[] args) throws Exception {
+		var socketFile = Path.of(System.getProperty("user.home")).resolve(SOCKET_PATH);
+		var address = UnixDomainSocketAddress.of(socketFile);
+
+		Thread.sleep(500);
+		new Thread(new ServerProcess(address)).start();
+
+		Thread.sleep(1000);
+		new Thread(new ClientProcess(address)).start();
+
+		Thread.currentThread().join(10_000);
+	}
+}
+
+class ServerProcess implements Runnable {
+	private final UnixDomainSocketAddress address;
+
+	ServerProcess(UnixDomainSocketAddress address) {
+		this.address = address;
+	}
+
+	public void run() {
+		try (ServerSocketChannel server = ServerSocketChannel.open(StandardProtocolFamily.UNIX)) {
+			server.bind(this.address);
+
+			System.out.println("[Server] starting");
+			SocketChannel channel = server.accept();
+
+			System.out.println("[Server] sending message");
+			channel.write(ByteBuffer.wrap("Hello client!".getBytes()));
+
+			var buffer = ByteBuffer.allocate(1024);
+			var length = channel.read(buffer);
+			if (length > 0) {
+				System.out.println("[Server] message from client: " + new String(buffer.array()));
+			} else {
+				System.out.println("[Server] empty");
+			}
+			channel.close();
+		} catch (IOException ex) {
+			ex.printStackTrace();
+		}
+	}
+}
+
+class ClientProcess implements Runnable {
+	private final UnixDomainSocketAddress address;
+
+	ClientProcess(UnixDomainSocketAddress address) {
+		this.address = address;
+	}
+
+	public void run() {
+		try (SocketChannel client = SocketChannel.open(StandardProtocolFamily.UNIX)) {
+			System.out.println("[Client] starting");
+			client.connect(this.address);
+
+			System.out.println("[Client] reading message");
+			var buffer = ByteBuffer.allocate(1024);
+			var length = client.read(buffer);
+			if (length > 0) {
+				System.out.println("[Client] message from the server: " + new String(buffer.array()));
+			} else {
+				System.out.println("[Client] empty");
+			}
+			System.out.println("[Client] sending message");
+			client.write(ByteBuffer.wrap("Hello server, I'm your new client!".getBytes()));
+		} catch (IOException ex) {
+			ex.printStackTrace();
+		}
+	}
+}