* INITIAL POPULATIONS OF THIS REPO

2021-12-23 13:04:01 +08:00
parent 3165defa2e
commit ed70cad6ea
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+/******************************************************************************
+*
+* Copyright: Intellectual Property of Four Elements Capital Pte Ltd, Singapore.
+* All rights reserved.
+*
+******************************************************************************/
+
+package com.fourelementscapital.socket;
+
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.net.SocketAddress;
+import java.nio.ByteBuffer;
+import java.nio.channels.AsynchronousServerSocketChannel;
+import java.nio.channels.AsynchronousSocketChannel;
+import java.nio.channels.CompletionHandler;
+import java.nio.charset.Charset;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+
+/**
+ * Socket Server to listen & process client's message after receive it 
+ */
+public class SocketServer {
+	
+	private static final Logger log = LogManager.getLogger(SocketServer.class.getName());
+	
+	/**
+	 * Listening message and process it. Use SocketProcess as dependency injection.
+	 * @param socketProcess SocketProcess as dependency injection to process message
+	 * @throws Exception
+	 */	
+	public static void listen(SocketProcess socketProcess) throws Exception {
+	    AsynchronousServerSocketChannel server = AsynchronousServerSocketChannel.open();
+	    String host = "0.0.0.0"; // all IPs available on this host 
+	    int port = Integer.parseInt(Config.getConfigValue("socket_server_port_number"));
+	    InetSocketAddress sAddr = new InetSocketAddress(host, port);
+	    server.bind(sAddr);
+	    System.out.print(String.format("Server is listening at %s%n", sAddr)); // sysout, not log
+	    AttachmentServer attach = new AttachmentServer();
+	    attach.server = server;
+	    attach.socketProcess = socketProcess;
+	    server.accept(attach, new ConnectionHandlerServer());
+	    Thread.currentThread().join();
+	}	
+}
+
+/**
+ * Class as value container to be passed among methods
+ */
+class AttachmentServer {
+	AsynchronousServerSocketChannel server;
+	AsynchronousSocketChannel client;
+	ByteBuffer buffer;
+	SocketAddress clientAddr;
+	SocketProcess socketProcess;
+}
+
+
+/**
+ * Server connection handler
+ */
+class ConnectionHandlerServer implements CompletionHandler<AsynchronousSocketChannel, AttachmentServer> {
+	
+	private static final Logger log = LogManager.getLogger(ConnectionHandlerServer.class.getName());
+	
+	private static final int BUFFER_ALLOCATED_IN_BYTE = 10000;  // how many chars allowed in 1 socket message;
+	
+	/**
+	 * An override method to be processed after operation has completed
+	 * @param client AsynchronousSocketChannel object
+	 * @param attach AttachmentServer object
+	 */		
+	@Override
+	public void completed(AsynchronousSocketChannel client, AttachmentServer attach) {
+		try {
+			SocketAddress clientAddr = client.getRemoteAddress();
+			System.out.print(String.format("Accepted connection from %s%n", clientAddr));  // sysout, not log
+			attach.server.accept(attach, this);
+			ReadWriteHandlerServer rwHandler = new ReadWriteHandlerServer();
+			AttachmentServer newAttach = new AttachmentServer();
+			newAttach.server = attach.server;
+			newAttach.client = client;
+			//newAttach.buffer = ByteBuffer.allocate(2048);
+			newAttach.buffer = ByteBuffer.allocate(BUFFER_ALLOCATED_IN_BYTE);
+			newAttach.clientAddr = clientAddr;
+			newAttach.socketProcess = attach.socketProcess;
+			client.read(newAttach.buffer, newAttach, rwHandler);
+		} catch (IOException e) {
+			e.printStackTrace();
+		}
+	}
+
+	/**
+	 * An override method to be processed when operation fails
+	 * @param e Throwable object
+	 * @param attach AttachmentServer object
+	 */		
+	@Override
+	public void failed(Throwable e, AttachmentServer attach) {
+		log.error("Failed to accept a connection.");
+		e.printStackTrace();
+	}
+}
+
+
+/**
+ * Class to read / write process
+ */
+class ReadWriteHandlerServer implements CompletionHandler<Integer, AttachmentServer> {
+	
+	private static final Logger log = LogManager.getLogger(ReadWriteHandlerServer.class.getName());
+	
+	/**
+	 * An override method to be processed after operation has completed
+	 * @param result Result
+	 * @param attach AttachmentServer object
+	 */		
+	@Override
+	public void completed(Integer result, AttachmentServer attach) {
+		
+    	attach.buffer.flip();
+    	int limits = attach.buffer.limit();
+    	byte bytes[] = new byte[limits];
+    	attach.buffer.get(bytes, 0, limits);		
+    	Charset cs = Charset.forName("UTF-8");
+    	String msg = new String(bytes, cs);
+    	log.debug("SocketProcess.run() message : " + msg);
+		attach.socketProcess.run(msg); // run socket process
+		
+		attach.buffer.rewind();
+	}
+
+	/**
+	 * An override method to be processed when operation fails
+	 * @param e Throwable object
+	 * @param attach AttachmentServer object
+	 */			
+	@Override
+	public void failed(Throwable e, AttachmentServer attach) {
+		e.printStackTrace();
+	}
+}
+
+
+