added mode to connect vscode extension to running language server

vscode-extensions/vscode-boot-java/src/main/java/org/springframework/ide/vscode/boot/java/StartupServer.java

@@ -0,0 +1,78 @@
+/*******************************************************************************
+ * Copyright (c) 2017 Pivotal, Inc.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ * Pivotal, Inc. - initial API and implementation
+ *******************************************************************************/
+package org.springframework.ide.vscode.boot.java;
+
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.net.SocketAddress;
+import java.nio.channels.AsynchronousServerSocketChannel;
+import java.nio.channels.AsynchronousSocketChannel;
+import java.nio.channels.Channels;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.function.Function;
+
+import org.eclipse.lsp4j.jsonrpc.Launcher;
+import org.eclipse.lsp4j.jsonrpc.MessageConsumer;
+import org.springframework.ide.vscode.commons.languageserver.STS4LanguageClient;
+import org.springframework.ide.vscode.commons.languageserver.java.JavaProjectFinder;
+import org.springframework.ide.vscode.commons.languageserver.util.SimpleLanguageServer;
+
+/**
+ * starts up the language server and let it listen for connections from the outside
+ * instead of connecting itself to an existing port or channel.
+ * 
+ * This is meant for development only, to reduce turnaround times while working
+ * on the language server from within an IDE, so that you can start the language
+ * server right away in debug mode and let the vscode extension connect to that
+ * instance instead of vice versa.
+ * 
+ * Source of inspiration:
+ * https://github.com/itemis/xtext-languageserver-example/blob/master/org.xtext.example.mydsl.ide/src/org/xtext/example/mydsl/ide/RunServer.java
+ * 
+ * @author Martin Lippert
+ */
+public class StartupServer {
+
+	public static void main(String[] args) throws InterruptedException, IOException {
+
+		JavaProjectFinder javaProjectFinder = BootJavaLanguageServer.DEFAULT_PROJECT_FINDER;
+		SimpleLanguageServer languageServer = new BootJavaLanguageServer(javaProjectFinder);
+
+		Function<MessageConsumer, MessageConsumer> wrapper = consumer -> {
+			MessageConsumer result = consumer;
+			return result;
+		};
+		
+		Launcher<STS4LanguageClient> launcher = createSocketLauncher(languageServer, STS4LanguageClient.class, new InetSocketAddress("localhost", 5007), Executors.newCachedThreadPool(), wrapper);
+
+		languageServer.connect(launcher.getRemoteProxy());
+		Future<?> future = launcher.startListening();
+		while (!future.isDone()) {
+			Thread.sleep(10_000l);
+		}
+	}
+	
+    private static <T> Launcher<T> createSocketLauncher(Object localService, Class<T> remoteInterface, SocketAddress socketAddress, ExecutorService executorService, Function<MessageConsumer, MessageConsumer> wrapper) throws IOException {
+        AsynchronousServerSocketChannel serverSocket = AsynchronousServerSocketChannel.open().bind(socketAddress);
+        AsynchronousSocketChannel socketChannel;
+        try {
+            socketChannel = serverSocket.accept().get();
+            return Launcher.createIoLauncher(localService, remoteInterface, Channels.newInputStream(socketChannel), Channels.newOutputStream(socketChannel), executorService, wrapper);
+        } catch (InterruptedException | ExecutionException e) {
+            e.printStackTrace();
+        }
+        return null;
+    }
+
+}