ease debugging and development of the boot java ls by connecting both sides via a socket on demand

eclipse-language-servers/org.springframework.boot.ide.java.servers/plugin.xml

@@ -5,7 +5,7 @@
    <extension
          point="org.eclipse.lsp4e.languageServer">
       <server
-            class="org.springframework.boot.ide.java.servers.SpringBootJavaLanguageServer"
+            class="org.springframework.boot.ide.java.servers.DelegatingStreamConnectionProvider"
             id="org.eclipse.languageserver.languages.springbootjava"
             label="Spring Boot Java Language Server">
       </server>

eclipse-language-servers/org.springframework.boot.ide.java.servers/src/org/springframework/boot/ide/java/servers/DelegatingStreamConnectionProvider.java

@@ -0,0 +1,65 @@
+/*******************************************************************************
+ * 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.boot.ide.java.servers;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+import org.eclipse.lsp4e.server.StreamConnectionProvider;
+
+/**
+ * if the system property "boot-java-ls-port" exists, delegate to the socket-based
+ * stream connection provider, otherwise use the standard process-based stream
+ * connection provider.
+ * 
+ * This allows you to run the language server in server mode (listens on a port for
+ * a connection) and connect the IDE integration to that already running language
+ * server instead of starting a new process for it.
+ * 
+ * @author Martin Lippert
+ */
+public class DelegatingStreamConnectionProvider implements StreamConnectionProvider {
+	
+	private StreamConnectionProvider provider;
+	
+	public DelegatingStreamConnectionProvider() {
+		String port = System.getProperty("boot-java-ls-port");
+		
+		if (port != null) {
+			this.provider = new SpringBootJavaLanguageServerViaSocket(Integer.parseInt(port));
+		}
+		else {
+			this.provider = new SpringBootJavaLanguageServer();
+		}
+	}
+	
+	@Override
+	public void start() throws IOException {
+		this.provider.start();
+	}
+
+	@Override
+	public InputStream getInputStream() {
+		return this.provider.getInputStream();
+	}
+
+	@Override
+	public OutputStream getOutputStream() {
+		return this.provider.getOutputStream();
+	}
+
+	@Override
+	public void stop() {
+		this.provider.stop();
+	}
+
+}

eclipse-language-servers/org.springframework.boot.ide.java.servers/src/org/springframework/boot/ide/java/servers/SpringBootJavaLanguageServerViaSocket.java

@@ -0,0 +1,64 @@
+/*******************************************************************************
+ * 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.boot.ide.java.servers;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.net.Socket;
+
+import org.eclipse.lsp4e.server.StreamConnectionProvider;
+
+public class SpringBootJavaLanguageServerViaSocket implements StreamConnectionProvider {
+	
+	private OutputStream outputStream;
+	private InputStream inputStream;
+	private Socket socket;
+	private int port;
+
+	public SpringBootJavaLanguageServerViaSocket(int port) {
+		this.port = port;
+	}
+
+	@Override
+	public void start() throws IOException {
+		try {
+			socket = new Socket("localhost", port);
+			outputStream = socket.getOutputStream();
+			inputStream = socket.getInputStream();
+		}
+		catch (IOException e) {
+			e.printStackTrace();
+		}
+	}
+
+	@Override
+	public InputStream getInputStream() {
+		return inputStream;
+	}
+
+	@Override
+	public OutputStream getOutputStream() {
+		return outputStream;
+	}
+
+	@Override
+	public void stop() {
+		if (socket != null) {
+			try {
+				socket.close();
+			} catch (IOException e) {
+				e.printStackTrace();
+			}
+		}
+	}
+
+}