Add warning message in Eclipse for missing tools.jar on boot-java ls

eclipse-language-servers/org.springframework.tooling.boot.java.ls/src/org/springframework/tooling/boot/java/ls/MissingToolsJarWarning.java

@@ -0,0 +1,50 @@
+/*******************************************************************************
+ * Copyright (c) 2018 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.tooling.boot.java.ls;
+
+import java.io.File;
+
+import org.eclipse.jface.dialogs.MessageDialog;
+import org.eclipse.swt.widgets.Display;
+import org.springframework.tooling.ls.eclipse.commons.STS4LanguageServerProcessStreamConnector.MissingToolsJarException;
+
+public class MissingToolsJarWarning {
+
+	private static boolean missingToolsJarWarningIssued = false;
+	
+	public static void show(MissingToolsJarException e) {
+		Display.getDefault().asyncExec(() -> {
+			
+			//Don't warn more than once per Eclipse session.
+			if (!missingToolsJarWarningIssued) {
+				missingToolsJarWarningIssued = true;
+				
+				StringBuilder lookedIn = new StringBuilder();
+				for (File file : e.lookedIn) {
+					lookedIn.append("  ");
+					lookedIn.append(file);
+					lookedIn.append("\n");
+				}
+				
+				MessageDialog.openWarning(null, "Missing 'tools.jar'", 
+						"Could not find 'tools.jar' in the active JRE.\n\n"+
+						"Spring Boot Live hovers will not work without it.\n\n" +
+						"The JRE you are running Eclipse with is:\n  "+e.javaHome+"\n\n" +
+						"Where we looked for 'tools.jar':\n" +
+						lookedIn
+				);
+			}
+		});
+	}
+
+
+
+}

eclipse-language-servers/org.springframework.tooling.boot.java.ls/src/org/springframework/tooling/boot/java/ls/SpringBootJavaLanguageServer.java

@@ -39,7 +39,16 @@ public class SpringBootJavaLanguageServer extends STS4LanguageServerProcessStrea
 		commands.add("-Dlsp.completions.indentation.enable=true");
 		commands.add("-Xmx1024m");
 		commands.add("-cp");
-		commands.add(getToolsJAR() + File.pathSeparator + getLanguageServerJARLocation());
+		String classpath = getLanguageServerJARLocation();
+		try {
+			File toolsJar = getToolsJAR();
+			if (toolsJar!=null) {
+				classpath = toolsJar + File.pathSeparator + classpath;
+			}
+		} catch (MissingToolsJarException e) {
+			MissingToolsJarWarning.show(e);
+		}
+		commands.add(classpath);
 		commands.add("org.springframework.boot.loader.JarLauncher");
 
 		String workingDir = getWorkingDirLocation();

eclipse-language-servers/org.springframework.tooling.ls.eclipse.commons/src/org/springframework/tooling/ls/eclipse/commons/STS4LanguageServerProcessStreamConnector.java

@@ -12,14 +12,27 @@ package org.springframework.tooling.ls.eclipse.commons;
 
 import java.io.File;
 import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
 
-import org.eclipse.core.runtime.Path;
 import org.eclipse.jdt.internal.launching.StandardVMType;
 import org.eclipse.lsp4e.server.ProcessStreamConnectionProvider;
 
 @SuppressWarnings("restriction")
 public class STS4LanguageServerProcessStreamConnector extends ProcessStreamConnectionProvider {
 
+	public static class MissingToolsJarException extends Exception {
+		
+		public final File javaHome;
+		public final List<File> lookedIn;
+		
+		public MissingToolsJarException(File javaHome, List<File> lookedIn) {
+			super();
+			this.javaHome = javaHome;
+			this.lookedIn = lookedIn;
+		}
+	}
+
 	private static LanguageServerProcessReaper processReaper = new LanguageServerProcessReaper();
 	
 	@Override
@@ -50,9 +63,32 @@ public class STS4LanguageServerProcessStreamConnector extends ProcessStreamConne
 		return null;
 	}
 	
-	protected String getToolsJAR() {
-		File jre = new File(System.getProperty("java.home"));
-		return new File(jre.getParent(), "lib" + Path.SEPARATOR + "tools.jar").getAbsolutePath();
+	/**
+	 * Different places to look for tools jar, relative to Java home.
+	 */
+	private static String[] TOOLS_JAR_PATHS = {
+			"../lib/tools.jar",
+			"lib/tools.jar"
+	};
+	
+	/**
+	 * Get a tools jar if it is needed based on current JRE version.
+	 * 
+	 * @return The tools.jar, or null if none is needed.
+	 * @throws MissingToolsJarException If tools jar is needed but could not be found.
+	 */
+	protected File getToolsJAR() throws MissingToolsJarException {
+		List<File> lookedIn = new ArrayList<>();
+		File jhome = new File(System.getProperty("java.home"));
+//		resolve(System.getenv("JAVA_HOME"), jhomes::add);
+		for (String tjPath : TOOLS_JAR_PATHS) {
+			File toolsJar = new File(jhome, tjPath).toPath().normalize().toFile();
+			lookedIn.add(toolsJar);
+			if (toolsJar.isFile()) {
+				return toolsJar;
+			}
+		}
+		throw new MissingToolsJarException(jhome, lookedIn);
 	}
 	
 	protected String getWorkingDirLocation() {