Revert "Always run javadoc using the ToolProvider API"

This reverts commit f70aeb5e, except for some commented-out parts of
code and an unused method. I also simplified the code, e.g. with regard
to exception handling, and did some more cosmetic stuff, but basically
it is a revert.

In order to make it compile on more recent JDKs which doe not have class
com.sun.tools.javadoc.Main, I used Class.forName in the method being
called on JDK 8 only.

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>

ajdoc/src/main/java/org/aspectj/tools/ajdoc/JavadocRunner.java

@@ -1,39 +1,55 @@
 /* *******************************************************************
- * Copyright (c) 1999-2001 Xerox Corporation, 
+ * Copyright (c) 1999-2001 Xerox Corporation,
  *               2002 Palo Alto Research Center, Incorporated (PARC).
- * 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: 
- *     Xerox/PARC     initial implementation 
+ * 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:
+ *     Xerox/PARC     initial implementation
  *     Mik Kersten	  port to AspectJ 1.1+ code base
  * ******************************************************************/
 
 package org.aspectj.tools.ajdoc;
 
-import java.util.List;
-import java.util.Vector;
-
 import javax.tools.DocumentationTool;
 import javax.tools.DocumentationTool.DocumentationTask;
 import javax.tools.JavaFileObject;
 import javax.tools.StandardJavaFileManager;
 import javax.tools.ToolProvider;
+import java.lang.reflect.InvocationTargetException;
+import java.util.List;
 
 /**
  * @author Mik Kersten
  */
 class JavadocRunner {
 
+	static void callJavadoc(String[] javadocArgs) {
+		try {
+			Class.forName("com.sun.tools.javadoc.Main")
+				.getMethod("execute", String[].class)
+				.invoke(null, new Object[] { javadocArgs });
+		}
+		catch (ClassNotFoundException | NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
+			throw new RuntimeException("Failed to invoke javadoc", e);
+		}
+	}
+
 	public static void callJavadocViaToolProvider(Iterable<String> options, List<String> files) {
-		DocumentationTool doctool = ToolProvider.getSystemDocumentationTool();
-		StandardJavaFileManager fm = doctool.getStandardFileManager(null, null, null);
-		Iterable<? extends JavaFileObject> jfos = fm.getJavaFileObjects(files.toArray(new String[0]));
-		DocumentationTask task = doctool.getTask(null/*standard System.err*/, null/*standard file manager*/,
-				null/*default diagnostic listener*/, null/*standard doclet*/, options, jfos);
+		DocumentationTool docTool = ToolProvider.getSystemDocumentationTool();
+		StandardJavaFileManager fileManager = docTool.getStandardFileManager(null, null, null);
+		Iterable<? extends JavaFileObject> fileObjects = fileManager.getJavaFileObjects(files.toArray(new String[0]));
+		DocumentationTask task = docTool.getTask(
+			null, // default output writer (System.err)
+			null, // default file manager
+			null, // default diagnostic listener
+			null, // default doclet class
+			options,
+			fileObjects
+		);
 		task.call();
 	}
 }

ajdoc/src/main/java/org/aspectj/tools/ajdoc/Main.java

@@ -22,12 +22,20 @@ import java.io.FileOutputStream;
 import java.io.FileReader;
 import java.io.FilenameFilter;
 import java.io.IOException;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.Hashtable;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.StringTokenizer;
+import java.util.Vector;
 
 import org.aspectj.asm.AsmManager;
 import org.aspectj.bridge.IMessage;
 import org.aspectj.bridge.Version;
 import org.aspectj.util.FileUtil;
+import org.aspectj.util.LangUtil;
 
 /**
  * This is an old implementation of ajdoc that does not use an OO style. However, it does the job, and should serve to evolve a
@@ -256,8 +264,10 @@ public class Main implements Config {
 			for (int k = 0; k < fileList.size(); k++) {
 				javadocargs[numExtraArgs + options.size() + packageList.size() + k] = fileList.elementAt(k);
 			}
+			if (LangUtil.is9VMOrGreater()) {
 			options = new Vector<>();
 			Collections.addAll(options, javadocargs);
+			}
 		} else {
 			javadocargs = new String[options.size() + signatureFiles.length];
 			for (int k = 0; k < options.size(); k++) {
@@ -270,7 +280,11 @@ public class Main implements Config {
 				files.add(StructureUtil.translateAjPathName(signatureFile.getCanonicalPath()));
 			}
 		}
+		if (LangUtil.is9VMOrGreater()) {
 		JavadocRunner.callJavadocViaToolProvider(options, files);
+		} else {
+			JavadocRunner.callJavadoc(javadocargs);
+		}
 	}
 
 	/**