diff -r 400a4e8accd3 -r bdcef2ef52d2 src/share/classes/com/sun/tools/javadoc/DocletInvoker.java
--- a/src/share/classes/com/sun/tools/javadoc/DocletInvoker.java	Thu Nov 15 19:54:20 2012 -0800
+++ b/src/share/classes/com/sun/tools/javadoc/DocletInvoker.java	Thu Nov 15 23:07:24 2012 -0800
@@ -32,7 +32,12 @@
 import java.net.URL;
 import java.net.URLClassLoader;
 
+import javax.tools.DocumentationTool;
+import javax.tools.JavaFileManager;
+
 import com.sun.javadoc.*;
+import com.sun.tools.javac.file.Locations;
+import com.sun.tools.javac.util.ClientCodeException;
 import com.sun.tools.javac.util.List;
 import static com.sun.javadoc.LanguageVersion.*;
 
@@ -57,6 +62,12 @@
 
     private final Messager messager;
 
+    /**
+     * In API mode, exceptions thrown while calling the doclet are
+     * propagated using ClientCodeException.
+     */
+    private final boolean apiMode;
+
     private static class DocletInvokeException extends Exception {
         private static final long serialVersionUID = 0;
     }
@@ -71,24 +82,38 @@
         }
     }
 
-    public DocletInvoker(Messager messager,
+    public DocletInvoker(Messager messager, Class<?> docletClass, boolean apiMode) {
+        this.messager = messager;
+        this.docletClass = docletClass;
+        docletClassName = docletClass.getName();
+        appClassLoader = null;
+        this.apiMode = apiMode;
+    }
+
+    public DocletInvoker(Messager messager, JavaFileManager fileManager,
                          String docletClassName, String docletPath,
-                         ClassLoader docletParentClassLoader) {
+                         ClassLoader docletParentClassLoader,
+                         boolean apiMode) {
         this.messager = messager;
         this.docletClassName = docletClassName;
+        this.apiMode = apiMode;
 
-        // construct class loader
-        String cpString = null;   // make sure env.class.path defaults to dot
+        if (fileManager != null && fileManager.hasLocation(DocumentationTool.Location.DOCLET_PATH)) {
+            appClassLoader = fileManager.getClassLoader(DocumentationTool.Location.DOCLET_PATH);
+        } else {
+            // construct class loader
+            String cpString = null;   // make sure env.class.path defaults to dot
 
-        // do prepends to get correct ordering
-        cpString = appendPath(System.getProperty("env.class.path"), cpString);
-        cpString = appendPath(System.getProperty("java.class.path"), cpString);
-        cpString = appendPath(docletPath, cpString);
-        URL[] urls = com.sun.tools.javac.file.Locations.pathToURLs(cpString);
-        if (docletParentClassLoader == null)
-            appClassLoader = new URLClassLoader(urls, getDelegationClassLoader(docletClassName));
-        else
-            appClassLoader = new URLClassLoader(urls, docletParentClassLoader);
+            // do prepends to get correct ordering
+            cpString = appendPath(System.getProperty("env.class.path"), cpString);
+            cpString = appendPath(System.getProperty("java.class.path"), cpString);
+            cpString = appendPath(docletPath, cpString);
+            URL[] urls = Locations.pathToURLs(cpString);
+            if (docletParentClassLoader == null)
+                appClassLoader = new URLClassLoader(urls, getDelegationClassLoader(docletClassName));
+            else
+                appClassLoader = new URLClassLoader(urls, docletParentClassLoader);
+        }
 
         // attempt to find doclet
         Class<?> dc = null;
@@ -280,7 +305,8 @@
             ClassLoader savedCCL =
                 Thread.currentThread().getContextClassLoader();
             try {
-                Thread.currentThread().setContextClassLoader(appClassLoader);
+                if (appClassLoader != null) // will be null if doclet class provided via API
+                    Thread.currentThread().setContextClassLoader(appClassLoader);
                 return meth.invoke(null , params);
             } catch (IllegalArgumentException exc) {
                 messager.error(Messager.NOPOS, "main.internal_error_exception_thrown",
@@ -296,10 +322,12 @@
                 throw new DocletInvokeException();
             } catch (InvocationTargetException exc) {
                 Throwable err = exc.getTargetException();
+                if (apiMode)
+                    throw new ClientCodeException(err);
                 if (err instanceof java.lang.OutOfMemoryError) {
                     messager.error(Messager.NOPOS, "main.out.of.memory");
                 } else {
-                messager.error(Messager.NOPOS, "main.exception_thrown",
+                    messager.error(Messager.NOPOS, "main.exception_thrown",
                                docletClassName, methodName, exc.toString());
                     exc.getTargetException().printStackTrace();
                 }