[SPARK-9261] [streaming] Avoid calling APIs that expose shaded classes.

core/src/main/scala/org/apache/spark/ui/WebUI.scala

@@ -107,6 +107,25 @@ private[spark] abstract class WebUI(
     }
   }
 
+  /**
+   * Add a handler for static content.
+   *
+   * @param resourceBase Root of where to find resources to serve.
+   * @param path Path in UI where to mount the resources.
+   */
+  def addStaticHandler(resourceBase: String, path: String): Unit = {
+    attachHandler(JettyUtils.createStaticHandler(resourceBase, path))
+  }
+
+  /**
+   * Remove a static content handler.
+   *
+   * @param path Path in UI to unmount.
+   */
+  def removeStaticHandler(path: String): Unit = {
+    handlers.find(_.getContextPath() == path).foreach(detachHandler)
+  }
+
   /** Initialize all components of the server. */
   def initialize()
 

streaming/src/main/scala/org/apache/spark/streaming/ui/StreamingTab.scala

@@ -17,11 +17,9 @@
 
 package org.apache.spark.streaming.ui
 
-import org.eclipse.jetty.servlet.ServletContextHandler
-
 import org.apache.spark.{Logging, SparkException}
 import org.apache.spark.streaming.StreamingContext
-import org.apache.spark.ui.{JettyUtils, SparkUI, SparkUITab}
+import org.apache.spark.ui.{SparkUI, SparkUITab}
 
 import StreamingTab._
 
@@ -42,18 +40,14 @@ private[spark] class StreamingTab(val ssc: StreamingContext)
   attachPage(new StreamingPage(this))
   attachPage(new BatchPage(this))
 
-  var staticHandler: ServletContextHandler = null
-
   def attach() {
     getSparkUI(ssc).attachTab(this)
-    staticHandler = JettyUtils.createStaticHandler(STATIC_RESOURCE_DIR, "/static/streaming")
-    getSparkUI(ssc).attachHandler(staticHandler)
+    getSparkUI(ssc).addStaticHandler(STATIC_RESOURCE_DIR, "/static/streaming")
   }
 
   def detach() {
     getSparkUI(ssc).detachTab(this)
-    getSparkUI(ssc).detachHandler(staticHandler)
-    staticHandler = null
+    getSparkUI(ssc).removeStaticHandler("/static/streaming")
   }
 }