Add XDataManager.isSupported(String)

also make FormField and Option implement NamedElement and some other
minor changes to data form API.

smack-extensions/src/main/java/org/jivesoftware/smackx/xdata/FormField.java

@@ -21,6 +21,7 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 
+import org.jivesoftware.smack.packet.NamedElement;
 import org.jivesoftware.smack.util.XmlStringBuilder;
 import org.jivesoftware.smackx.xdatavalidation.packet.ValidateElement;
 
@@ -31,7 +32,7 @@ import org.jivesoftware.smackx.xdatavalidation.packet.ValidateElement;
  *
  * @author Gaston Dombiak
  */
-public class FormField {
+public class FormField implements NamedElement {
 
     public static final String ELEMENT = "field";
 
@@ -343,9 +344,13 @@ public class FormField {
         }
     }
 
+    @Override
+    public String getElementName() {
+        return ELEMENT;
+    }
+
     public XmlStringBuilder toXML() {
-        XmlStringBuilder buf = new XmlStringBuilder();
-        buf.halfOpenElement(ELEMENT);
+        XmlStringBuilder buf = new XmlStringBuilder(this);
         // Add attributes
         buf.optAttribute("label", getLabel());
         buf.optAttribute("var", getVariable());
@@ -363,7 +368,7 @@ public class FormField {
             buf.append(option.toXML());
         }
         buf.optElement(validateElement);
-        buf.closeElement(ELEMENT);
+        buf.closeElement(this);
         return buf;
     }
 
@@ -391,7 +396,7 @@ public class FormField {
      *
      * @author Gaston Dombiak
      */
-    public static class Option {
+    public static class Option implements NamedElement {
 
         public static final String ELEMENT = "option";
 
@@ -430,9 +435,13 @@ public class FormField {
             return getLabel();
         }
 
+        @Override
+        public String getElementName() {
+            return ELEMENT;
+        }
+
         public XmlStringBuilder toXML() {
-            XmlStringBuilder xml = new XmlStringBuilder();
-            xml.halfOpenElement(ELEMENT);
+            XmlStringBuilder xml = new XmlStringBuilder(this);
             // Add attribute
             xml.optAttribute("label", getLabel());
             xml.rightAngleBracket();
@@ -440,7 +449,7 @@ public class FormField {
             // Add element
             xml.element("value", getValue());
 
-            xml.closeElement(ELEMENT);
+            xml.closeElement(this);
             return xml;
         }
 

smack-extensions/src/main/java/org/jivesoftware/smackx/xdata/XDataManager.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2014 Florian Schmaus
+ * Copyright 2014-2015 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,22 +16,70 @@
  */
 package org.jivesoftware.smackx.xdata;
 
+import java.util.Map;
+import java.util.WeakHashMap;
+
 import org.jivesoftware.smack.ConnectionCreationListener;
+import org.jivesoftware.smack.Manager;
+import org.jivesoftware.smack.SmackException.NoResponseException;
+import org.jivesoftware.smack.SmackException.NotConnectedException;
 import org.jivesoftware.smack.XMPPConnection;
 import org.jivesoftware.smack.XMPPConnectionRegistry;
+import org.jivesoftware.smack.XMPPException.XMPPErrorException;
 import org.jivesoftware.smackx.disco.ServiceDiscoveryManager;
 import org.jivesoftware.smackx.xdata.packet.DataForm;
 
-public class XDataManager {
+public class XDataManager extends Manager {
+
+    /**
+     * The value of {@link DataForm#NAMESPACE}.
+     */
+    public static final String NAMESPACE = DataForm.NAMESPACE;
 
     static {
         XMPPConnectionRegistry.addConnectionCreationListener(new ConnectionCreationListener() {
             @Override
             public void connectionCreated(XMPPConnection connection) {
-                ServiceDiscoveryManager serviceDiscoveryManager = ServiceDiscoveryManager.getInstanceFor(connection);
-                serviceDiscoveryManager.addFeature(DataForm.NAMESPACE);
+                getInstanceFor(connection);
             }
         });
     }
 
+    private static final Map<XMPPConnection, XDataManager> INSTANCES = new WeakHashMap<>();
+
+    /**
+     * Get the XDataManager for the given XMPP connection.
+     *
+     * @param connection
+     * @return the XDataManager
+     */
+    public static synchronized XDataManager getInstanceFor(XMPPConnection connection) {
+        XDataManager xDataManager = INSTANCES.get(connection);
+        if (xDataManager == null) {
+            xDataManager = new XDataManager(connection);
+            INSTANCES.put(connection, xDataManager);
+        }
+        return xDataManager;
+    }
+
+    private XDataManager(XMPPConnection connection) {
+        super(connection);
+        ServiceDiscoveryManager serviceDiscoveryManager = ServiceDiscoveryManager.getInstanceFor(connection);
+        serviceDiscoveryManager.addFeature(NAMESPACE);
+    }
+
+    /**
+     * Check if the given entity supports data forms.
+     *
+     * @param jid the JID of the entity to check.
+     * @return true if the entity supports data forms.
+     * @throws NoResponseException
+     * @throws XMPPErrorException
+     * @throws NotConnectedException
+     * @see <a href="http://xmpp.org/extensions/xep-0004.html#disco">XEP-0004: Data Forms § 6. Service Discovery</a>
+     * @since 4.1
+     */
+    public boolean isSupported(String jid) throws NoResponseException, XMPPErrorException, NotConnectedException {
+        return ServiceDiscoveryManager.getInstanceFor(connection()).supportsFeature(jid, NAMESPACE);
+    }
 }