+ * MBeanServerConnnection rootConnection = ...;
+ *
+ * // create a view at the local root of the namespace hierarchy.
+ * //
+ * JMXNamespaceView view = new JMXNamespaceView(rootConnection);
+ *
+ * // list all top level namespaces
+ * String[] list = view.list();
+ *
+ * // select one namespace from the list
+ * String whereToGo = ... ;
+ *
+ * // go down to the selected namespace:
+ * view = view.down(whereToGo);
+ * System.out.println("I am now in: " + view.where());
+ * System.out.println("I can see these MBeans:" +
+ * view.getMBeanServerConnection().queryNames(null,null));
+ *
+ * // list sub namespaces in current view ('whereToGo')
+ * list = view.list();
+ * System.out.println("Here are the sub namespaces of "+view.where()+": "+
+ * Arrays.toString(list));
+ *
+ * // go up one level
+ * view = view.up();
+ * System.out.println("I am now back to: " +
+ * (view.isRoot() ? "root namespace" : view.where()));
+ *
+ * @since 1.7
+ */
+public class JMXNamespaceView {
+
+ private static final ObjectName ALL_NAMESPACES;
+ static {
+ try {
+ ALL_NAMESPACES = ObjectName.getInstance("*" +
+ JMXNamespaces.NAMESPACE_SEPARATOR + ":"+
+ JMXNamespace.TYPE_ASSIGNMENT);
+ } catch (MalformedObjectNameException x) {
+ throw new ExceptionInInitializerError(x);
+ }
+ }
+ private static final int NAMESPACE_SEPARATOR_LENGTH =
+ JMXNamespaces.NAMESPACE_SEPARATOR.length();
+
+ private final JMXNamespaceView parent;
+ private final MBeanServerConnection here;
+ private final String where;
+
+ private static MBeanServerConnection checkRoot(MBeanServerConnection root) {
+ if (root == null)
+ throw new IllegalArgumentException(
+ "namespaceRoot: null is not a valid value");
+ return root;
+ }
+
+ /**
+ * Creates a view at the top of a JMX namespace hierarchy.
+ * @param namespaceRoot The {@code MBeanServerConnection} at the
+ * top of the hierarchy.
+ */
+ public JMXNamespaceView(MBeanServerConnection namespaceRoot) {
+ this(null,checkRoot(namespaceRoot),"");
+ }
+
+ // This constructor should remain private. A user can only create
+ // JMXNamespaceView at the top of the hierarchy.
+ // JMXNamespaceView sub nodes are created by their parent nodes.
+ private JMXNamespaceView(JMXNamespaceView parent,
+ MBeanServerConnection here, String where) {
+ this.parent = parent;
+ this.here = here;
+ this.where = where;
+ }
+
+ /**
+ * Returns the path leading to the namespace in this view, from
+ * the top of the hierarchy.
+ * @return The path to the namespace in this view.
+ */
+ public String where() {
+ return where;
+ }
+
+ /**
+ * Lists all direct sub namespaces in this view. The returned strings
+ * do not contain the {@code //} separator.
+ *
+ * @return A list of direct sub name spaces accessible from this
+ * namespace.
+ * @throws IOException if the attempt to list the namespaces fails because
+ * of a communication problem.
+ */
+ public String[] list() throws IOException {
+ final Set+ * JMX.narrowToNamespace(this.root().getMBeanServerConnection(), + * this.where()); + *+ * @return A MBeanServerConnection to the namespace shown by this view. + */ + public MBeanServerConnection getMBeanServerConnection() { + return here; + } + + /** + *
Get the name of the JMXNamespaceMBean handling the namespace shown by + * this view, relative to the root of the hierarchy. If we are at the root + * of the hierarchy, this method returns {@code null}.
+ * + *You can use this method to make a proxy for the JMXNamespaceMBean + * as follows:
+ * + *+ * JMXNamespaceView view = ...; + * ObjectName namespaceMBeanName = view.getJMXNamespaceMBeanName(); + * JMXNamespaceMBean namespaceMBean = JMX.newMBeanProxy( + * view.root().getMBeanServerConnection(), namespaceMBeanName, + * JMXNamespaceMBean.class); + *+ * + * @return The name of the {@code JMXNamespaceMBean} handling the namespace + * shown by this view, or {@code null}. + */ + public ObjectName getJMXNamespaceMBeanName() { + if (parent == null) + return null; + else + return JMXNamespaces.getNamespaceObjectName(where); + } + + @Override + public int hashCode() { + return where.hashCode(); + } + + /** + * Returns true if this object is equal to the given object. The + * two objects are equal if the other object is also a {@code + * JMXNamespaceView} and both objects have the same {@linkplain #root root} + * MBeanServerConnection and the same {@linkplain #where path}. + * @param o the other object to compare to. + * @return true if both objects are equal. + */ + @Override + public boolean equals(Object o) { + if (o==this) return true; + if (! (o instanceof JMXNamespaceView)) return false; + if (!where.equals(((JMXNamespaceView)o).where)) return false; + return root().getMBeanServerConnection().equals( + ((JMXNamespaceView)o).root().getMBeanServerConnection()); + } + + private JMXNamespaceView makeJMXNamespaceView(final JMXNamespaceView root, + final JMXNamespaceView directParent, final String pathFromRoot) { + if (pathFromRoot.equals("")) return root; + + return new JMXNamespaceView(directParent, + narrowToNamespace(root.getMBeanServerConnection(), + pathFromRoot),pathFromRoot); + } + + private MBeanServerConnection narrowToNamespace(MBeanServerConnection root, + String path) { + if (root instanceof MBeanServer) + return JMXNamespaces.narrowToNamespace((MBeanServer)root, path); + return JMXNamespaces.narrowToNamespace(root, path); + } + +}