This adds a new 1.6 class, CompositeDataInvocationHandler to javax.management.openmbean.
Changelog:
2007-03-30 Andrew John Hughes <[EMAIL PROTECTED]>
* javax/management/openmbean/CompositeDataInvocationHandler.java:
New file.
--
Andrew :-)
Escape the Java Trap with GNU Classpath!
http://www.gnu.org/philosophy/java-trap.html
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Index: javax/management/openmbean/CompositeDataInvocationHandler.java
===================================================================
RCS file: javax/management/openmbean/CompositeDataInvocationHandler.java
diff -N javax/management/openmbean/CompositeDataInvocationHandler.java
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ javax/management/openmbean/CompositeDataInvocationHandler.java 30 Mar 2007 21:23:29 -0000
@@ -0,0 +1,190 @@
+/* CompositeDataInvocationHandler.java - Pseudo-accessors for CompositeData.
+ Copyright (C) 2007 Free Software Foundation
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING. If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library. Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module. An independent module is a module which is not derived from
+or based on this library. If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so. If you do not wish to do so, delete this
+exception statement from your version. */
+
+package javax.management.openmbean;
+
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+
+/**
+ * <p>
+ * Provides an [EMAIL PROTECTED] java.lang.reflect.InvocationHandler} which
+ * implements a series of accessor methods (those beginning with
+ * [EMAIL PROTECTED] "get"} or [EMAIL PROTECTED] "is"}) using the content of a
+ * [EMAIL PROTECTED] CompositeData} object. An instance of [EMAIL PROTECTED] CompositeData}
+ * consists of a series of key-value mappings. This handler assumes
+ * these keys to be the names of attributes, and thus provides
+ * accessor methods by returning the associated value.
+ * </p>
+ * <p>
+ * As an example, consider the following interface:
+ * </p>
+ * <pre>
+ * public interface Person
+ * {
+ * public String getName();
+ * public Date getBirthday();
+ * }
+ * </pre>
+ * <p>
+ * This specifies two accessor methods for retrieving the attributes,
+ * [EMAIL PROTECTED] name} and [EMAIL PROTECTED] birthday}. An implementation of this interface
+ * can be provided by creating an instance of this class, using a
+ * [EMAIL PROTECTED] CompositeData} object with appropriate key-value mappings
+ * (e.g. "name" => "Fred", "birthday" => 30/06/1974), and then passing
+ * that to [EMAIL PROTECTED] java.lang.reflect.Proxy#newProxyInstance} along with
+ * the interface itself. The invocation handler implements the methods
+ * by calling [EMAIL PROTECTED] CompositeData#get(String)} with the appropriate key.
+ * </p>
+ * <p>
+ * The attribute name is derived by taking the remainder of the method
+ * name following [EMAIL PROTECTED] "get"}. If the first letter of this substring
+ * is uppercase, then two attempts are made to retrieve the attribute
+ * from the [EMAIL PROTECTED] CompositeData} instance: one using the original substring,
+ * and one with the first letter changed to its lower-case equivalent.
+ * If the first letter is lowercase, only the exact substring is used.
+ * </p>
+ * <p>
+ * An [EMAIL PROTECTED] Object#equals(Object)} implementation is provided. This returns
+ * true if the argument is a proxy with a [EMAIL PROTECTED] CompositeDataInvocationHandler}
+ * using an equivalent [EMAIL PROTECTED] CompositeData} instance. [EMAIL PROTECTED] Object#hashCode()}
+ * is also defined so as to match this implementation and give equivalent instances
+ * the same hashcode.
+ * </p>
+ *
+ * @author Andrew John Hughes ([EMAIL PROTECTED])
+ * @since 1.6
+ */
+public class CompositeDataInvocationHandler
+ implements InvocationHandler
+{
+
+ /**
+ * The [EMAIL PROTECTED] CompositeData} providing the key-value mappings.
+ */
+ private CompositeData data;
+
+ /**
+ * Constructs a new [EMAIL PROTECTED] CompositeDataInvocationHandler}
+ * with the specified [EMAIL PROTECTED] CompositeData} instance.
+ *
+ * @param data the [EMAIL PROTECTED] CompositeData} instance to use.
+ * @throws IllegalArgumentException if [EMAIL PROTECTED] data} is [EMAIL PROTECTED] null}.
+ */
+ public CompositeDataInvocationHandler(CompositeData data)
+ {
+ if (data == null)
+ throw new IllegalArgumentException("The CompositeData instance " +
+ "must be non-null.");
+ this.data = data;
+ }
+
+ /**
+ * Returns the [EMAIL PROTECTED] CompositeData} instance which provides
+ * the key-value mappings for this instance. This is never
+ * [EMAIL PROTECTED] null}.
+ *
+ * @return the [EMAIL PROTECTED] CompositeData} instance.
+ */
+ public CompositeData getCompositeData()
+ {
+ return data;
+ }
+
+ /**
+ * Called by the proxy class whenever a method is called. The
+ * handler only deals with accessor methods (beginning with
+ * [EMAIL PROTECTED] "get"} or [EMAIL PROTECTED] "is"}), [EMAIL PROTECTED] equals}, and
+ * [EMAIL PROTECTED] "hashCode"}. Accessor methods are implemented by
+ * returning the appropriate value from the [EMAIL PROTECTED] CompositeData}
+ * instance, while [EMAIL PROTECTED] equals} and [EMAIL PROTECTED] hashCode} allow
+ * two proxies with a [EMAIL PROTECTED] CompositeDataInvocationHandler} using
+ * the same [EMAIL PROTECTED] CompositeData} instance to be classified
+ * as equivalent.
+ *
+ * @param proxy the proxy on which the method was called.
+ * @param method the method which was called.
+ * @param args the arguments supplied to the method.
+ * @return the return value from the method.
+ * @throws Throwable if an exception is thrown in the process.
+ */
+ public Object invoke(Object proxy, Method method, Object[] args)
+ throws Throwable
+ {
+ String mName = method.getName();
+ if (mName.equals("equals"))
+ {
+ if (args[0] instanceof Proxy)
+ {
+ InvocationHandler h = Proxy.getInvocationHandler(args[0]);
+ if (h instanceof CompositeDataInvocationHandler)
+ return data.equals(((CompositeDataInvocationHandler)
+ h).getCompositeData());
+ }
+ return false;
+ }
+ if (mName.equals("hashCode"))
+ {
+ return data.hashCode();
+ }
+ String attrib = null;
+ if (mName.startsWith("get"))
+ attrib = mName.substring(3);
+ else if (mName.startsWith("is"))
+ attrib = mName.substring(2);
+ if (attrib == null)
+ throw new NoSuchMethodException(mName + " is not an accessor.");
+ if (!data.containsKey(attrib))
+ {
+ if (Character.isLowerCase(attrib.charAt(0)))
+ throw new NoSuchMethodException("The attribute " +
+ attrib + " is not available " +
+ "in the given CompositeData " +
+ "object");
+ attrib = Character.toLowerCase(attrib.charAt(0))
+ + attrib.substring(1);
+ if (!data.containsKey(attrib))
+ throw new NoSuchMethodException("The attribute " +
+ attrib + " is not available " +
+ "in the given CompositeData " +
+ "object");
+ }
+ return data.get(attrib);
+ }
+
+}
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