Java example source code file (MXBeanProxy.java)

This example Java source code file (MXBeanProxy.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

attribute, convertingmethod, exception, gethandler, handler, invokehandler, management, mxbeanlookup, mxbeanproxy, object, objectname, override, reflection, sethandler, string, util, visitor

The MXBeanProxy.java Java example source code

/*
 * Copyright (c) 2005, 2008, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package com.sun.jmx.mbeanserver;

import static com.sun.jmx.mbeanserver.Util.*;

import java.lang.reflect.Method;
import java.util.Map;

import javax.management.Attribute;
import javax.management.MBeanServerConnection;
import javax.management.NotCompliantMBeanException;
import javax.management.ObjectName;

/**
   <p>Helper class for an {@link InvocationHandler} that forwards methods from an
   MXBean interface to a named
   MXBean in an MBean Server and handles translation between the
   arbitrary Java types in the interface and the Open Types used
   by the MXBean.</p>

   @since 1.6
*/
public class MXBeanProxy {
    public MXBeanProxy(Class<?> mxbeanInterface) {

        if (mxbeanInterface == null)
            throw new IllegalArgumentException("Null parameter");

        final MBeanAnalyzer<ConvertingMethod> analyzer;
        try {
            analyzer =
                MXBeanIntrospector.getInstance().getAnalyzer(mxbeanInterface);
        } catch (NotCompliantMBeanException e) {
            throw new IllegalArgumentException(e);
        }
        analyzer.visit(new Visitor());
    }

    private class Visitor
            implements MBeanAnalyzer.MBeanVisitor<ConvertingMethod> {
        public void visitAttribute(String attributeName,
                                   ConvertingMethod getter,
                                   ConvertingMethod setter) {
            if (getter != null) {
                getter.checkCallToOpen();
                Method getterMethod = getter.getMethod();
                handlerMap.put(getterMethod,
                               new GetHandler(attributeName, getter));
            }
            if (setter != null) {
                // return type is void, no need for checkCallToOpen
                Method setterMethod = setter.getMethod();
                handlerMap.put(setterMethod,
                               new SetHandler(attributeName, setter));
            }
        }

        public void visitOperation(String operationName,
                                   ConvertingMethod operation) {
            operation.checkCallToOpen();
            Method operationMethod = operation.getMethod();
            String[] sig = operation.getOpenSignature();
            handlerMap.put(operationMethod,
                           new InvokeHandler(operationName, sig, operation));
        }
    }

    private static abstract class Handler {
        Handler(String name, ConvertingMethod cm) {
            this.name = name;
            this.convertingMethod = cm;
        }

        String getName() {
            return name;
        }

        ConvertingMethod getConvertingMethod() {
            return convertingMethod;
        }

        abstract Object invoke(MBeanServerConnection mbsc,
                               ObjectName name, Object[] args) throws Exception;

        private final String name;
        private final ConvertingMethod convertingMethod;
    }

    private static class GetHandler extends Handler {
        GetHandler(String attributeName, ConvertingMethod cm) {
            super(attributeName, cm);
        }

        @Override
        Object invoke(MBeanServerConnection mbsc, ObjectName name, Object[] args)
                throws Exception {
            assert(args == null || args.length == 0);
            return mbsc.getAttribute(name, getName());
        }
    }

    private static class SetHandler extends Handler {
        SetHandler(String attributeName, ConvertingMethod cm) {
            super(attributeName, cm);
        }

        @Override
        Object invoke(MBeanServerConnection mbsc, ObjectName name, Object[] args)
                throws Exception {
            assert(args.length == 1);
            Attribute attr = new Attribute(getName(), args[0]);
            mbsc.setAttribute(name, attr);
            return null;
        }
    }

    private static class InvokeHandler extends Handler {
        InvokeHandler(String operationName, String[] signature,
                      ConvertingMethod cm) {
            super(operationName, cm);
            this.signature = signature;
        }

        Object invoke(MBeanServerConnection mbsc, ObjectName name, Object[] args)
                throws Exception {
            return mbsc.invoke(name, getName(), args, signature);
        }

        private final String[] signature;
    }

    public Object invoke(MBeanServerConnection mbsc, ObjectName name,
                         Method method, Object[] args)
            throws Throwable {

        Handler handler = handlerMap.get(method);
        ConvertingMethod cm = handler.getConvertingMethod();
        MXBeanLookup lookup = MXBeanLookup.lookupFor(mbsc);
        MXBeanLookup oldLookup = MXBeanLookup.getLookup();
        try {
            MXBeanLookup.setLookup(lookup);
            Object[] openArgs = cm.toOpenParameters(lookup, args);
            Object result = handler.invoke(mbsc, name, openArgs);
            return cm.fromOpenReturnValue(lookup, result);
        } finally {
            MXBeanLookup.setLookup(oldLookup);
        }
    }

    private final Map<Method, Handler> handlerMap = newMap();
}