/*
* Copyright (c) 2002, 2013, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
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*/
package javax.management;
import com.sun.jmx.mbeanserver.
MXBeanProxy;
import java.lang.ref.
WeakReference;
import java.lang.reflect.
InvocationHandler;
import java.lang.reflect.
Method;
import java.lang.reflect.
Proxy;
import java.util.
Arrays;
import java.util.
WeakHashMap;
/**
* <p>{@link InvocationHandler} that forwards methods in an MBean's
* management interface through the MBean server to the MBean.</p>
*
* <p>Given an {@link MBeanServerConnection}, the {@link ObjectName}
* of an MBean within that MBean server, and a Java interface
* <code>Intf</code> that describes the management interface of the
* MBean using the patterns for a Standard MBean or an MXBean, this
* class can be used to construct a proxy for the MBean. The proxy
* implements the interface <code>Intf</code> such that all of its
* methods are forwarded through the MBean server to the MBean.</p>
*
* <p>If the {@code InvocationHandler} is for an MXBean, then the parameters of
* a method are converted from the type declared in the MXBean
* interface into the corresponding mapped type, and the return value
* is converted from the mapped type into the declared type. For
* example, with the method<br>
* {@code public List<String> reverse(List<String> list);}<br>
* and given that the mapped type for {@code List<String>} is {@code
* String[]}, a call to {@code proxy.reverse(someList)} will convert
* {@code someList} from a {@code List<String>} to a {@code String[]},
* call the MBean operation {@code reverse}, then convert the returned
* {@code String[]} into a {@code List<String>}.</p>
*
* <p>The method Object.toString(), Object.hashCode(), or
* Object.equals(Object), when invoked on a proxy using this
* invocation handler, is forwarded to the MBean server as a method on
* the proxied MBean only if it appears in one of the proxy's
* interfaces. For a proxy created with {@link
* JMX#newMBeanProxy(MBeanServerConnection, ObjectName, Class)
* JMX.newMBeanProxy} or {@link
* JMX#newMXBeanProxy(MBeanServerConnection, ObjectName, Class)
* JMX.newMXBeanProxy}, this means that the method must appear in the
* Standard MBean or MXBean interface. Otherwise these methods have
* the following behavior:
* <ul>
* <li>toString() returns a string representation of the proxy
* <li>hashCode() returns a hash code for the proxy such
* that two equal proxies have the same hash code
* <li>equals(Object)
* returns true if and only if the Object argument is of the same
* proxy class as this proxy, with an MBeanServerInvocationHandler
* that has the same MBeanServerConnection and ObjectName; if one
* of the {@code MBeanServerInvocationHandler}s was constructed with
* a {@code Class} argument then the other must have been constructed
* with the same {@code Class} for {@code equals} to return true.
* </ul>
*
* @since 1.5
*/
public class
MBeanServerInvocationHandler implements
InvocationHandler {
/**
* <p>Invocation handler that forwards methods through an MBean
* server to a Standard MBean. This constructor may be called
* instead of relying on {@link
* JMX#newMBeanProxy(MBeanServerConnection, ObjectName, Class)
* JMX.newMBeanProxy}, for instance if you need to supply a
* different {@link ClassLoader} to {@link Proxy#newProxyInstance
* Proxy.newProxyInstance}.</p>
*
* <p>This constructor is not appropriate for an MXBean. Use
* {@link #MBeanServerInvocationHandler(MBeanServerConnection,
* ObjectName, boolean)} for that. This constructor is equivalent
* to {@code new MBeanServerInvocationHandler(connection,
* objectName, false)}.</p>
*
* @param connection the MBean server connection through which all
* methods of a proxy using this handler will be forwarded.
*
* @param objectName the name of the MBean within the MBean server
* to which methods will be forwarded.
*/
public
MBeanServerInvocationHandler(
MBeanServerConnection connection,
ObjectName objectName) {
this(
connection,
objectName, false);
}
/**
* <p>Invocation handler that can forward methods through an MBean
* server to a Standard MBean or MXBean. This constructor may be called
* instead of relying on {@link
* JMX#newMXBeanProxy(MBeanServerConnection, ObjectName, Class)
* JMX.newMXBeanProxy}, for instance if you need to supply a
* different {@link ClassLoader} to {@link Proxy#newProxyInstance
* Proxy.newProxyInstance}.</p>
*
* @param connection the MBean server connection through which all
* methods of a proxy using this handler will be forwarded.
*
* @param objectName the name of the MBean within the MBean server
* to which methods will be forwarded.
*
* @param isMXBean if true, the proxy is for an {@link MXBean}, and
* appropriate mappings will be applied to method parameters and return
* values.
*
* @since 1.6
*/
public
MBeanServerInvocationHandler(
MBeanServerConnection connection,
ObjectName objectName,
boolean
isMXBean) {
if (
connection == null) {
throw new
IllegalArgumentException("Null connection");
}
if (
Proxy.
isProxyClass(
connection.
getClass())) {
if (
MBeanServerInvocationHandler.class.
isAssignableFrom(
Proxy.
getInvocationHandler(
connection).
getClass())) {
throw new
IllegalArgumentException("Wrapping MBeanServerInvocationHandler");
}
}
if (
objectName == null) {
throw new
IllegalArgumentException("Null object name");
}
this.
connection =
connection;
this.
objectName =
objectName;
this.
isMXBean =
isMXBean;
}
/**
* <p>The MBean server connection through which the methods of
* a proxy using this handler are forwarded.</p>
*
* @return the MBean server connection.
*
* @since 1.6
*/
public
MBeanServerConnection getMBeanServerConnection() {
return
connection;
}
/**
* <p>The name of the MBean within the MBean server to which methods
* are forwarded.
*
* @return the object name.
*
* @since 1.6
*/
public
ObjectName getObjectName() {
return
objectName;
}
/**
* <p>If true, the proxy is for an MXBean, and appropriate mappings
* are applied to method parameters and return values.
*
* @return whether the proxy is for an MXBean.
*
* @since 1.6
*/
public boolean
isMXBean() {
return
isMXBean;
}
/**
* <p>Return a proxy that implements the given interface by
* forwarding its methods through the given MBean server to the
* named MBean. As of 1.6, the methods {@link
* JMX#newMBeanProxy(MBeanServerConnection, ObjectName, Class)} and
* {@link JMX#newMBeanProxy(MBeanServerConnection, ObjectName, Class,
* boolean)} are preferred to this method.</p>
*
* <p>This method is equivalent to {@link Proxy#newProxyInstance
* Proxy.newProxyInstance}<code>(interfaceClass.getClassLoader(),
* interfaces, handler)</code>. Here <code>handler</code> is the
* result of {@link #MBeanServerInvocationHandler new
* MBeanServerInvocationHandler(connection, objectName)}, and
* <code>interfaces</code> is an array that has one element if
* <code>notificationBroadcaster</code> is false and two if it is
* true. The first element of <code>interfaces</code> is
* <code>interfaceClass</code> and the second, if present, is
* <code>NotificationEmitter.class</code>.
*
* @param connection the MBean server to forward to.
* @param objectName the name of the MBean within
* <code>connection</code> to forward to.
* @param interfaceClass the management interface that the MBean
* exports, which will also be implemented by the returned proxy.
* @param notificationBroadcaster make the returned proxy
* implement {@link NotificationEmitter} by forwarding its methods
* via <code>connection</code>. A call to {@link
* NotificationBroadcaster#addNotificationListener} on the proxy will
* result in a call to {@link
* MBeanServerConnection#addNotificationListener(ObjectName,
* NotificationListener, NotificationFilter, Object)}, and likewise
* for the other methods of {@link NotificationBroadcaster} and {@link
* NotificationEmitter}.
*
* @param <T> allows the compiler to know that if the {@code
* interfaceClass} parameter is {@code MyMBean.class}, for example,
* then the return type is {@code MyMBean}.
*
* @return the new proxy instance.
*
* @see JMX#newMBeanProxy(MBeanServerConnection, ObjectName, Class, boolean)
*/
public static <T> T
newProxyInstance(
MBeanServerConnection connection,
ObjectName objectName,
Class<T>
interfaceClass,
boolean
notificationBroadcaster) {
return
JMX.
newMBeanProxy(
connection,
objectName,
interfaceClass,
notificationBroadcaster);
}
public
Object invoke(
Object proxy,
Method method,
Object[]
args)
throws
Throwable {
final
Class<?>
methodClass =
method.
getDeclaringClass();
if (
methodClass.
equals(
NotificationBroadcaster.class)
||
methodClass.
equals(
NotificationEmitter.class))
return
invokeBroadcasterMethod(
proxy,
method,
args);
// local or not: equals, toString, hashCode
if (
shouldDoLocally(
proxy,
method))
return
doLocally(
proxy,
method,
args);
try {
if (
isMXBean()) {
MXBeanProxy p =
findMXBeanProxy(
methodClass);
return
p.
invoke(
connection,
objectName,
method,
args);
} else {
final
String methodName =
method.
getName();
final
Class<?>[]
paramTypes =
method.
getParameterTypes();
final
Class<?>
returnType =
method.
getReturnType();
/* Inexplicably, InvocationHandler specifies that args is null
when the method takes no arguments rather than a
zero-length array. */
final int
nargs = (
args == null) ? 0 :
args.length;
if (
methodName.
startsWith("get")
&&
methodName.
length() > 3
&&
nargs == 0
&& !
returnType.
equals(
Void.
TYPE)) {
return
connection.
getAttribute(
objectName,
methodName.
substring(3));
}
if (
methodName.
startsWith("is")
&&
methodName.
length() > 2
&&
nargs == 0
&& (
returnType.
equals(
Boolean.
TYPE)
||
returnType.
equals(
Boolean.class))) {
return
connection.
getAttribute(
objectName,
methodName.
substring(2));
}
if (
methodName.
startsWith("set")
&&
methodName.
length() > 3
&&
nargs == 1
&&
returnType.
equals(
Void.
TYPE)) {
Attribute attr = new
Attribute(
methodName.
substring(3),
args[0]);
connection.
setAttribute(
objectName,
attr);
return null;
}
final
String[]
signature = new
String[
paramTypes.length];
for (int
i = 0;
i <
paramTypes.length;
i++)
signature[
i] =
paramTypes[
i].
getName();
return
connection.
invoke(
objectName,
methodName,
args,
signature);
}
} catch (
MBeanException e) {
throw
e.
getTargetException();
} catch (
RuntimeMBeanException re) {
throw
re.
getTargetException();
} catch (
RuntimeErrorException rre) {
throw
rre.
getTargetError();
}
/* The invoke may fail because it can't get to the MBean, with
one of the these exceptions declared by
MBeanServerConnection.invoke:
- RemoteException: can't talk to MBeanServer;
- InstanceNotFoundException: objectName is not registered;
- ReflectionException: objectName is registered but does not
have the method being invoked.
In all of these cases, the exception will be wrapped by the
proxy mechanism in an UndeclaredThrowableException unless
it happens to be declared in the "throws" clause of the
method being invoked on the proxy.
*/
}
private static
MXBeanProxy findMXBeanProxy(
Class<?>
mxbeanInterface) {
synchronized (
mxbeanProxies) {
WeakReference<
MXBeanProxy>
proxyRef =
mxbeanProxies.
get(
mxbeanInterface);
MXBeanProxy p = (
proxyRef == null) ? null :
proxyRef.
get();
if (
p == null) {
try {
p = new
MXBeanProxy(
mxbeanInterface);
} catch (
IllegalArgumentException e) {
String msg = "Cannot make MXBean proxy for " +
mxbeanInterface.
getName() + ": " +
e.
getMessage();
IllegalArgumentException iae =
new
IllegalArgumentException(
msg,
e.
getCause());
iae.
setStackTrace(
e.
getStackTrace());
throw
iae;
}
mxbeanProxies.
put(
mxbeanInterface,
new
WeakReference<
MXBeanProxy>(
p));
}
return
p;
}
}
private static final
WeakHashMap<
Class<?>,
WeakReference<
MXBeanProxy>>
mxbeanProxies = new
WeakHashMap<
Class<?>,
WeakReference<
MXBeanProxy>>();
private
Object invokeBroadcasterMethod(
Object proxy,
Method method,
Object[]
args) throws
Exception {
final
String methodName =
method.
getName();
final int
nargs = (
args == null) ? 0 :
args.length;
if (
methodName.
equals("addNotificationListener")) {
/* The various throws of IllegalArgumentException here
should not happen, since we know what the methods in
NotificationBroadcaster and NotificationEmitter
are. */
if (
nargs != 3) {
final
String msg =
"Bad arg count to addNotificationListener: " +
nargs;
throw new
IllegalArgumentException(
msg);
}
/* Other inconsistencies will produce ClassCastException
below. */
NotificationListener listener = (
NotificationListener)
args[0];
NotificationFilter filter = (
NotificationFilter)
args[1];
Object handback =
args[2];
connection.
addNotificationListener(
objectName,
listener,
filter,
handback);
return null;
} else if (
methodName.
equals("removeNotificationListener")) {
/* NullPointerException if method with no args, but that
shouldn't happen because removeNL does have args. */
NotificationListener listener = (
NotificationListener)
args[0];
switch (
nargs) {
case 1:
connection.
removeNotificationListener(
objectName,
listener);
return null;
case 3:
NotificationFilter filter = (
NotificationFilter)
args[1];
Object handback =
args[2];
connection.
removeNotificationListener(
objectName,
listener,
filter,
handback);
return null;
default:
final
String msg =
"Bad arg count to removeNotificationListener: " +
nargs;
throw new
IllegalArgumentException(
msg);
}
} else if (
methodName.
equals("getNotificationInfo")) {
if (
args != null) {
throw new
IllegalArgumentException("getNotificationInfo has " +
"args");
}
MBeanInfo info =
connection.
getMBeanInfo(
objectName);
return
info.
getNotifications();
} else {
throw new
IllegalArgumentException("Bad method name: " +
methodName);
}
}
private boolean
shouldDoLocally(
Object proxy,
Method method) {
final
String methodName =
method.
getName();
if ((
methodName.
equals("hashCode") ||
methodName.
equals("toString"))
&&
method.
getParameterTypes().length == 0
&&
isLocal(
proxy,
method))
return true;
if (
methodName.
equals("equals")
&&
Arrays.
equals(
method.
getParameterTypes(),
new
Class<?>[] {
Object.class})
&&
isLocal(
proxy,
method))
return true;
if (
methodName.
equals("finalize")
&&
method.
getParameterTypes().length == 0) {
return true;
}
return false;
}
private
Object doLocally(
Object proxy,
Method method,
Object[]
args) {
final
String methodName =
method.
getName();
if (
methodName.
equals("equals")) {
if (this ==
args[0]) {
return true;
}
if (!(
args[0] instanceof
Proxy)) {
return false;
}
final
InvocationHandler ihandler =
Proxy.
getInvocationHandler(
args[0]);
if (
ihandler == null ||
!(
ihandler instanceof
MBeanServerInvocationHandler)) {
return false;
}
final
MBeanServerInvocationHandler handler =
(
MBeanServerInvocationHandler)
ihandler;
return
connection.
equals(
handler.
connection) &&
objectName.
equals(
handler.
objectName) &&
proxy.
getClass().
equals(
args[0].
getClass());
} else if (
methodName.
equals("toString")) {
return (
isMXBean() ? "MX" : "M") + "BeanProxy(" +
connection + "[" +
objectName + "])";
} else if (
methodName.
equals("hashCode")) {
return
objectName.
hashCode()+
connection.
hashCode();
} else if (
methodName.
equals("finalize")) {
// ignore the finalizer invocation via proxy
return null;
}
throw new
RuntimeException("Unexpected method name: " +
methodName);
}
private static boolean
isLocal(
Object proxy,
Method method) {
final
Class<?>[]
interfaces =
proxy.
getClass().
getInterfaces();
if(
interfaces == null) {
return true;
}
final
String methodName =
method.
getName();
final
Class<?>[]
params =
method.
getParameterTypes();
for (
Class<?>
intf :
interfaces) {
try {
intf.
getMethod(
methodName,
params);
return false; // found method in one of our interfaces
} catch (
NoSuchMethodException nsme) {
// OK.
}
}
return true; // did not find in any interface
}
private final
MBeanServerConnection connection;
private final
ObjectName objectName;
private final boolean
isMXBean;
}