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public class MLet extends URLClassLoader implements MLetMBean, MBeanRegistration, Externalizable
Allows you to instantiate and register one or several MBeans in the MBean server coming from a remote URL. M-let is a shortcut for management applet. The m-let service does this by loading an m-let text file, which specifies information on the MBeans to be obtained. The information on each MBean is specified in a single instance of a tag, called the MLET tag. The location of the m-let text file is specified by a URL.
The MLET
tag has the following syntax:
<MLET
CODE =
class | OBJECT =
serfile
ARCHIVE = "
archiveList"
[CODEBASE =
codebaseURL]
[NAME =
mbeanname]
[VERSION =
version]
>
[
arglist]
</MLET
>
where:
CODE =
class.class
file of the MBean must be contained in one of the .jar
files specified by the ARCHIVE
attribute. Either CODE
or OBJECT
must be present.
OBJECT =
serfile.ser
file that contains a serialized representation of the MBean to be obtained.
This file must be contained in one of the .jar
files specified by the ARCHIVE
attribute. If the .jar
file contains a directory hierarchy, specify the path of the file within this hierarchy. Otherwise a match will not be found. Either CODE
or OBJECT
must be present.
ARCHIVE = "
archiveList"
.jar
files
containing MBeans or other resources used by
the MBean to be obtained. One of the .jar
files must contain the file specified by the CODE
or OBJECT
attribute.
If archivelist contains more than one file:
.jar
files in archivelist must be stored in the directory specified by the code base URL.
CODEBASE =
codebaseURL.jar
files specified by the ARCHIVE
attribute. Specify this attribute only if the .jar
files are not in the same
directory as the m-let text file. If this attribute is not specified, the base URL of the m-let text file is used.
NAME =
mbeannameVERSION =
version.jar
files to be obtained. This version number can
be used to specify that the .jar
files are loaded from the
server to update those stored locally in the cache the next time the m-let
text file is loaded. version must be a series of non-negative
decimal integers each separated by a period from the one that precedes it.
ARG TYPE=
argumentType VALUE=
value>
The arguments' type in the argument list should be a Java primitive type or a Java basic type
(java.lang.Boolean, java.lang.Byte, java.lang.Short, java.lang.Long, java.lang.Integer, java.lang.Float, java.lang.Double, java.lang.String
).
The m-let service extends the java.net.URLClassLoader
and can be used to load remote classes
and jar files in the VM of the agent.
Note - The MLet
class loader uses the {@link javax.management.MBeanServerFactory#getClassLoaderRepository(javax.management.MBeanServer)}
to load classes that could not be found in the loaded jar files.
Constructor Summary | |
---|---|
MLet() Constructs a new MLet using the default delegation parent ClassLoader. |
|
Constructs a new MLet for the specified URLs using the default delegation parent ClassLoader. |
|
Constructs a new MLet for the specified URLs using the default delegation parent ClassLoader. |
|
MLet(URL[] urls, ClassLoader parent) Constructs a new MLet for the given URLs. |
|
MLet(URL[] urls, ClassLoader parent, boolean delegateToCLR) Constructs a new MLet for the given URLs. |
|
MLet(URL[] urls, ClassLoader parent, URLStreamHandlerFactory factory) Constructs a new MLet for the specified URLs, parent class loader, and URLStreamHandlerFactory. |
|
MLet(URL[] urls, ClassLoader parent, URLStreamHandlerFactory factory, boolean delegateToCLR) Constructs a new MLet for the specified URLs, parent class loader, and URLStreamHandlerFactory. |
Method Summary | |
---|---|
void |
Appends the specified URL to the list of URLs to search for classes and resources. |
void |
Appends the specified URL to the list of URLs to search for classes and resources. |
protected URL |
check(String version, URL codebase, String jarfile, MLetContent mlet) This method is to be overridden when extending this service to support caching and versioning. |
protected Class |
This is the main method for class loaders that is being redefined. |
protected String |
findLibrary(String libname) Returns the absolute path name of a native library. |
String |
Gets the current directory used by the library loader for storing native libraries before they are loaded into memory. |
Set |
getMBeansFromURL(String url) Loads a text file containing MLET tags that define the MBeans to be added to the MBean server. |
Set |
getMBeansFromURL(URL url) Loads a text file containing MLET tags that define the MBeans to be added to the MBean server. |
URL[] |
getURLs() Returns the search path of URLs for loading classes and resources. |
Class |
loadClass(String name, ClassLoaderRepository clr) Load a class, using the given javax.management.loading.ClassLoaderRepository if the class is not found in this MLet's URLs. |
void |
Allows the m-let to perform any operations needed after having been unregistered in the MBean server. |
void |
postRegister(Boolean registrationDone) Allows the m-let to perform any operations needed after having been registered in the MBean server or after the registration has failed. |
void |
Allows the m-let to perform any operations it needs before being unregistered by the MBean server. |
ObjectName |
preRegister(MBeanServer server, ObjectName name) Allows the m-let to perform any operations it needs before being registered in the MBean server. |
void |
Restore this MLet's contents from the given java.io.ObjectInput. |
void |
setLibraryDirectory(String libdir) Sets the directory used by the library loader for storing native libraries before they are loaded into memory. |
void |
Save this MLet's contents to the given java.io.ObjectOutput. |
Methods inherited from class java.net.URLClassLoader |
---|
addURL, definePackage, findClass, findResource, findResources, getPermissions, getURLs, newInstance, newInstance |
Methods inherited from class java.security.SecureClassLoader |
---|
defineClass, defineClass, getPermissions |
Methods inherited from class java.lang.Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
---|
public MLet()
public MLet(URL[] urls)
urls
- The URLs from which to load classes and resources.public MLet(URL[] urls, boolean delegateToCLR)
urls
- The URLs from which to load classes and resources.delegateToCLR
- True if, when a class is not found in
either the parent ClassLoader or the URLs, the MLet should delegate
to its containing MBeanServer's {@link ClassLoaderRepository}.public MLet(URL[] urls, ClassLoader parent)
urls
- The URLs from which to load classes and resources.parent
- The parent class loader for delegation.public MLet(URL[] urls, ClassLoader parent, boolean delegateToCLR)
urls
- The URLs from which to load classes and resources.parent
- The parent class loader for delegation.delegateToCLR
- True if, when a class is not found in
either the parent ClassLoader or the URLs, the MLet should delegate
to its containing MBeanServer's {@link ClassLoaderRepository}.public MLet(URL[] urls, ClassLoader parent, URLStreamHandlerFactory factory)
urls
- The URLs from which to load classes and resources.parent
- The parent class loader for delegation.factory
- The URLStreamHandlerFactory to use when creating URLs.public MLet(URL[] urls, ClassLoader parent, URLStreamHandlerFactory factory, boolean delegateToCLR)
urls
- The URLs from which to load classes and resources.parent
- The parent class loader for delegation.factory
- The URLStreamHandlerFactory to use when creating URLs.delegateToCLR
- True if, when a class is not found in
either the parent ClassLoader or the URLs, the MLet should delegate
to its containing MBeanServer's {@link ClassLoaderRepository}.Method Detail |
---|
public void addURL(String url) throws ServiceNotFoundException
url
ServiceNotFoundException
- The specified URL is malformed.public void addURL(URL url)
addURL
in class URLClassLoader
url
protected URL check(String version, URL codebase, String jarfile, MLetContent mlet) throws Exception
This method is to be overridden when extending this service to support caching and versioning. It is called from {@link #getMBeansFromURL getMBeansFromURL} when the version, codebase, and jarfile have been extracted from the MLet file, and can be used to verify that it is all right to load the given MBean, or to replace the given URL with a different one.
The default implementation of this method returns
codebase
unchanged.
version
- The version number of the .jar
file stored locally.codebase
- The base URL of the remote .jar
file.jarfile
- The name of the .jar
file to be loaded.mlet
- The MLetContent
instance that
represents the MLET
tag.Exception
- if the MBean is not to be loaded for some
reason. The exception will be added to the set returned by
{@link #getMBeansFromURL getMBeansFromURL}.protected Class findClass(String name) throws ClassNotFoundException
findClass
in class URLClassLoader
name
- The name of the class.ClassNotFoundException
- The specified class could not be
found.protected String findLibrary(String libname)
OSName/OSArch/OSVersion/lib/nativelibname
), i.e.
the library stat on Solaris SPARC 5.7 will be searched in the JAR file as:
More specifically, let {@code nativelibname} be the result of
{@link System#mapLibraryName(java.lang.String)
System.mapLibraryName}{@code (libname)}. Then the following names are
searched in the JAR files, in order:
If this method returns
{@code nativelibname}
{@code
where {@code null
, i.e. the libraries
were not found in any of the JAR files loaded with this class
loader, the VM searches the library along the path specified
as the java.library.path
property.
findLibrary
in class ClassLoader
libname
- The library name.
public synchronized String getLibraryDirectory()
public Set getMBeansFromURL(String url) throws ServiceNotFoundException
url
- The URL of the text file to be loaded as String object.ServiceNotFoundException
- One of the following
errors has occurred: The m-let text file does not contain an
MLET tag, the m-let text file is not found, a mandatory
attribute of the MLET tag is not specified, the url is
malformed.public Set getMBeansFromURL(URL url) throws ServiceNotFoundException
url
- The URL of the text file to be loaded as URL object.ServiceNotFoundException
- One of the following errors has occurred: The m-let text file does
not contain an MLET tag, the m-let text file is not found, a mandatory
attribute of the MLET tag is not specified, the value of url is
null.public URL[] getURLs()
getURLs
in class URLClassLoader
public synchronized Class loadClass(String name, ClassLoaderRepository clr) throws ClassNotFoundException
Load a class, using the given {@link ClassLoaderRepository} if the class is not found in this MLet's URLs. The given ClassLoaderRepository can be null, in which case a {@link ClassNotFoundException} occurs immediately if the class is not found in this MLet's URLs.
name
- The name of the class we want to load.clr
- The ClassLoaderRepository that will be used to search
for the given class, if it is not found in this
ClassLoader. May be null.ClassNotFoundException
- The specified class could not be
found in this ClassLoader nor in the given
ClassLoaderRepository.public void postDeregister()
public void postRegister(Boolean registrationDone)
registrationDone
- Indicates whether or not the m-let has
been successfully registered in the MBean server. The value
false means that either the registration phase has failed.public void preDeregister() throws Exception
Exception
public ObjectName preRegister(MBeanServer server, ObjectName name) throws Exception
server
- The MBean server in which the m-let will be registered.name
- The object name of the m-let.Exception
- This exception should be caught by the MBean server and re-thrown
as an MBeanRegistrationException.public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException, UnsupportedOperationException
Restore this MLet's contents from the given {@link ObjectInput}. Not all implementations support this method. Those that do not throw {@link UnsupportedOperationException}. A subclass may override this method to support it or to change the format of the read data.
The format of the read data is not specified, but if an implementation supports {@link #readExternal} it must also support {@link #writeExternal} in such a way that what is written by the latter can be read by the former.
in
- The object input stream to read from.IOException
- if a problem occurred while reading.ClassNotFoundException
- if the class for the object
being restored cannot be found.UnsupportedOperationException
- if this
implementation does not support this operation.public synchronized void setLibraryDirectory(String libdir)
libdir
- The directory used by the library loader.public void writeExternal(ObjectOutput out) throws IOException, UnsupportedOperationException
Save this MLet's contents to the given {@link ObjectOutput}. Not all implementations support this method. Those that do not throw {@link UnsupportedOperationException}. A subclass may override this method to support it or to change the format of the written data.
The format of the written data is not specified, but if an implementation supports {@link #writeExternal} it must also support {@link #readExternal} in such a way that what is written by the former can be read by the latter.
out
- The object output stream to write to.IOException
- If a problem occurred while writing.UnsupportedOperationException
- If this
implementation does not support this operation.
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