Closeable
, Externalizable
, Serializable
, AutoCloseable
, MLetMBean
, MBeanRegistration
PrivateMLet
@Deprecated(since="20", forRemoval=true) public class MLet extends URLClassLoader implements MLetMBean, MBeanRegistration, Externalizable
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 =
mbeanname
MBeanServer.getDefaultDomain()
. VERSION =
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 MBeanServerFactory.getClassLoaderRepository(javax.management.MBeanServer)
to load classes that could not be found in the loaded jar files.
Constructor | Description |
---|---|
MLet() |
Deprecated, for removal: This API element is subject to removal in a future version. Constructs a new MLet using the default delegation parent ClassLoader. |
MLet |
Deprecated, for removal: This API element is subject to removal in a future version. Constructs a new MLet for the specified URLs using the default delegation parent ClassLoader. |
MLet |
Deprecated, for removal: This API element is subject to removal in a future version. Constructs a new MLet for the specified URLs using the default delegation parent ClassLoader. |
MLet |
Deprecated, for removal: This API element is subject to removal in a future version. Constructs a new MLet for the given URLs. |
MLet |
Deprecated, for removal: This API element is subject to removal in a future version. Constructs a new MLet for the given URLs. |
MLet |
Deprecated, for removal: This API element is subject to removal in a future version. Constructs a new MLet for the specified URLs, parent class loader, and URLStreamHandlerFactory. |
MLet |
Deprecated, for removal: This API element is subject to removal in a future version. Constructs a new MLet for the specified URLs, parent class loader, and URLStreamHandlerFactory. |
Modifier and Type | Method | Description |
---|---|---|
void |
addURL |
Deprecated, for removal: This API element is subject to removal in a future version. Appends the specified URL to the list of URLs to search for classes and resources. |
void |
addURL |
Deprecated, for removal: This API element is subject to removal in a future version. Appends the specified URL to the list of URLs to search for classes and resources. |
protected URL |
check |
Deprecated, for removal: This API element is subject to removal in a future version. This method is to be overridden when extending this service to support caching and versioning. |
protected Class |
findClass |
Deprecated, for removal: This API element is subject to removal in a future version. This is the main method for class loaders that is being redefined. |
protected String |
findLibrary |
Deprecated, for removal: This API element is subject to removal in a future version. Returns the absolute path name of a native library. |
String |
getLibraryDirectory() |
Deprecated, for removal: This API element is subject to removal in a future version. Gets the current directory used by the library loader for storing native libraries before they are loaded into memory. |
Set |
getMBeansFromURL |
Deprecated, for removal: This API element is subject to removal in a future version. Loads a text file containing MLET tags that define the MBeans to be added to the MBean server. |
Set |
getMBeansFromURL |
Deprecated, for removal: This API element is subject to removal in a future version. Loads a text file containing MLET tags that define the MBeans to be added to the MBean server. |
URL[] |
getURLs() |
Deprecated, for removal: This API element is subject to removal in a future version. Returns the search path of URLs for loading classes and resources. |
Class |
loadClass |
Deprecated, for removal: This API element is subject to removal in a future version. Load a class, using the given ClassLoaderRepository if the class is not found in this MLet's URLs. |
void |
postDeregister() |
Deprecated, for removal: This API element is subject to removal in a future version. Allows the m-let to perform any operations needed after having been unregistered in the MBean server. |
void |
postRegister |
Deprecated, for removal: This API element is subject to removal in a future version. Allows the m-let to perform any operations needed after having been registered in the MBean server or after the registration has failed. |
void |
preDeregister() |
Deprecated, for removal: This API element is subject to removal in a future version. Allows the m-let to perform any operations it needs before being unregistered by the MBean server. |
ObjectName |
preRegister |
Deprecated, for removal: This API element is subject to removal in a future version. Allows the m-let to perform any operations it needs before being registered in the MBean server. |
void |
readExternal |
Deprecated, for removal: This API element is subject to removal in a future version. Restore this MLet's contents from the given ObjectInput . |
void |
setLibraryDirectory |
Deprecated, for removal: This API element is subject to removal in a future version. Sets the directory used by the library loader for storing native libraries before they are loaded into memory. |
void |
writeExternal |
Deprecated, for removal: This API element is subject to removal in a future version. Save this MLet's contents to the given ObjectOutput . |
close, definePackage, findResource, findResources, getPermissions, getResourceAsStream, newInstance, newInstance
defineClass, defineClass
clearAssertionStatus, defineClass, defineClass, defineClass, defineClass, definePackage, findClass, findLoadedClass, findResource, findSystemClass, getClassLoadingLock, getDefinedPackage, getDefinedPackages, getName, getPackage, getPackages, getParent, getPlatformClassLoader, getResource, getResources, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, getUnnamedModule, isRegisteredAsParallelCapable, loadClass, loadClass, registerAsParallelCapable, resolveClass, resources, setClassAssertionStatus, setDefaultAssertionStatus, setPackageAssertionStatus, setSigners
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
getResource, getResourceAsStream, getResources
public MLet()
public MLet(URL[] urls)
urls
- The URLs from which to load classes and resources.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, 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, 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 ClassLoaderRepository
.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 ClassLoaderRepository
.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 ClassLoaderRepository
.public void addURL(URL url)
addURL
in interface MLetMBean
addURL
in class URLClassLoader
url
- the URL to be added to the search path of URLspublic void addURL(String url) throws ServiceNotFoundException
addURL
in interface MLetMBean
url
- the URL to add.ServiceNotFoundException
- The specified URL is malformed.public URL[] getURLs()
getURLs
in interface MLetMBean
getURLs
in class URLClassLoader
public Set<Object> getMBeansFromURL(URL url) throws ServiceNotFoundException
getMBeansFromURL
in interface MLetMBean
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.IllegalStateException
- MLet MBean is not registered with an MBeanServer.public Set<Object> getMBeansFromURL(String url) throws ServiceNotFoundException
getMBeansFromURL
in interface MLetMBean
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.IllegalStateException
- MLet MBean is not registered with an MBeanServer.public String getLibraryDirectory()
getLibraryDirectory
in interface MLetMBean
UnsupportedOperationException
- if this implementation does not support storing native libraries in this way.public void setLibraryDirectory(String libdir)
setLibraryDirectory
in interface MLetMBean
libdir
- The directory used by the library loader.UnsupportedOperationException
- if this implementation does not support storing native libraries in this way.public ObjectName preRegister(MBeanServer server, ObjectName name) throws Exception
preRegister
in interface MBeanRegistration
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 postRegister(Boolean registrationDone)
postRegister
in interface MBeanRegistration
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
preDeregister
in interface MBeanRegistration
Exception
- This exception should be caught by the MBean server and re-thrown as an MBeanRegistrationException.public void postDeregister()
postDeregister
in interface MBeanRegistration
public void writeExternal(ObjectOutput out) throws IOException, UnsupportedOperationException
Save this MLet's contents to the given ObjectOutput
. Not all implementations support this method. Those that do not throw 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 writeExternal(java.io.ObjectOutput)
it must also support readExternal(java.io.ObjectInput)
in such a way that what is written by the former can be read by the latter.
writeExternal
in interface Externalizable
out
- The object output stream to write to.IOException
- If a problem occurred while writing.UnsupportedOperationException
- If this implementation does not support this operation.public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException, UnsupportedOperationException
Restore this MLet's contents from the given ObjectInput
. Not all implementations support this method. Those that do not throw 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 readExternal(java.io.ObjectInput)
it must also support writeExternal(java.io.ObjectOutput)
in such a way that what is written by the latter can be read by the former.
readExternal
in interface Externalizable
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 Class<?> loadClass(String name, ClassLoaderRepository clr) throws ClassNotFoundException
Load a class, using the given ClassLoaderRepository
if the class is not found in this MLet's URLs. The given ClassLoaderRepository can be null, in which case a 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.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 nativelibname
be the result of System.mapLibraryName
(libname)
. Then the following names are searched in the JAR files, in order:
nativelibname
<os.name>/<os.arch>/<os.version>/lib/
nativelibname
where <X>
means System.getProperty(X)
with any spaces in the result removed, and /
stands for the file separator character (File.separator
).
If this method returns 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.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 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 getMBeansFromURL
.
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
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https://docs.oracle.com/en/java/javase/21/docs/api/java.management/javax/management/loading/MLet.html