Package org.jboss.modules
Class ConcurrentClassLoader
- java.lang.Object
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- java.lang.ClassLoader
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- org.jboss.modules.ConcurrentClassLoader
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- Direct Known Subclasses:
ModuleClassLoader
public abstract class ConcurrentClassLoader extends ClassLoader
A classloader which can delegate to multiple other classloaders without risk of deadlock. A concurrent class loader should only ever be delegated to by another concurrent class loader; however a concurrent class loader may delegate to a standard hierarchical class loader. In other words, holding a lock on another class loader while invoking a method on this class loader may cause an unexpected deadlock.- Author:
- David M. Lloyd
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Field Summary
Fields Modifier and Type Field Description protected static Enumeration<URL>
EMPTY_ENUMERATION
An empty enumeration, for subclasses to use if desired.
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Constructor Summary
Constructors Modifier Constructor Description protected
ConcurrentClassLoader()
Construct a new instance, using our class loader as the parent.protected
ConcurrentClassLoader(ConcurrentClassLoader parent)
Construct a new instance with the given parent class loader, which must be a concurrent class loader, ornull
to create a root concurrent class loader.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description protected Class<?>
defineOrLoadClass(String className, byte[] bytes, int off, int len)
Atomically define or load the named class.protected Class<?>
defineOrLoadClass(String className, byte[] bytes, int off, int len, ProtectionDomain protectionDomain)
Atomically define or load the named class.protected Package
definePackage(String name, String specTitle, String specVersion, String specVendor, String implTitle, String implVersion, String implVendor, URL sealBase)
Defines a package by name in this ConcurrentClassLoader.protected Class<?>
findClass(String className)
Implementation ofClassLoader.findClass(String)
.protected Class<?>
findClass(String className, boolean exportsOnly, boolean resolve)
Find a class, possibly delegating to other loader(s).protected Package
findLoadedPackage(String name)
Load a package from this class loader only.protected URL
findResource(String name)
Never used.protected URL
findResource(String name, boolean exportsOnly)
Find the resource with the given name and exported status.protected InputStream
findResourceAsStream(String name, boolean exportsOnly)
Finds the resource with the given name and exported status, returning the resource content as a stream.protected Enumeration<URL>
findResources(String name)
Never used.protected Enumeration<URL>
findResources(String name, boolean exportsOnly)
Finds the resources with the given name and exported status.protected Package
getPackage(String name)
Load a package which is visible to this class loader.protected Package
getPackageByName(String name)
Perform the actual work to load a package which is visible to this class loader.protected Package[]
getPackages()
Get all defined packages which are visible to this class loader.URL
getResource(String name)
Finds the resource with the given name.InputStream
getResourceAsStream(String name)
Returns an input stream for reading the specified resource.Enumeration<URL>
getResources(String name)
Finds all available resources with the given name.Class<?>
loadClass(String className)
Loads the class with the specified binary name.Class<?>
loadClass(String className, boolean resolve)
Loads the class with the specified binary name.Class<?>
loadExportedClass(String className)
Same asloadClass(String)
, except only exported classes will be considered.Class<?>
loadExportedClass(String className, boolean resolve)
Same asloadClass(String,boolean)
, except only exported classes will be considered.-
Methods inherited from class java.lang.ClassLoader
clearAssertionStatus, defineClass, defineClass, defineClass, defineClass, findClass, findLibrary, findLoadedClass, findResource, findSystemClass, getClassLoadingLock, getDefinedPackage, getDefinedPackages, getName, getParent, getPlatformClassLoader, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, getUnnamedModule, isRegisteredAsParallelCapable, registerAsParallelCapable, resolveClass, resources, setClassAssertionStatus, setDefaultAssertionStatus, setPackageAssertionStatus, setSigners
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Field Detail
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EMPTY_ENUMERATION
protected static final Enumeration<URL> EMPTY_ENUMERATION
An empty enumeration, for subclasses to use if desired.
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Constructor Detail
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ConcurrentClassLoader
protected ConcurrentClassLoader(ConcurrentClassLoader parent)
Construct a new instance with the given parent class loader, which must be a concurrent class loader, ornull
to create a root concurrent class loader.- Parameters:
parent
- the parent class loader
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ConcurrentClassLoader
protected ConcurrentClassLoader()
Construct a new instance, using our class loader as the parent.
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Method Detail
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loadClass
public final Class<?> loadClass(String className) throws ClassNotFoundException
Loads the class with the specified binary name. Equivalent to callingloadClass(className, false)
.- Overrides:
loadClass
in classClassLoader
- Parameters:
className
- The binary name of the class- Returns:
- the resulting
Class
instance - Throws:
ClassNotFoundException
- if the class was not found
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loadClass
public final Class<?> loadClass(String className, boolean resolve) throws ClassNotFoundException
Loads the class with the specified binary name.- Overrides:
loadClass
in classClassLoader
- Parameters:
className
- The binary name of the classresolve
-true
if the class should be linked after loading- Returns:
- the resulting
Class
instance - Throws:
ClassNotFoundException
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loadExportedClass
public final Class<?> loadExportedClass(String className) throws ClassNotFoundException
Same asloadClass(String)
, except only exported classes will be considered.- Parameters:
className
- the class name- Returns:
- the class
- Throws:
ClassNotFoundException
- if the class isn't found
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loadExportedClass
public final Class<?> loadExportedClass(String className, boolean resolve) throws ClassNotFoundException
Same asloadClass(String,boolean)
, except only exported classes will be considered.- Parameters:
className
- the class nameresolve
-true
if the class should be linked after loading- Returns:
- the class
- Throws:
ClassNotFoundException
- if the class isn't found
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findClass
protected Class<?> findClass(String className, boolean exportsOnly, boolean resolve) throws ClassNotFoundException
Find a class, possibly delegating to other loader(s). This method should never synchronize across a delegation method call of any sort. The default implementation always throwsClassNotFoundException
.If a class is to be defined by this method, it should be done via one of the atomic
defineOrLoadClass
methods rather thandefineClass()
in order to avoid spurious exceptions.- Parameters:
className
- the class nameexportsOnly
-true
if only exported classes should be consideredresolve
-true
if the class should be linked after loading- Returns:
- the class
- Throws:
ClassNotFoundException
- if the class is not found
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defineOrLoadClass
protected final Class<?> defineOrLoadClass(String className, byte[] bytes, int off, int len)
Atomically define or load the named class. If the class is already defined, the existing class is returned.- Parameters:
className
- the class name to define or loadbytes
- the bytes to use to define the classoff
- the offset into the byte array at which the class bytes beginlen
- the number of bytes in the class- Returns:
- the class
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defineOrLoadClass
protected final Class<?> defineOrLoadClass(String className, byte[] bytes, int off, int len, ProtectionDomain protectionDomain)
Atomically define or load the named class. If the class is already defined, the existing class is returned.- Parameters:
className
- the class name to define or loadbytes
- the bytes to use to define the classoff
- the offset into the byte array at which the class bytes beginlen
- the number of bytes in the classprotectionDomain
- the protection domain for the defined class- Returns:
- the class
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findClass
protected final Class<?> findClass(String className) throws ClassNotFoundException
Implementation ofClassLoader.findClass(String)
.- Overrides:
findClass
in classClassLoader
- Parameters:
className
- the class name- Returns:
- the result of
findClass(className, false, false)
- Throws:
ClassNotFoundException
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getResource
public final URL getResource(String name)
Finds the resource with the given name. The name of a resource is a'/'
-separated path name that identifies the resource. If the resource name starts with"java/"
then the parent class loader is used. Otherwise, this method delegates tofindResource(String, boolean)
.- Overrides:
getResource
in classClassLoader
- Parameters:
name
- the name of the resource- Returns:
- the resource URL, or
null
if no such resource exists or the invoker does not have adequate permission to access it
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getResources
public final Enumeration<URL> getResources(String name) throws IOException
Finds all available resources with the given name.- Overrides:
getResources
in classClassLoader
- Parameters:
name
- the resource name- Returns:
- an enumeration over all the resource URLs; if no resources could be found, the enumeration will be empty
- Throws:
IOException
- if an I/O error occurs- See Also:
getResource(String)
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findResource
protected URL findResource(String name, boolean exportsOnly)
Find the resource with the given name and exported status.- Parameters:
name
- the resource nameexportsOnly
-true
to consider only exported resources orfalse
to consider all resources- Returns:
- the resource URL
- See Also:
getResource(String)
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findResource
protected final URL findResource(String name)
Never used.ClassLoader.getResource(String)
and related methods can cause a loop condition when this method is implemented; usefindResource(String, boolean)
instead.- Overrides:
findResource
in classClassLoader
- Parameters:
name
- ignored- Returns:
null
always
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findResources
protected Enumeration<URL> findResources(String name, boolean exportsOnly) throws IOException
Finds the resources with the given name and exported status.- Parameters:
name
- the resource nameexportsOnly
-true
to consider only exported resources orfalse
to consider all resources- Returns:
- the resource enumeration
- Throws:
IOException
- if an I/O error occurs- See Also:
getResources(String)
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findResources
protected final Enumeration<URL> findResources(String name)
Never used.ClassLoader.getResources(String)
and related methods can cause a loop condition when this method is implemented; usefindResources(String, boolean)
instead. By default, returns an empty enumeration.- Overrides:
findResources
in classClassLoader
- Parameters:
name
- ignored- Returns:
- an empty enumeration
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findResourceAsStream
protected InputStream findResourceAsStream(String name, boolean exportsOnly)
Finds the resource with the given name and exported status, returning the resource content as a stream.- Parameters:
name
- the resource nameexportsOnly
-true
to consider only exported resources orfalse
to consider all resources- Returns:
- the resource stream, or
null
if the resource is not found
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getResourceAsStream
public final InputStream getResourceAsStream(String name)
Returns an input stream for reading the specified resource. If the resource starts with"java/"
, then this method delegates to the parent class loader. Otherwise, this method delegates tofindResourceAsStream(String, boolean)
.- Overrides:
getResourceAsStream
in classClassLoader
- Parameters:
name
- the resource name- Returns:
- the resource stream, or
null
if the resource is not found
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getPackage
protected final Package getPackage(String name)
Load a package which is visible to this class loader.- Overrides:
getPackage
in classClassLoader
- Parameters:
name
- the package name- Returns:
- the package, or
null
if no such package is visible to this class loader
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getPackageByName
protected Package getPackageByName(String name)
Perform the actual work to load a package which is visible to this class loader. By default, uses a simple parent-first delegation strategy.- Parameters:
name
- the package name- Returns:
- the package, or
null
if no such package is visible to this class loader
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getPackages
protected Package[] getPackages()
Get all defined packages which are visible to this class loader.- Overrides:
getPackages
in classClassLoader
- Returns:
- the packages
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findLoadedPackage
protected final Package findLoadedPackage(String name)
Load a package from this class loader only.- Parameters:
name
- the package name- Returns:
- the package or
null
if no such package is defined by this class loader
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definePackage
protected Package definePackage(String name, String specTitle, String specVersion, String specVendor, String implTitle, String implVersion, String implVendor, URL sealBase) throws IllegalArgumentException
Defines a package by name in this ConcurrentClassLoader. If the package was already defined, the existing package is returned instead.- Overrides:
definePackage
in classClassLoader
- Parameters:
name
- the package namespecTitle
- the specification titlespecVersion
- the specification versionspecVendor
- the specification vendorimplTitle
- the implementation titleimplVersion
- the implementation versionimplVendor
- the implementation vendorsealBase
- if notnull
, then this package is sealed with respect to the given code source URL- Returns:
- the newly defined package, or the existing one if one was already defined
- Throws:
IllegalArgumentException
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