File	Doc	Category	Size	Date	Package
RMIClassLoader.java	API Doc	Java SE 5 API	28286	Fri Aug 26 14:57:12 BST 2005	java.rmi.server

RMIClassLoader

• java.lang.Object

Fields Summary
private static final RMIClassLoaderSpi	defaultProvider "default" provider instance
private static final RMIClassLoaderSpi	provider provider instance

Constructors Summary
private RMIClassLoader() /* * Disallow anyone from creating one of these. */

Methods Summary
public static java.lang.String	getClassAnnotation(java.lang.Class cl) Returns the annotation string (representing a location for the class definition) that RMI will use to annotate the class descriptor when marshalling objects of the given class. This method delegates to the {@link RMIClassLoaderSpi#getClassAnnotation(Class)} method of the provider instance, passing cl as the argument. param cl the class to obtain the annotation for return a string to be used to annotate the given class when it gets marshalled, or null throws NullPointerException if cl is null since 1.2 return provider.getClassAnnotation(cl);
public static java.lang.ClassLoader	getClassLoader(java.lang.String codebase) Returns a class loader that loads classes from the given codebase URL path. The class loader returned is the class loader that the {@link #loadClass(String,String)} method would use to load classes for the same codebase argument. This method delegates to the {@link RMIClassLoaderSpi#getClassLoader(String)} method of the provider instance, passing codebase as the argument. If there is a security manger, its checkPermission method will be invoked with a RuntimePermission("getClassLoader") permission; this could result in a SecurityException. The provider implementation of this method may also perform further security checks to verify that the calling context has permission to connect to all of the URLs in the codebase URL path. param codebase the list of URLs (space-separated) from which the returned class loader will load classes from, or null return a class loader that loads classes from the given codebase URL path throws MalformedURLException if codebase is non-null and contains an invalid URL, or if codebase is null and a provider-specific URL used to identify the class loader is invalid throws SecurityException if there is a security manager and the invocation of its checkPermission method fails, or if the caller does not have permission to connect to all of the URLs in the codebase URL path since 1.3 return provider.getClassLoader(codebase);
public static java.rmi.server.RMIClassLoaderSpi	getDefaultProviderInstance() Returns the canonical instance of the default provider for the service provider interface {@link RMIClassLoaderSpi}. If the system property java.rmi.server.RMIClassLoaderSpi is not defined, then the RMIClassLoader static methods {@link #loadClass(URL,String)} {@link #loadClass(String,String)} {@link #loadClass(String,String,ClassLoader)} {@link #loadProxyClass(String,String[],ClassLoader)} {@link #getClassLoader(String)} {@link #getClassAnnotation(Class)} will use the canonical instance of the default provider as the service provider instance. If there is a security manager, its checkPermission method will be invoked with a RuntimePermission("setFactory") permission; this could result in a SecurityException. The default service provider instance implements {@link RMIClassLoaderSpi} as follows: The {@link RMIClassLoaderSpi#getClassAnnotation(Class) getClassAnnotation} method returns a String representing the codebase URL path that a remote party should use to download the definition for the specified class. The format of the returned string is a path of URLs separated by spaces. The codebase string returned depends on the defining class loader of the specified class: If the class loader is the system class loader (see {@link ClassLoader#getSystemClassLoader}), a parent of the system class loader such as the loader used for installed extensions, or the bootstrap class loader (which may be represented by null), then the value of the java.rmi.server.codebase property (or possibly an earlier cached value) is returned, or null is returned if that property is not set. Otherwise, if the class loader is an instance of URLClassLoader, then the returned string is a space-separated list of the external forms of the URLs returned by invoking the getURLs methods of the loader. If the URLClassLoader was created by this provider to service an invocation of its loadClass or loadProxyClass methods, then no permissions are required to get the associated codebase string. If it is an arbitrary other URLClassLoader instance, then if there is a security manager, its checkPermission method will be invoked once for each URL returned by the getURLs method, with the permission returned by invoking openConnection().getPermission() on each URL; if any of those invocations throws a SecurityException or an IOException, then the value of the java.rmi.server.codebase property (or possibly an earlier cached value) is returned, or null is returned if that property is not set. Finally, if the class loader is not an instance of URLClassLoader, then the value of the java.rmi.server.codebase property (or possibly an earlier cached value) is returned, or null is returned if that property is not set. For the implementations of the methods described below, which all take a String parameter named codebase that is a space-separated list of URLs, each invocation has an associated codebase loader that is identified using the codebase argument in conjunction with the current thread's context class loader (see {@link Thread#getContextClassLoader()}). When there is a security manager, this provider maintains an internal table of class loader instances (which are at least instances of {@link java.net.URLClassLoader}) keyed by the pair of their parent class loader and their codebase URL path (an ordered list of URLs). If the codebase argument is null, the codebase URL path is the value of the system property java.rmi.server.codebase or possibly an earlier cached value. For a given codebase URL path passed as the codebase argument to an invocation of one of the below methods in a given context, the codebase loader is the loader in the table with the specified codebase URL path and the current thread's context class loader as its parent. If no such loader exists, then one is created and added to the table. The table does not maintain strong references to its contained loaders, in order to allow them and their defined classes to be garbage collected when not otherwise reachable. In order to prevent arbitrary untrusted code from being implicitly loaded into a virtual machine with no security manager, if there is no security manager set, the codebase loader is just the current thread's context class loader (the supplied codebase URL path is ignored, so remote class loading is disabled). The {@link RMIClassLoaderSpi#getClassLoader(String) getClassLoader} method returns the codebase loader for the specified codebase URL path. If there is a security manager, then if the calling context does not have permission to connect to all of the URLs in the codebase URL path, a SecurityException will be thrown. The {@link RMIClassLoaderSpi#loadClass(String,String,ClassLoader) loadClass} method attempts to load the class with the specified name as follows: If the defaultLoader argument is non-null, it first attempts to load the class with the specified name using the defaultLoader, such as by evaluating Class.forName(name, false, defaultLoader) If the class is successfully loaded from the defaultLoader, that class is returned. If an exception other than ClassNotFoundException is thrown, that exception is thrown to the caller. Next, the loadClass method attempts to load the class with the specified name using the codebase loader for the specified codebase URL path. If there is a security manager, then the calling context must have permission to connect to all of the URLs in the codebase URL path; otherwise, the current thread's context class loader will be used instead of the codebase loader. The {@link RMIClassLoaderSpi#loadProxyClass(String,String[],ClassLoader) loadProxyClass} method attempts to return a dynamic proxy class with the named interface as follows: If the defaultLoader argument is non-null and all of the named interfaces can be resolved through that loader, then, if all of the resolved interfaces are public, then it first attempts to obtain a dynamic proxy class (using {@link java.lang.reflect.Proxy#getProxyClass(ClassLoader,Class[]) Proxy.getProxyClass}) for the resolved interfaces defined in the codebase loader; if that attempt throws an IllegalArgumentException, it then attempts to obtain a dynamic proxy class for the resolved interfaces defined in the defaultLoader. If both attempts throw IllegalArgumentException, then this method throws a ClassNotFoundException. If any other exception is thrown, that exception is thrown to the caller. if all of the non-public resolved interfaces are defined in the same class loader, then it attempts to obtain a dynamic proxy class for the resolved interfaces defined in that loader. otherwise, a LinkageError is thrown (because a class that implements all of the specified interfaces cannot be defined in any loader). Otherwise, if all of the named interfaces can be resolved through the codebase loader, then, if all of the resolved interfaces are public, then it attempts to obtain a dynamic proxy class for the resolved interfaces in the codebase loader. If the attempt throws an IllegalArgumentException, then this method throws a ClassNotFoundException. if all of the non-public resolved interfaces are defined in the same class loader, then it attempts to obtain a dynamic proxy class for the resolved interfaces defined in that loader. otherwise, a LinkageError is thrown (because a class that implements all of the specified interfaces cannot be defined in any loader). Otherwise, a ClassNotFoundException is thrown for one of the named interfaces that could not be resolved. return the canonical instance of the default service provider throws SecurityException if there is a security manager and the invocation of its checkPermission method fails since 1.4 SecurityManager sm = System.getSecurityManager(); if (sm != null) { sm.checkPermission(new RuntimePermission("setFactory")); } return defaultProvider;
public static java.lang.Object	getSecurityContext(java.lang.ClassLoader loader) Returns the security context of the given class loader. param loader a class loader from which to get the security context return the security context deprecated no replacement. As of the Java 2 platform v1.2, RMI no longer uses this method to obtain a class loader's security context. see java.lang.SecurityManager#getSecurityContext() return sun.rmi.server.LoaderHandler.getSecurityContext(loader);
private static java.rmi.server.RMIClassLoaderSpi	initializeProvider() Chooses provider instance, following above documentation. This method assumes that it has been invoked in a privileged block. /* * First check for the system property being set: */ String providerClassName = System.getProperty("java.rmi.server.RMIClassLoaderSpi"); if (providerClassName != null) { if (providerClassName.equals("default")) { return defaultProvider; } try { Class providerClass = Class.forName(providerClassName, false, ClassLoader.getSystemClassLoader()); return (RMIClassLoaderSpi) providerClass.newInstance(); } catch (ClassNotFoundException e) { throw new NoClassDefFoundError(e.getMessage()); } catch (IllegalAccessException e) { throw new IllegalAccessError(e.getMessage()); } catch (InstantiationException e) { throw new InstantiationError(e.getMessage()); } catch (ClassCastException e) { Error error = new LinkageError( "provider class not assignable to RMIClassLoaderSpi"); error.initCause(e); throw error; } } /* * Next look for a provider configuration file intalled: */ Iterator iter = Service.providers(RMIClassLoaderSpi.class, ClassLoader.getSystemClassLoader()); if (iter.hasNext()) { try { return (RMIClassLoaderSpi) iter.next(); } catch (ClassCastException e) { Error error = new LinkageError( "provider class not assignable to RMIClassLoaderSpi"); error.initCause(e); throw error; } } /* * Finally, return the canonical instance of the default provider. */ return defaultProvider;
public static java.lang.Class	loadClass(java.lang.String name) Loads the class with the specified name. This method delegates to {@link #loadClass(String,String)}, passing null as the first argument and name as the second argument. param name the name of the class to load return the Class object representing the loaded class throws MalformedURLException if a provider-specific URL used to load classes is invalid throws ClassNotFoundException if a definition for the class could not be found at the codebase location deprecated replaced by loadClass(String,String) method see #loadClass(String,String) return loadClass((String) null, name);
public static java.lang.Class	loadClass(java.net.URL codebase, java.lang.String name) Loads a class from a codebase URL. If codebase is null, then this method will behave the same as {@link #loadClass(String,String)} with a null codebase and the given class name. This method delegates to the {@link RMIClassLoaderSpi#loadClass(String,String,ClassLoader)} method of the provider instance, passing the result of invoking {@link URL#toString} on the given URL (or null if codebase is null) as the first argument, name as the second argument, and null as the third argument. param codebase the URL to load the class from, or null param name the name of the class to load return the Class object representing the loaded class throws MalformedURLException if codebase is null and a provider-specific URL used to load classes is invalid throws ClassNotFoundException if a definition for the class could not be found at the specified URL return provider.loadClass( codebase != null ? codebase.toString() : null, name, null);
public static java.lang.Class	loadClass(java.lang.String codebase, java.lang.String name) Loads a class from a codebase URL path. This method delegates to the {@link RMIClassLoaderSpi#loadClass(String,String,ClassLoader)} method of the provider instance, passing codebase as the first argument, name as the second argument, and null as the third argument. param codebase the list of URLs (separated by spaces) to load the class from, or null param name the name of the class to load return the Class object representing the loaded class throws MalformedURLException if codebase is non-null and contains an invalid URL, or if codebase is null and a provider-specific URL used to load classes is invalid throws ClassNotFoundException if a definition for the class could not be found at the specified location since 1.2 return provider.loadClass(codebase, name, null);
public static java.lang.Class	loadClass(java.lang.String codebase, java.lang.String name, java.lang.ClassLoader defaultLoader) Loads a class from a codebase URL path, optionally using the supplied loader. This method should be used when the caller would like to make available to the provider implementation an additional contextual class loader to consider, such as the loader of a caller on the stack. Typically, a provider implementation will attempt to resolve the named class using the given defaultLoader, if specified, before attempting to resolve the class from the codebase URL path. This method delegates to the {@link RMIClassLoaderSpi#loadClass(String,String,ClassLoader)} method of the provider instance, passing codebase as the first argument, name as the second argument, and defaultLoader as the third argument. param codebase the list of URLs (separated by spaces) to load the class from, or null param name the name of the class to load param defaultLoader additional contextual class loader to use, or null return the Class object representing the loaded class throws MalformedURLException if codebase is non-null and contains an invalid URL, or if codebase is null and a provider-specific URL used to load classes is invalid throws ClassNotFoundException if a definition for the class could not be found at the specified location since 1.4 return provider.loadClass(codebase, name, defaultLoader);
public static java.lang.Class	loadProxyClass(java.lang.String codebase, java.lang.String[] interfaces, java.lang.ClassLoader defaultLoader) Loads a dynamic proxy class (see {@link java.lang.reflect.Proxy}) that implements a set of interfaces with the given names from a codebase URL path. The interfaces will be resolved similar to classes loaded via the {@link #loadClass(String,String)} method using the given codebase. This method delegates to the {@link RMIClassLoaderSpi#loadProxyClass(String,String[],ClassLoader)} method of the provider instance, passing codebase as the first argument, interfaces as the second argument, and defaultLoader as the third argument. param codebase the list of URLs (space-separated) to load classes from, or null param interfaces the names of the interfaces for the proxy class to implement param defaultLoader additional contextual class loader to use, or null return a dynamic proxy class that implements the named interfaces throws MalformedURLException if codebase is non-null and contains an invalid URL, or if codebase is null and a provider-specific URL used to load classes is invalid throws ClassNotFoundException if a definition for one of the named interfaces could not be found at the specified location, or if creation of the dynamic proxy class failed (such as if {@link java.lang.reflect.Proxy#getProxyClass(ClassLoader,Class[])} would throw an IllegalArgumentException for the given interface list) since 1.4 return provider.loadProxyClass(codebase, interfaces, defaultLoader);
private static java.rmi.server.RMIClassLoaderSpi	newDefaultProviderInstance() Creates an instance of the default provider class. return new RMIClassLoaderSpi() { public Class loadClass(String codebase, String name, ClassLoader defaultLoader) throws MalformedURLException, ClassNotFoundException { return sun.rmi.server.LoaderHandler.loadClass( codebase, name, defaultLoader); } public Class loadProxyClass(String codebase, String[] interfaces, ClassLoader defaultLoader) throws MalformedURLException, ClassNotFoundException { return sun.rmi.server.LoaderHandler.loadProxyClass( codebase, interfaces, defaultLoader); } public ClassLoader getClassLoader(String codebase) throws MalformedURLException { return sun.rmi.server.LoaderHandler.getClassLoader(codebase); } public String getClassAnnotation(Class<?> cl) { return sun.rmi.server.LoaderHandler.getClassAnnotation(cl); } };