# Class RMIClassLoaderSpi

java.lang.Object
java.rmi.server.RMIClassLoaderSpi

public abstract class RMIClassLoaderSpi extends Object
`RMIClassLoaderSpi` is the service provider interface for `RMIClassLoader`. In particular, an `RMIClassLoaderSpi` instance provides an implementation of the following static methods of `RMIClassLoader`:

- `RMIClassLoader.loadClass(URL,String)`
- `RMIClassLoader.loadClass(String,String)`
- `RMIClassLoader.loadClass(String,String,ClassLoader)`
- `RMIClassLoader.loadProxyClass(String,String[],ClassLoader)`
- `RMIClassLoader.getClassLoader(String)`
- `RMIClassLoader.getClassAnnotation(Class)`

When one of those methods is invoked, its behavior is to delegate to a corresponding method on an instance of this class. The details of how each method delegates to the provider instance is described in the documentation for each particular method. See the documentation for `RMIClassLoader` for a description of how a provider instance is chosen.

Since:
  1.4
See Also:
  - `RMIClassLoader`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `RMIClassLoaderSpi()`
  Constructor for subclasses to call.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `abstract String`
  `getClassAnnotation(Class<?> cl)`
  Provides the implementation for `RMIClassLoader.getClassAnnotation(Class)`.
  `abstract ClassLoader`
  `getClassLoader(String codebase)`
  Provides the implementation for `RMIClassLoader.getClassLoader(String)`.
  `abstract Class<?>`
  `loadClass(String codebase, String name, ClassLoader defaultLoader)`
  Provides the implementation for `RMIClassLoader.loadClass(URL,String)`, `RMIClassLoader.loadClass(String,String)`, and `RMIClassLoader.loadClass(String,String,ClassLoader)`.
  `abstract Class<?>`
  `loadProxyClass(String codebase, String[] interfaces, ClassLoader defaultLoader)`
  Provides the implementation for `RMIClassLoader.loadProxyClass(String,String[],ClassLoader)`.

  ### Methods declared in class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Constructor Details

  - ### RMIClassLoaderSpi

    public RMIClassLoaderSpi()
    Constructor for subclasses to call.

- ## Method Details

  - ### loadClass

    public abstract Class<?> loadClass(String codebase, String name, ClassLoader defaultLoader) throws MalformedURLException, ClassNotFoundException
    Provides the implementation for `RMIClassLoader.loadClass(URL,String)`, `RMIClassLoader.loadClass(String,String)`, and `RMIClassLoader.loadClass(String,String,ClassLoader)`. Loads a class from a codebase URL path, optionally using the supplied loader. 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.

    An implementation of this method must either return a class with the given name or throw an exception.

    Parameters:
      `codebase` - the list of URLs (separated by spaces) to load the class from, or `null`
      `name` - the name of the class to load
      `defaultLoader` - additional contextual class loader to use, or `null`
    Returns:
      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
      `ClassNotFoundException` - if a definition for the class could not be found at the specified location

  - ### loadProxyClass

    public abstract Class<?> loadProxyClass(String codebase, String[] interfaces, ClassLoader defaultLoader) throws MalformedURLException, ClassNotFoundException
    Provides the implementation for `RMIClassLoader.loadProxyClass(String,String[],ClassLoader)`. Loads a dynamic proxy class (see `Proxy` that implements a set of interfaces with the given names from a codebase URL path, optionally using the supplied loader.

    An implementation of this method must either return a proxy class that implements the named interfaces or throw an exception.

    Parameters:
      `codebase` - the list of URLs (space-separated) to load classes from, or `null`
      `interfaces` - the names of the interfaces for the proxy class to implement
      `defaultLoader` - additional contextual class loader to use, or `null`
    Returns:
      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
      `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 `Proxy.getProxyClass(ClassLoader,Class[])` would throw an `IllegalArgumentException` for the given interface list)

  - ### getClassLoader

    public abstract ClassLoader getClassLoader(String codebase) throws MalformedURLException
    Provides the implementation for `RMIClassLoader.getClassLoader(String)`. Returns a class loader that loads classes from the given codebase URL path.
    Parameters:
      `codebase` - the list of URLs (space-separated) from which the returned class loader will load classes from, or `null`
    Returns:
      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

  - ### getClassAnnotation

    public abstract String getClassAnnotation(Class<?> cl)
    Provides the implementation for `RMIClassLoader.getClassAnnotation(Class)`. 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.
    Parameters:
      `cl` - the class to obtain the annotation for
    Returns:
      a string to be used to annotate the given class when it gets marshalled, or `null`
    Throws:
      `NullPointerException` - if `cl` is `null`