org.xbib.elasticsearch.plugin.jdbc.classloader.uri

Class URIClassLoader

java.lang.Object

java.lang.ClassLoader

java.security.SecureClassLoader

java.net.URLClassLoader

org.xbib.elasticsearch.plugin.jdbc.classloader.uri.URIClassLoader

All Implemented Interfaces:

Closeable, AutoCloseable

public final class URIClassLoader
extends URLClassLoader

Equivalent of java.net.URLClassloader but without bugs related to ill-formed URLs and with customizable JAR caching policy. The standard URLClassLoader accepts URLs containing spaces and other characters which are forbidden in the URI syntax, according to the RFC 2396. As a workaround to this problem, Java escapes and un-escapes URLs in various arbitrary places; however, this is inconsistent and leads to numerous problems with URLs referring to local files with spaces in the path. SUN acknowledges the problem, but refuses to modify the behavior for compatibility reasons; see Java Bug Parade 4273532, 4466485.

Additionally, the JAR caching policy used by URLClassLoader is system-wide and inflexible: once downloaded JAR files are never re-downloaded, even if one creates a fresh instance of the class loader that happens to have the same URL in its search path. In fact, that policy is a security vulnerability: it is possible to crash any URL class loader, thus affecting potentially separate part of the system, by creating URL connection to one of the URLs of that class loader search path and closing the associated JAR file. See Java Bug Parade 4405789, 4388666, 4639900.

This class avoids these problems by 1) using URIs instead of URLs for the search path (thus enforcing strict syntax conformance and defining precise escaping semantics), and 2) using custom URLStreamHandler which ensures per-classloader JAR caching policy.

Constructor Summary

Constructors

Constructor and Description
URIClassLoader() Creates URIClassLoader
URIClassLoader(ClassLoader parent) Creates URIClassLoader with the specified parent class loader.

Method Summary

Methods

Modifier and Type	Method and Description
URIClassLoader	addURI(URI uri) Add specified URI at the end of the search path.
protected void	addURL(URL url) Deprecated. use addURI
protected Class	findClass(String name) Finds and loads the class with the specified name.
protected String	findLibrary(String libname) Returns the absolute path name of a native library.
URL	findResource(String name) Finds the resource with the specified name.
Enumeration<URL>	findResources(String name) Returns an Enumeration of URLs representing all of the resources having the specified name.
URI[]	getURIs()
String	toString()

Methods inherited from class java.net.URLClassLoader

close, definePackage, getPermissions, getResourceAsStream, getURLs, newInstance, newInstance

Methods inherited from class java.security.SecureClassLoader

defineClass, defineClass

Methods inherited from class java.lang.ClassLoader

clearAssertionStatus, defineClass, defineClass, defineClass, defineClass, definePackage, findLoadedClass, findSystemClass, getClassLoadingLock, getPackage, getPackages, getParent, getResource, getResources, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, loadClass, loadClass, registerAsParallelCapable, resolveClass, setClassAssertionStatus, setDefaultAssertionStatus, setPackageAssertionStatus, setSigners

Methods inherited from class java.lang.Object

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

Constructor Detail

URIClassLoader

public URIClassLoader()

Creates URIClassLoader

URIClassLoader

public URIClassLoader(ClassLoader parent)

Creates URIClassLoader with the specified parent class loader.

Parameters:

parent - the parent class loader.

Method Detail

addURI

public URIClassLoader addURI(URI uri)

Add specified URI at the end of the search path.

Parameters:

uri - the URI to add

getURIs

public URI[] getURIs()

addURL

@Deprecated
protected void addURL(URL url)

Deprecated. use addURI

Add specified URL at the end of the search path.

Overrides:

addURL in class URLClassLoader

Parameters:

url - the URL to add

findClass

protected Class findClass(String name)
                   throws ClassNotFoundException

Finds and loads the class with the specified name.

Overrides:

findClass in class URLClassLoader

Parameters:

name - the name of the class

Returns:

the resulting class

Throws:

ClassNotFoundException - if the class could not be found

findResource

public URL findResource(String name)

Finds the resource with the specified name.

Overrides:

findResource in class URLClassLoader

Parameters:

name - the name of the resource

Returns:

a URL for the resource, or null if the resource could not be found.

findResources

public Enumeration<URL> findResources(String name)
                               throws IOException

Returns an Enumeration of URLs representing all of the resources having the specified name.

Overrides:

findResources in class URLClassLoader

Parameters:

name - the resource name

Returns:

an Enumeration of URLs

Throws:

IOException - if an I/O exception occurs

findLibrary

protected String findLibrary(String libname)

Returns the absolute path name of a native library. The VM invokes this method to locate the native libraries that belong to classes loaded with this class loader. If this method returns null, the VM searches the library along the path specified as the java.library.path property. This method invoke getLibraryHandle(java.lang.String) method to find handle of this library. If the handle is found and its URL protocol is "file", the system-dependent absolute library file path is returned. Otherwise this method returns null.

Subclasses can override this method to provide specific approaches in library searching.

Overrides:

findLibrary in class ClassLoader

Parameters:

libname - the library name

Returns:

the absolute path of the native library

See Also:

System.loadLibrary(String), System.mapLibraryName(String)

toString

public String toString()

Overrides:

toString in class Object