org.apache.velocity.util

Class ClassUtils

java.lang.Object

org.apache.velocity.util.ClassUtils

public class ClassUtils
extends Object

Simple utility functions for manipulating classes and resources from the classloader.

Since:

1.5

Version:

$Id: ClassUtils.java 1872422 2020-01-07 09:37:17Z cbrisson $

Author:

Will Glass-Husain

Method Summary

Modifier and Type	Method and Description
static Class	getClass(String clazz) Return the specified class.
static VelMethod	getMethod(String methodName, Object[] params, Class[] paramClasses, Object o, InternalContextAdapter context, SimpleNode node, boolean strictRef) Lookup a VelMethod object given the method signature that is specified in the passed in parameters.
static Object	getNewInstance(String clazz) Return a new instance of the given class.
static InputStream	getResourceAsStream(Class claz, String name) Finds a resource with the given name.

Methods inherited from class java.lang.Object

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

Method Detail

getClass

public static Class getClass(String clazz)
                      throws ClassNotFoundException

Return the specified class. Checks the ThreadContext classloader first, then uses the System classloader. Should replace all calls to Class.forName( claz ) (which only calls the System class loader) when the class might be in a different classloader (e.g. in a webapp).

Parameters:

clazz - the name of the class to instantiate

Returns:

the requested Class object

Throws:

ClassNotFoundException

getNewInstance

public static Object getNewInstance(String clazz)
                             throws ClassNotFoundException,
                                    IllegalAccessException,
                                    InstantiationException

Return a new instance of the given class. Checks the ThreadContext classloader first, then uses the System classloader. Should replace all calls to Class.forName( claz ).newInstance() (which only calls the System class loader) when the class might be in a different classloader (e.g. in a webapp).

Parameters:

clazz - the name of the class to instantiate

Returns:

an instance of the specified class

Throws:

ClassNotFoundException

IllegalAccessException

InstantiationException

getResourceAsStream

public static InputStream getResourceAsStream(Class claz,
                                              String name)

Finds a resource with the given name. Checks the Thread Context classloader, then uses the System classloader. Should replace all calls to Class.getResourceAsString when the resource might come from a different classloader. (e.g. a webapp).

Parameters:

claz - Class to use when getting the System classloader (used if no Thread Context classloader available or fails to get resource).

name - name of the resource

Returns:

InputStream for the resource.

getMethod

public static VelMethod getMethod(String methodName,
                                  Object[] params,
                                  Class[] paramClasses,
                                  Object o,
                                  InternalContextAdapter context,
                                  SimpleNode node,
                                  boolean strictRef)

Lookup a VelMethod object given the method signature that is specified in the passed in parameters. This method first searches the cache, if not found in the cache then uses reflections to inspect Object o, for the given method.

Parameters:

methodName - Name of method

params - Array of objects that are parameters to the method

paramClasses - Array of Classes corresponding to the types in params.

o - Object to introspect for the given method.

context - Context from which the method cache is acquired

node - ASTNode, used for error reporting.

strictRef - If no method is found, throw an exception, never return null in this case

Returns:

VelMethod object if the object is found, null if not matching method is found