org.hibernate.search.util.impl

Class ClassLoaderHelper

java.lang.Object

org.hibernate.search.util.impl.ClassLoaderHelper

public class ClassLoaderHelper
extends Object

Utility class to load instances of other classes by using a fully qualified name, or from a class type. Uses reflection and throws SearchException(s) with proper descriptions of the error, like the target class is missing a proper constructor, is an interface, is not found...

Author:

Sanne Grinovero, Hardy Ferentschik, Ales Justin

Method Summary

Methods

Modifier and Type	Method and Description
static org.apache.lucene.analysis.Analyzer	analyzerInstanceFromClass(Class<?> classToInstantiate, org.apache.lucene.util.Version luceneMatchVersion)
static <T> Class<? extends T>	classForName(Class<T> targetSuperType, String classNameToLoad, ClassLoader classLoader, String componentDescription)
static Class	classForName(String name, ClassLoader classLoader) Perform resolution of a class name.
static Class<?>	classForName(String classNameToLoad, ClassLoader classLoader, String componentDescription)
static Enumeration<URL>	getResources(String resourceName, Class<?> caller) Load all resources matching a specific name
static <T> T	instanceFromClass(Class<T> targetSuperType, Class<?> classToLoad, String componentDescription) Creates an instance of target class
static <T> T	instanceFromClass(Class<T> targetSuperType, Class<?> classToLoad, String componentDescription, Map<String,String> constructorParameter) Creates an instance of target class having a Map of strings as constructor parameter.
static <T> T	instanceFromName(Class<T> targetSuperType, String classNameToLoad, Class<?> caller, String componentDescription) Deprecated. Use instanceFromName(Class, String, ClassLoader, String) instead
static <T> T	instanceFromName(Class<T> targetSuperType, String classNameToLoad, ClassLoader fallbackClassLoader, String componentDescription) Creates an instance of a target class specified by the fully qualified class name using a ClassLoader as fallback when the class cannot be found in the context one.

Methods inherited from class java.lang.Object

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

Method Detail

getResources

public static Enumeration<URL> getResources(String resourceName,
                            Class<?> caller)

Load all resources matching a specific name

Parameters:

resourceName - the resource name

caller - the caller

Returns:

found resource URLs

instanceFromName

@Deprecated
public static <T> T instanceFromName(Class<T> targetSuperType,
                                String classNameToLoad,
                                Class<?> caller,
                                String componentDescription)

Deprecated. Use instanceFromName(Class, String, ClassLoader, String) instead

Creates an instance of a target class designed by fully qualified name

Type Parameters:

T - matches the type of targetSuperType: defines the return type

Parameters:

targetSuperType - the return type of the function, the classNameToLoad will be checked to be assignable to this type.

classNameToLoad - a fully qualified class name, whose type is assignable to targetSuperType

caller - the class of the caller, needed for classloading purposes

componentDescription - a meaningful description of the role the instance will have, used to enrich error messages to describe the context of the error

Returns:

a new instance of classNameToLoad

Throws:

SearchException - wrapping other error types with a proper error message for all kind of problems, like classNotFound, missing proper constructor, wrong type, security errors.

instanceFromName

public static <T> T instanceFromName(Class<T> targetSuperType,
                     String classNameToLoad,
                     ClassLoader fallbackClassLoader,
                     String componentDescription)

Creates an instance of a target class specified by the fully qualified class name using a ClassLoader as fallback when the class cannot be found in the context one.

Type Parameters:

T - matches the type of targetSuperType: defines the return type

Parameters:

targetSuperType - the return type of the function, the classNameToLoad will be checked to be assignable to this type.

classNameToLoad - a fully qualified class name, whose type is assignable to targetSuperType

fallbackClassLoader - the ClassLoader used when the class cannot be found in the context one

componentDescription - a meaningful description of the role the instance will have, used to enrich error messages to describe the context of the error

Returns:

a new instance of classNameToLoad

Throws:

SearchException - wrapping other error types with a proper error message for all kind of problems, like classNotFound, missing proper constructor, wrong type, security errors.

instanceFromClass

public static <T> T instanceFromClass(Class<T> targetSuperType,
                      Class<?> classToLoad,
                      String componentDescription)

Creates an instance of target class

Type Parameters:

T - the type of targetSuperType: defines the return type

Parameters:

targetSuperType - the created instance will be checked to be assignable to this type

classToLoad - the class to be instantiated

componentDescription - a role name/description to contextualize error messages

Returns:

a new instance of classToLoad

Throws:

SearchException - wrapping other error types with a proper error message for all kind of problems, like missing proper constructor, wrong type, security errors.

instanceFromClass

public static <T> T instanceFromClass(Class<T> targetSuperType,
                      Class<?> classToLoad,
                      String componentDescription,
                      Map<String,String> constructorParameter)

Creates an instance of target class having a Map of strings as constructor parameter. Most of the Analyzer SPIs provided by Lucene have such a constructor.

Type Parameters:

T - the type of targetSuperType: defines the return type

Parameters:

targetSuperType - the created instance will be checked to be assignable to this type

classToLoad - the class to be instantiated

componentDescription - a role name/description to contextualize error messages

constructorParameter - a Map to be passed to the constructor. The loaded type must have such a constructor.

Returns:

a new instance of classToLoad

Throws:

SearchException - wrapping other error types with a proper error message for all kind of problems, like missing proper constructor, wrong type, security errors.

analyzerInstanceFromClass

public static org.apache.lucene.analysis.Analyzer analyzerInstanceFromClass(Class<?> classToInstantiate,
                                                            org.apache.lucene.util.Version luceneMatchVersion)

classForName

public static Class<?> classForName(String classNameToLoad,
                    ClassLoader classLoader,
                    String componentDescription)

classForName

public static <T> Class<? extends T> classForName(Class<T> targetSuperType,
                                  String classNameToLoad,
                                  ClassLoader classLoader,
                                  String componentDescription)

classForName

public static Class classForName(String name,
                 ClassLoader classLoader)
                          throws ClassNotFoundException

Perform resolution of a class name.

Here we first check the context classloader, if one, before delegating to Class.forName(String, boolean, ClassLoader) using the caller's classloader

Parameters:

name - The class name

classLoader - The classloader from which this call originated.

Returns:

The class reference.

Throws:

ClassNotFoundException - From Class.forName(String, boolean, ClassLoader).