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

Modifier and Type	Method and Description
static Analyzer	analyzerInstanceFromClass(Class<?> classToInstantiate, Version luceneMatchVersion)
static <T> Class<? extends T>	classForName(Class<T> targetSuperType, String classNameToLoad, String componentDescription, ServiceManager serviceManager)
static Class	classForName(String classNameToLoad, ServiceManager serviceManager) Perform resolution of a class name.
static Class<?>	classForName(String classNameToLoad, String componentDescription, ServiceManager serviceManager)
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, String componentDescription, ServiceManager serviceManager) 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

instanceFromName

public static <T> T instanceFromName(Class<T> targetSuperType,
                                     String classNameToLoad,
                                     String componentDescription,
                                     ServiceManager serviceManager)

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

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

serviceManager - Service manager allowing access to the class loading service

Returns:

a new instance of the type given by 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 Analyzer analyzerInstanceFromClass(Class<?> classToInstantiate,
                                                 Version luceneMatchVersion)

classForName

public static Class<?> classForName(String classNameToLoad,
                                    String componentDescription,
                                    ServiceManager serviceManager)

classForName

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

classForName

public static Class classForName(String classNameToLoad,
                                 ServiceManager serviceManager)

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:

classNameToLoad - The class name

serviceManager - The service manager from which to retrieve the class loader service

Returns:

The class reference.

Throws:

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