KeyTransformationHandler (Infinispan Query 14.0.2.Final API)

java.lang.Object
- org.infinispan.query.backend.KeyTransformationHandler

```
public final class KeyTransformationHandler
extends Object
```
This transforms arbitrary keys to a String which can be used by Lucene as a document identifier, and vice versa.
There are 2 approaches to doing so; one for simple keys: Java primitives (and their object wrappers), byte[], Strings and UUID, and one for custom, user-defined types that could be used as keys.
For simple keys, users don't need to do anything, these keys are automatically transformed by this class.
For user-defined keys, three options are supported. Types annotated with @Transformable, and declaring an appropriate Transformer implementation, types for which a Transformer has been explicitly registered through KeyTransformationHandler.registerTransformer() or through the indexing configuration (IndexingConfigurationBuilder.addKeyTransformer(java.lang.Class<?>, java.lang.Class<?>)).

Since:

4.0

Author:

Manik Surtani, Marko Luksa

See Also:

Transformable, Transformer

Constructor Summary

Constructors
Constructor Description

KeyTransformationHandler(ClassLoader classLoader)
Constructs a KeyTransformationHandler for an indexed Cache.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`String`	`keyToString(Object key)`	Stringify a key so Lucene can use it as document id.
`void`	`registerTransformer(Class<?> keyClass, Class<? extends Transformer> transformerClass)`	Registers a `Transformer` for the supplied key class.
`Object`	`stringToKey(String s)`	Converts a Lucene document id from string form back to the original object.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - KeyTransformationHandler
```
public KeyTransformationHandler(ClassLoader classLoader)
```
    Constructs a KeyTransformationHandler for an indexed Cache.
    
    Parameters:
    
    classLoader - the classloader of the cache that owns this KeyTransformationHandler or null if the thread context classloader is to be used (acceptable for testing only!)
- Method Detail
  - stringToKey
```
public Object stringToKey(String s)
```
    Converts a Lucene document id from string form back to the original object.
    
    Parameters:
    
    s - the string form of the key
    
    Returns:
    
    the key object
  - keyToString
```
public String keyToString(Object key)
```
    Stringify a key so Lucene can use it as document id.
    
    Parameters:
    
    key - the key
    
    Returns:
    
    a string form of the key
  - registerTransformer
```
public void registerTransformer(Class<?> keyClass,
                                Class<? extends Transformer> transformerClass)
```
    Registers a Transformer for the supplied key class.
    
    Parameters:
    
    keyClass - the key class for which the supplied transformerClass should be used
    
    transformerClass - the transformer class to use for the supplied key class