KeySelector (Java SE 10 & JDK 10 )

java.lang.Object
- javax.xml.crypto.KeySelector

```
public abstract class KeySelector
extends Object
```
A selector that finds and returns a key using the data contained in a KeyInfo object. An example of an implementation of this class is one that searches a KeyStore for trusted keys that match information contained in a KeyInfo.
Whether or not the returned key is trusted and the mechanisms used to determine that is implementation-specific.

Since:

1.6

Nested Class Summary

Nested Classes
Modifier and Type Class Description

static class KeySelector.Purpose
The purpose of the key that is to be selected.

Nested Classes
Modifier and Type	Class	Description
`static class`	`KeySelector.Purpose`	The purpose of the key that is to be selected.

Constructor Summary

Constructors
Modifier Constructor Description

protected KeySelector()
Default no-args constructor; intended for invocation by subclasses only.

Constructors
Modifier	Constructor	Description
`protected`	`KeySelector()`	Default no-args constructor; intended for invocation by subclasses only.

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`abstract KeySelectorResult`	`select(KeyInfo keyInfo, KeySelector.Purpose purpose, AlgorithmMethod method, XMLCryptoContext context)`	Attempts to find a key that satisfies the specified constraints.
`static KeySelector`	`singletonKeySelector(Key key)`	Returns a `KeySelector` that always selects the specified key, regardless of the `KeyInfo` passed to it.

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

- Constructor Detail
  - KeySelector
```
protected KeySelector()
```
    Default no-args constructor; intended for invocation by subclasses only.
- Method Detail
  - select
```
public abstract KeySelectorResult select(KeyInfo keyInfo,
                                         KeySelector.Purpose purpose,
                                         AlgorithmMethod method,
                                         XMLCryptoContext context)
                                  throws KeySelectorException
```
    Attempts to find a key that satisfies the specified constraints.
    
    Parameters:
    
    keyInfo - a KeyInfo (may be null)
    
    purpose - the key's purpose (KeySelector.Purpose.SIGN, KeySelector.Purpose.VERIFY, KeySelector.Purpose.ENCRYPT, or KeySelector.Purpose.DECRYPT)
    
    method - the algorithm method that this key is to be used for. Only keys that are compatible with the algorithm and meet the constraints of the specified algorithm should be returned.
    
    context - an XMLCryptoContext that may contain useful information for finding an appropriate key. If this key selector supports resolving RetrievalMethod types, the context's baseURI and dereferencer parameters (if specified) should be used by the selector to resolve and dereference the URI.
    
    Returns:
    
    the result of the key selector
    
    Throws:
    
    KeySelectorException - if an exceptional condition occurs while attempting to find a key. Note that an inability to find a key is not considered an exception (null should be returned in that case). However, an error condition (ex: network communications failure) that prevented the KeySelector from finding a potential key should be considered an exception.
    
    ClassCastException - if the data type of method is not supported by this key selector
  - singletonKeySelector
```
public static KeySelector singletonKeySelector(Key key)
```
    Returns a KeySelector that always selects the specified key, regardless of the KeyInfo passed to it.
    
    Parameters:
    
    key - the sole key to be stored in the key selector
    
    Returns:
    
    a key selector that always selects the specified key
    
    Throws:
    
    NullPointerException - if key is null

Nested Class Summary

Constructor Summary

Method Summary

Methods declared in class java.lang.Object

Constructor Detail

KeySelector

Method Detail

select

singletonKeySelector