# Class AlgorithmParametersSpi

java.lang.Object
java.security.AlgorithmParametersSpi

public abstract class AlgorithmParametersSpi extends Object
This class defines the Service Provider Interface (SPI) for the `AlgorithmParameters` class, which is used to manage algorithm parameters.

All the abstract methods in this class must be implemented by each cryptographic service provider who wishes to supply parameter management for a particular algorithm.

Since:
  1.2
See Also:
  - `AlgorithmParameters`
  - `AlgorithmParameterSpec`
  - `DSAParameterSpec`

## Constructor Summary

Constructors
Constructor
Description
`AlgorithmParametersSpi()`
Constructor for subclasses to call.

## Method Summary

Modifier and Type
Method
Description
`protected abstract byte[]`
`engineGetEncoded()`
Returns the parameters in their primary encoding format.
`protected abstract byte[]`
`engineGetEncoded(String format)`
Returns the parameters encoded in the specified format.
`protected abstract <T extends AlgorithmParameterSpec>
T`
`engineGetParameterSpec(Class<T> paramSpec)`
Returns a (transparent) specification of this parameters object.
`protected abstract void`
`engineInit(byte[] params)`
Imports the specified parameters and decodes them according to the primary decoding format for parameters.
`protected abstract void`
`engineInit(byte[] params, String format)`
Imports the parameters from `params` and decodes them according to the specified decoding format.
`protected abstract void`
`engineInit(AlgorithmParameterSpec paramSpec)`
Initializes this parameters object using the parameters specified in `paramSpec`.
`protected abstract String`
`engineToString()`
Returns a formatted string describing the parameters.

### Methods declared in class Object

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

## Constructor Details

### AlgorithmParametersSpi

public AlgorithmParametersSpi()
Constructor for subclasses to call.

## Method Details

### engineInit

protected abstract void engineInit(AlgorithmParameterSpec paramSpec) throws InvalidParameterSpecException
Initializes this parameters object using the parameters specified in `paramSpec`.

Parameters:
  `paramSpec` - the parameter specification.
Throws:
  `InvalidParameterSpecException` - if the given parameter specification is inappropriate for the initialization of this parameter object.

### engineInit

protected abstract void engineInit(byte[] params) throws IOException
Imports the specified parameters and decodes them according to the primary decoding format for parameters. The primary decoding format for parameters is ASN.1, if an ASN.1 specification for this type of parameters exists.

Parameters:
  `params` - the encoded parameters.
Throws:
  `IOException` - on decoding errors

### engineInit

protected abstract void engineInit(byte[] params, String format) throws IOException
Imports the parameters from `params` and decodes them according to the specified decoding format. If `format` is `null`, the primary decoding format for parameters is used. The primary decoding format is ASN.1, if an ASN.1 specification for these parameters exists.

Parameters:
  `params` - the encoded parameters.
  `format` - the name of the decoding format.
Throws:
  `IOException` - on decoding errors

### engineGetParameterSpec

protected abstract <T extends AlgorithmParameterSpec> T engineGetParameterSpec(Class<T> paramSpec) throws InvalidParameterSpecException
Returns a (transparent) specification of this parameters object. `paramSpec` identifies the specification class in which the parameters should be returned. It could, for example, be `DSAParameterSpec.class`, to indicate that the parameters should be returned in an instance of the `DSAParameterSpec` class.

Type Parameters:
  `T` - the type of the parameter specification to be returned
Parameters:
  `paramSpec` - the specification class in which the parameters should be returned.
Returns:
  the parameter specification.
Throws:
  `InvalidParameterSpecException` - if the requested parameter specification is inappropriate for this parameter object.

### engineGetEncoded

protected abstract byte[] engineGetEncoded() throws IOException
Returns the parameters in their primary encoding format. The primary encoding format for parameters is ASN.1, if an ASN.1 specification for this type of parameters exists.

Returns:
  the parameters encoded using their primary encoding format.
Throws:
  `IOException` - on encoding errors.

### engineGetEncoded

protected abstract byte[] engineGetEncoded(String format) throws IOException
Returns the parameters encoded in the specified format. If `format` is `null`, the primary encoding format for parameters is used. The primary encoding format is ASN.1, if an ASN.1 specification for these parameters exists.

Parameters:
  `format` - the name of the encoding format.
Returns:
  the parameters encoded using the specified encoding scheme.
Throws:
  `IOException` - on encoding errors.

### engineToString

protected abstract String engineToString()
Returns a formatted string describing the parameters.

Returns:
  a formatted string describing the parameters.