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Java(TM) 2 Platform, Standard Edition, v1.2.2 API Specification: Class CertificateFactory - JDK 5 Documentation v1.2.2, Java 2 SDK 英文文档

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java.security.cert
Class CertificateFactory

java.lang.Object
  |
  +--java.security.cert.CertificateFactory
public class CertificateFactory
extends Object

This class defines the functionality of a certificate factory, which is used to generate certificate and certificate revocation list (CRL) objects from their encodings.

A certificate factory for X.509 must return certificates that are an instance of java.security.cert.X509Certificate, and CRLs that are an instance of java.security.cert.X509CRL.

The following example reads a file with Base64 encoded certificates, which are each bounded at the beginning by -----BEGIN CERTIFICATE-----, and bounded at the end by -----END CERTIFICATE-----. We convert the FileInputStream (which does not support mark and reset) to a ByteArrayInputStream (which supports those methods), so that each call to generateCertificate consumes only one certificate, and the read position of the input stream is positioned to the next certificate in the file:

 FileInputStream fis = new FileInputStream(filename);
 DataInputStream dis = new DataInputStream(fis);

 CertificateFactory cf = CertificateFactory.getInstance("X.509");

 byte[] bytes = new byte[dis.available()];
 dis.readFully(bytes);
 ByteArrayInputStream bais = new ByteArrayInputStream(bytes);

 while (bais.available() > 0) {
    Certificate cert = cf.generateCertificate(bais);
    System.out.println(cert.toString());
 }

The following example parses a PKCS#7-formatted certificate reply stored in a file and extracts all the certificates from it:

 FileInputStream fis = new FileInputStream(filename);
 CertificateFactory cf = CertificateFactory.getInstance("X.509");
 Collection c = cf.generateCertificates(fis);
 Iterator i = c.iterator();
 while (i.hasNext()) {
    Certificate cert = (Certificate)i.next();
    System.out.println(cert);
 }

Since:
JDK1.2
See Also:
Certificate, X509Certificate, CRL, X509CRL

Constructor Summary
protected CertificateFactory(CertificateFactorySpi certFacSpi, Provider provider, String type)
          Creates a CertificateFactory object of the given type, and encapsulates the given provider implementation (SPI object) in it.
 
Method Summary
 Certificate generateCertificate(InputStream inStream)
          Generates a certificate object and initializes it with the data read from the input stream inStream.
 Collection generateCertificates(InputStream inStream)
          Returns a (possibly empty) collection view of the certificates read from the given input stream inStream.
 CRL generateCRL(InputStream inStream)
          Generates a certificate revocation list (CRL) object and initializes it with the data read from the input stream inStream.
 Collection generateCRLs(InputStream inStream)
          Returns a (possibly empty) collection view of the CRLs read from the given input stream inStream.
static CertificateFactory getInstance(String type)
          Generates a certificate factory object that implements the specified certificate type.
static CertificateFactory getInstance(String type, String provider)
          Generates a certificate factory object for the specified certificate type from the specified provider.
 Provider getProvider()
          Returns the provider of this certificate factory.
 String getType()
          Returns the name of the certificate type associated with this certificate factory.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

CertificateFactory

protected CertificateFactory(CertificateFactorySpi certFacSpi,
                             Provider provider,
                             String type)
Creates a CertificateFactory object of the given type, and encapsulates the given provider implementation (SPI object) in it.
Parameters:
certFacSpi - the provider implementation.
provider - the provider.
type - the certificate type.
Method Detail

getInstance

public static final CertificateFactory getInstance(String type)
                                            throws CertificateException
Generates a certificate factory object that implements the specified certificate type. If the default provider package provides an implementation of the requested certificate type, an instance of certificate factory containing that implementation is returned. If the type is not available in the default package, other packages are searched.
Parameters:
type - the name of the requested certificate type. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard certificate types.
Returns:
a certificate factory object for the specified type.
Throws:
CertificateException - if the requested certificate type is not available in the default provider package or any of the other provider packages that were searched.

getInstance

public static final CertificateFactory getInstance(String type,
                                                   String provider)
                                            throws CertificateException,
                                                   NoSuchProviderException
Generates a certificate factory object for the specified certificate type from the specified provider.
Parameters:
type - the certificate type
provider - the name of the provider.
Returns:
a certificate factory object for the specified type.
Throws:
CertificateException - if the certificate type is not available from the specified provider.
NoSuchProviderException - if the provider has not been configured.
See Also:
Provider

getProvider

public final Provider getProvider()
Returns the provider of this certificate factory.
Returns:
the provider of this certificate factory.

getType

public final String getType()
Returns the name of the certificate type associated with this certificate factory.
Returns:
the name of the certificate type associated with this certificate factory.

generateCertificate

public final Certificate generateCertificate(InputStream inStream)
                                      throws CertificateException
Generates a certificate object and initializes it with the data read from the input stream inStream.

The given input stream inStream must contain a single certificate.

In order to take advantage of the specialized certificate format supported by this certificate factory, the returned certificate object can be typecast to the corresponding certificate class. For example, if this certificate factory implements X.509 certificates, the returned certificate object can be typecast to the X509Certificate class.

In the case of a certificate factory for X.509 certificates, the certificate provided in inStream must be DER-encoded and may be supplied in binary or printable (Base64) encoding. If the certificate is provided in Base64 encoding, it must be bounded at the beginning by -----BEGIN CERTIFICATE-----, and must be bounded at the end by -----END CERTIFICATE-----.

Note that if the given input stream does not support mark and reset, this method will consume the entire input stream.

Parameters:
inStream - an input stream with the certificate data.
Returns:
a certificate object initialized with the data from the input stream.
Throws:
CertificateException - on parsing errors.

generateCertificates

public final Collection generateCertificates(InputStream inStream)
                                      throws CertificateException
Returns a (possibly empty) collection view of the certificates read from the given input stream inStream.

In order to take advantage of the specialized certificate format supported by this certificate factory, each element in the returned collection view can be typecast to the corresponding certificate class. For example, if this certificate factory implements X.509 certificates, the elements in the returned collection can be typecast to the X509Certificate class.

In the case of a certificate factory for X.509 certificates, inStream may contain a sequence of DER-encoded certificates in the formats described for generateCertificate. In addition, inStream may contain a PKCS#7 certificate chain. This is a PKCS#7 SignedData object, with the only significant field being certificates. In particular, the signature and the contents are ignored. This format allows multiple certificates to be downloaded at once. If no certificates are present, an empty collection is returned.

Note that if the given input stream does not support mark and reset, this method will consume the entire input stream.

Parameters:
inStream - the input stream with the certificates.
Returns:
a (possibly empty) collection view of java.security.cert.Certificate objects initialized with the data from the input stream.
Throws:
CertificateException - on parsing errors.

generateCRL

public final CRL generateCRL(InputStream inStream)
                      throws CRLException
Generates a certificate revocation list (CRL) object and initializes it with the data read from the input stream inStream.

In order to take advantage of the specialized CRL format supported by this certificate factory, the returned CRL object can be typecast to the corresponding CRL class. For example, if this certificate factory implements X.509 CRLs, the returned CRL object can be typecast to the X509CRL class.

Note that if the given input stream does not support mark and reset, this method will consume the entire input stream.

Parameters:
inStream - an input stream with the CRL data.
Returns:
a CRL object initialized with the data from the input stream.
Throws:
CRLException - on parsing errors.

generateCRLs

public final Collection generateCRLs(InputStream inStream)
                              throws CRLException
Returns a (possibly empty) collection view of the CRLs read from the given input stream inStream.

In order to take advantage of the specialized CRL format supported by this certificate factory, each element in the returned collection view can be typecast to the corresponding CRL class. For example, if this certificate factory implements X.509 CRLs, the elements in the returned collection can be typecast to the X509CRL class.

In the case of a certificate factory for X.509 CRLs, inStream may contain a sequence of DER-encoded CRLs. In addition, inStream may contain a PKCS#7 CRL set. This is a PKCS#7 SignedData object, with the only significant field being crls. In particular, the signature and the contents are ignored. This format allows multiple CRLs to be downloaded at once. If no CRLs are present, an empty collection is returned.

Note that if the given input stream does not support mark and reset, this method will consume the entire input stream.

Parameters:
inStream - the input stream with the CRLs.
Returns:
a (possibly empty) collection view of java.security.cert.CRL objects initialized with the data from the input stream.
Throws:
CRLException - on parsing errors.
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