Package org.restlet.representation

Class DigesterRepresentation

java.lang.Object
org.restlet.representation.Variant
org.restlet.representation.RepresentationInfo
org.restlet.representation.Representation
org.restlet.util.WrapperRepresentation
org.restlet.representation.DigesterRepresentation
public class DigesterRepresentation extends WrapperRepresentation
Representation capable of computing a digest. It wraps another representation and allows to get the computed digest of the wrapped entity after reading or writing operations. The final digest value is guaranteed to be correct only after the wrapped representation has been entirely exhausted (that is to say read or written).

This wrapper allows getting the computed digest at the same time the representation is read or written. It does not need two separate operations which may require specific attention for transient representations.
Author:
Jerome Louvel
See Also:

  • Constructor Details

  • Method Details

    • checkDigest

      public boolean checkDigest()
      Check that the digest computed from the representation content and the digest declared by the representation are the same.
      Since this method relies on the computeDigest(String) method, and since this method reads entirely the representation's stream, user must take care of the content of the representation in case the latter is transient.
      Returns:
      True if both digests are not null and equals.

    • checkDigest

      public boolean checkDigest(String algorithm)
      Check that the digest computed from the representation content and the digest declared by the representation are the same. It also first checks that the algorithms are the same.
      Since this method relies on the computeDigest(String) method, and since this method reads entirely the representation's stream, user must take care of the content of the representation in case the latter is transient.
      Parameters:
      algorithm - The algorithm used to compute the digest to compare with. See constant values in Digest.
      Returns:
      True if both digests are not null and equals.

    • computeDigest

      public Digest computeDigest()
      Compute the representation digest according to MD5 algorithm.
      If case this algorithm is the same as the one provided at instantiation, the computation operation is made with the current stored computed value and does not require to entirely exhaust the representation's stream.

    • computeDigest

      public Digest computeDigest(String algorithm)
      Compute the representation digest according to the given algorithm.
      Since this method entirely reads the representation stream, user must take care of the content of the representation in case the latter is transient.
      Parameters:
      algorithm - The algorithm used to compute the digest. See constant values in Digest.
      Returns:
      The computed digest or null if the digest cannot be computed.

    • exhaust

      public long exhaust() throws IOException
      Exhausts the content of the representation by reading it and silently discarding anything read.
      Overrides:
      exhaust in class WrapperRepresentation
      Returns:
      The number of bytes consumed or -1 if unknown.
      Throws:
      IOException

    • getComputedDigest

      public Digest getComputedDigest()
      Returns the current computed digest value of the representation. User must be aware that, if the representation has not been entirely read or written, the computed digest value may not be accurate.
      Returns:
      The current computed digest value.

    • getReader

      public Reader getReader() throws IOException
      Description copied from class: Representation
      Returns a character reader with the representation's content. This method is ensured to return a fresh reader for each invocation unless it is a transient representation, in which case null is returned. If the representation has no character set defined, the system's default one will be used.
      Overrides:
      getReader in class WrapperRepresentation
      Returns:
      A reader with the representation's content.
      Throws:
      IOException

    • getStream

      public InputStream getStream() throws IOException
      Returns a stream with the representation's content. This method is ensured to return a fresh stream for each invocation unless it is a transient representation, in which case null is returned.
      The stream of the underlying representation is wrapped with a new instance of the DigestInputStream class, which allows to compute progressively the digest value.
      Overrides:
      getStream in class WrapperRepresentation
      Returns:
      A stream with the representation's content.
      Throws:
      IOException

    • getText

      public String getText() throws IOException
      Description copied from class: Representation
      Converts the representation to a string value. Be careful when using this method as the conversion of large content to a string fully stored in memory can result in OutOfMemoryErrors being thrown.
      Overrides:
      getText in class WrapperRepresentation
      Returns:
      The representation as a string value.
      Throws:
      IOException

    • write

      public void write(OutputStream outputStream) throws IOException
      Writes the representation to a byte stream. This method is ensured to write the full content for each invocation unless it is a transient representation, in which case an exception is thrown.

      Note that the class implementing this method shouldn't flush or close the given OutputStream after writing to it as this will be handled by the Restlet connectors automatically.
      The output stream is wrapped with a new instance of the DigestOutputStream class, which allows to compute progressively the digest value.
      Overrides:
      write in class WrapperRepresentation
      Parameters:
      outputStream - The output stream.
      Throws:
      IOException

    • write

      public void write(Writer writer) throws IOException
      Description copied from class: Representation
      Writes the representation to a characters writer. This method is ensured to write the full content for each invocation unless it is a transient representation, in which case an exception is thrown.

      Note that the class implementing this method shouldn't flush or close the given Writer after writing to it as this will be handled by the Restlet connectors automatically.
      Overrides:
      write in class WrapperRepresentation
      Parameters:
      writer - The characters writer.
      Throws:
      IOException