DigestOutputStream (Java Platform SE 7 ) (original) (raw)

• java.lang.Object

• • java.io.OutputStream
  • • java.io.FilterOutputStream
      • • java.security.DigestOutputStream

• All Implemented Interfaces:
  Closeable, Flushable, AutoCloseable

public class DigestOutputStream
extends FilterOutputStream
A transparent stream that updates the associated message digest using the bits going through the stream.
To complete the message digest computation, call one of thedigest methods on the associated message digest after your calls to one of this digest ouput stream'swrite methods.
It is possible to turn this stream on or off (seeon). When it is on, a call to one of thewrite methods results in an update on the message digest. But when it is off, the message digest is not updated. The default is for the stream to be on.
See Also:
MessageDigest, DigestInputStream

• • Field Summary

  Fields

  Modifier and Type	Field and Description
  protected MessageDigest	digest The message digest associated with this stream.

     * ### Fields inherited from class java.io.[FilterOutputStream](../../java/io/FilterOutputStream.html "class in java.io")  
     `[out](../../java/io/FilterOutputStream.html#out)`  

  • Constructor Summary

  Constructors

  Constructor and Description
  DigestOutputStream(OutputStream stream,MessageDigest digest) Creates a digest output stream, using the specified output stream and message digest.

  • Method Summary

  Methods

  Modifier and Type	Method and Description
  MessageDigest	getMessageDigest() Returns the message digest associated with this stream.
  void	on(boolean on) Turns the digest function on or off.
  void	setMessageDigest(MessageDigest digest) Associates the specified message digest with this stream.
  String	toString() Prints a string representation of this digest output stream and its associated message digest object.
  void	write(byte[] b, int off, int len) Updates the message digest (if the digest function is on) using the specified subarray, and in any case writes the subarray to the output stream.
  void	write(int b) Updates the message digest (if the digest function is on) using the specified byte, and in any case writes the byte to the output stream.

     * ### Methods inherited from class java.io.[FilterOutputStream](../../java/io/FilterOutputStream.html "class in java.io")  
     `[close](../../java/io/FilterOutputStream.html#close%28%29), [flush](../../java/io/FilterOutputStream.html#flush%28%29), [write](../../java/io/FilterOutputStream.html#write%28byte[]%29)`  
     * ### Methods inherited from class java.lang.[Object](../../java/lang/Object.html "class in java.lang")  
     `[clone](../../java/lang/Object.html#clone%28%29), [equals](../../java/lang/Object.html#equals%28java.lang.Object%29), [finalize](../../java/lang/Object.html#finalize%28%29), [getClass](../../java/lang/Object.html#getClass%28%29), [hashCode](../../java/lang/Object.html#hashCode%28%29), [notify](../../java/lang/Object.html#notify%28%29), [notifyAll](../../java/lang/Object.html#notifyAll%28%29), [wait](../../java/lang/Object.html#wait%28%29), [wait](../../java/lang/Object.html#wait%28long%29), [wait](../../java/lang/Object.html#wait%28long,%20int%29)`

• • Field Detail

     * #### digest  
     protected [MessageDigest](../../java/security/MessageDigest.html "class in java.security") digest  
     The message digest associated with this stream.  

  • Constructor Detail

    * #### DigestOutputStream  
    public DigestOutputStream([OutputStream](../../java/io/OutputStream.html "class in java.io") stream,  
                      [MessageDigest](../../java/security/MessageDigest.html "class in java.security") digest)  
    Creates a digest output stream, using the specified output stream and message digest.  
    Parameters:  
    `stream` \- the output stream.  
    `digest` \- the message digest to associate with this stream.  

  • Method Detail

    * #### getMessageDigest  
    public [MessageDigest](../../java/security/MessageDigest.html "class in java.security") getMessageDigest()  
    Returns the message digest associated with this stream.  
    Returns:  
    the message digest associated with this stream.  
    See Also:  
    [setMessageDigest(java.security.MessageDigest)](../../java/security/DigestOutputStream.html#setMessageDigest%28java.security.MessageDigest%29)  
    * #### setMessageDigest  
    public void setMessageDigest([MessageDigest](../../java/security/MessageDigest.html "class in java.security") digest)  
    Associates the specified message digest with this stream.  
    Parameters:  
    `digest` \- the message digest to be associated with this stream.  
    See Also:  
    [getMessageDigest()](../../java/security/DigestOutputStream.html#getMessageDigest%28%29)  
    * #### write  
    public void write(int b)  
               throws [IOException](../../java/io/IOException.html "class in java.io")  
    Updates the message digest (if the digest function is on) using the specified byte, and in any case writes the byte to the output stream. That is, if the digest function is on (see [on](../../java/security/DigestOutputStream.html#on%28boolean%29)), this method calls`update` on the message digest associated with this stream, passing it the byte `b`. This method then writes the byte to the output stream, blocking until the byte is actually written.  
    **Overrides:**  
    `[write](../../java/io/FilterOutputStream.html#write%28int%29)` in class `[FilterOutputStream](../../java/io/FilterOutputStream.html "class in java.io")`  
    Parameters:  
    `b` \- the byte to be used for updating and writing to the output stream.  
    Throws:  
    `[IOException](../../java/io/IOException.html "class in java.io")` \- if an I/O error occurs.  
    See Also:  
    [MessageDigest.update(byte)](../../java/security/MessageDigest.html#update%28byte%29)  
    * #### write  
    public void write(byte[] b,  
             int off,  
             int len)  
               throws [IOException](../../java/io/IOException.html "class in java.io")  
    Updates the message digest (if the digest function is on) using the specified subarray, and in any case writes the subarray to the output stream. That is, if the digest function is on (see[on](../../java/security/DigestOutputStream.html#on%28boolean%29)), this method calls `update` on the message digest associated with this stream, passing it the subarray specifications. This method then writes the subarray bytes to the output stream, blocking until the bytes are actually written.  
    **Overrides:**  
    `[write](../../java/io/FilterOutputStream.html#write%28byte[],%20int,%20int%29)` in class `[FilterOutputStream](../../java/io/FilterOutputStream.html "class in java.io")`  
    Parameters:  
    `b` \- the array containing the subarray to be used for updating and writing to the output stream.  
    `off` \- the offset into `b` of the first byte to be updated and written.  
    `len` \- the number of bytes of data to be updated and written from `b`, starting at offset `off`.  
    Throws:  
    `[IOException](../../java/io/IOException.html "class in java.io")` \- if an I/O error occurs.  
    See Also:  
    [MessageDigest.update(byte\[\], int, int)](../../java/security/MessageDigest.html#update%28byte[],%20int,%20int%29)  
    * #### on  
    public void on(boolean on)  
    Turns the digest function on or off. The default is on. When it is on, a call to one of the `write` methods results in an update on the message digest. But when it is off, the message digest is not updated.  
    Parameters:  
    `on` \- true to turn the digest function on, false to turn it off.  
    * #### toString  
    public [String](../../java/lang/String.html "class in java.lang") toString()  
    Prints a string representation of this digest output stream and its associated message digest object.  
    **Overrides:**  
    `[toString](../../java/lang/Object.html#toString%28%29)` in class `[Object](../../java/lang/Object.html "class in java.lang")`  
    Returns:  
    a string representation of the object.

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