Package org.apache.tomcat.util.http

Class MimeHeaders

  • public class MimeHeaders
extends java.lang.Object
    Memory-efficient repository for Mime Headers. When the object is recycled, it will keep the allocated headers[] and all the MimeHeaderField - no GC is generated. For input headers it is possible to use the MessageByte for Fields - so no GC will be generated. The only garbage is generated when using the String for header names/values - this can't be avoided when the servlet calls header methods, but is easy to avoid inside tomcat. The goal is to use _only_ MessageByte-based Fields, and reduce to 0 the memory overhead of tomcat. TODO: XXX one-buffer parsing - for http ( other protocols don't need that ) XXX remove unused methods XXX External enumerations, with 0 GC. XXX use HeaderName ID
    Author:
    dac@eng.sun.com, James Todd [gonzo@eng.sun.com], Costin Manolache, kevin seguin

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static int DEFAULT_HEADER_SIZE
      Initial size - should be == average number of headers per request XXX make it configurable ( fine-tuning of web-apps )

    • Constructor Summary

      Constructors 
      Constructor Description
      MimeHeaders()
      Creates a new MimeHeaders object using a default buffer size.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      MessageBytes addValue​(byte[] b, int startN, int len)
      Create a new named header using un-translated byte[].
      MessageBytes addValue​(java.lang.String name)
      Create a new named header , return the MessageBytes container for the new value
      void clear()
      Clears all header fields.
      void duplicate​(MimeHeaders source)  
      int findHeader​(java.lang.String name, int starting)
      Find the index of a header with the given name.
      java.lang.String getHeader​(java.lang.String name)  
      MessageBytes getName​(int n)  
      MessageBytes getUniqueValue​(java.lang.String name)
      Finds and returns a unique header field with the given name.
      MessageBytes getValue​(int n)  
      MessageBytes getValue​(java.lang.String name)
      Finds and returns a header field with the given name.
      java.util.Enumeration<java.lang.String> names()
      Returns an enumeration of strings representing the header field names.
      void recycle()
      Clears all header fields.
      void removeHeader​(int idx)
      Reset, move to the end and then reduce count by 1.
      void removeHeader​(java.lang.String name)
      Removes a header field with the specified name.
      void setLimit​(int limit)
      Set limit on the number of header fields.
      MessageBytes setValue​(java.lang.String name)
      Allow "set" operations, which removes all current values for this header.
      int size()  
      java.lang.String toString()
      EXPENSIVE!!!
      java.util.Enumeration<java.lang.String> values​(java.lang.String name)  

      • Methods inherited from class java.lang.Object

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

    • Field Detail

      • DEFAULT_HEADER_SIZE

        public static final int DEFAULT_HEADER_SIZE
        Initial size - should be == average number of headers per request XXX make it configurable ( fine-tuning of web-apps )
        See Also:
        Constant Field Values

    • Constructor Detail

      • MimeHeaders

        public MimeHeaders()
        Creates a new MimeHeaders object using a default buffer size.

    • Method Detail

      • setLimit

        public void setLimit​(int limit)
        Set limit on the number of header fields.
        Parameters:
        limit - The new limit

      • recycle

        public void recycle()
        Clears all header fields.

      • clear

        public void clear()
        Clears all header fields.

      • toString

        public java.lang.String toString()
        EXPENSIVE!!! only for debugging.
        Overrides:
        toString in class java.lang.Object

      • duplicate

        public void duplicate​(MimeHeaders source)
               throws java.io.IOException
        Throws:
        java.io.IOException

      • size

        public int size()
        Returns:
        the current number of header fields.

      • getName

        public MessageBytes getName​(int n)
        Parameters:
        n - The header index
        Returns:
        the Nth header name, or null if there is no such header. This may be used to iterate through all header fields.

      • getValue

        public MessageBytes getValue​(int n)
        Parameters:
        n - The header index
        Returns:
        the Nth header value, or null if there is no such header. This may be used to iterate through all header fields.

      • findHeader

        public int findHeader​(java.lang.String name,
                      int starting)
        Find the index of a header with the given name.
        Parameters:
        name - The header name
        starting - Index on which to start looking
        Returns:
        the header index

      • names

        public java.util.Enumeration<java.lang.String> names()
        Returns an enumeration of strings representing the header field names. Field names may appear multiple times in this enumeration, indicating that multiple fields with that name exist in this header.
        Returns:
        the enumeration

      • values

        public java.util.Enumeration<java.lang.String> values​(java.lang.String name)

      • addValue

        public MessageBytes addValue​(java.lang.String name)
        Create a new named header , return the MessageBytes container for the new value
        Parameters:
        name - The header name
        Returns:
        the message bytes container for the value

      • addValue

        public MessageBytes addValue​(byte[] b,
                             int startN,
                             int len)
        Create a new named header using un-translated byte[]. The conversion to chars can be delayed until encoding is known.
        Parameters:
        b - The header name bytes
        startN - Offset
        len - Length
        Returns:
        the message bytes container for the value

      • setValue

        public MessageBytes setValue​(java.lang.String name)
        Allow "set" operations, which removes all current values for this header.
        Parameters:
        name - The header name
        Returns:
        the message bytes container for the value

      • getValue

        public MessageBytes getValue​(java.lang.String name)
        Finds and returns a header field with the given name. If no such field exists, null is returned. If more than one such field is in the header, an arbitrary one is returned.
        Parameters:
        name - The header name
        Returns:
        the value

      • getUniqueValue

        public MessageBytes getUniqueValue​(java.lang.String name)
        Finds and returns a unique header field with the given name. If no such field exists, null is returned. If the specified header field is not unique then an IllegalArgumentException is thrown.
        Parameters:
        name - The header name
        Returns:
        the value if unique
        Throws:
        java.lang.IllegalArgumentException - if the header has multiple values

      • getHeader

        public java.lang.String getHeader​(java.lang.String name)

      • removeHeader

        public void removeHeader​(java.lang.String name)
        Removes a header field with the specified name. Does nothing if such a field could not be found.
        Parameters:
        name - the name of the header field to be removed

      • removeHeader

        public void removeHeader​(int idx)
        Reset, move to the end and then reduce count by 1.
        Parameters:
        idx - the index of the header to remove.