Package org.apache.mina.filter

Class CompressionFilter

  • All Implemented Interfaces:
    org.apache.mina.common.IoFilter
    public class CompressionFilter
extends org.apache.mina.common.IoFilterAdapter
    An IoFilter which compresses all data using JZlib. Support for the LZW (DLCZ) algorithm is also planned.

    This filter only supports compression using the PARTIAL FLUSH method, since that is the only method useful when doing stream level compression.

    This filter supports compression/decompression of the input and output channels selectively. It can also be enabled/disabled on the fly.

    This filter does not discard the zlib objects, keeping them around for the entire life of the filter. This is because the zlib dictionary needs to be built up over time, which is used during compression and decompression. Over time, as repetitive data is sent over the wire, the compression efficiency steadily increases.

    Note that the zlib header is written only once. It is not necessary that the data received after processing by this filter may not be complete due to packet fragmentation.

    It goes without saying that the other end of this stream should also have a compatible compressor/decompressor using the same algorithm.

    • Nested Class Summary

      • Nested classes/interfaces inherited from interface org.apache.mina.common.IoFilter

        org.apache.mina.common.IoFilter.NextFilter, org.apache.mina.common.IoFilter.WriteRequest

    • Constructor Summary

      Constructors 
      Constructor Description
      CompressionFilter()
      Creates a new instance which compresses outboud data and decompresses inbound data with default compression level.
      CompressionFilter​(boolean compressInbound, boolean compressOutbound, int compressionLevel)
      Creates a new instance.
      CompressionFilter​(int compressionLevel)
      Creates a new instance which compresses outboud data and decompresses inbound data with the specified compressionLevel.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void filterWrite​(org.apache.mina.common.IoFilter.NextFilter nextFilter, org.apache.mina.common.IoSession session, org.apache.mina.common.IoFilter.WriteRequest writeRequest)  
      boolean isCompressInbound()
      Returns true if incoming data is being compressed.
      boolean isCompressOutbound()
      Returns true if the filter is compressing data being written.
      void messageReceived​(org.apache.mina.common.IoFilter.NextFilter nextFilter, org.apache.mina.common.IoSession session, java.lang.Object message)  
      void onPostRemove​(org.apache.mina.common.IoFilterChain parent, java.lang.String name, org.apache.mina.common.IoFilter.NextFilter nextFilter)  
      void onPreAdd​(org.apache.mina.common.IoFilterChain parent, java.lang.String name, org.apache.mina.common.IoFilter.NextFilter nextFilter)  
      void setCompressInbound​(boolean compressInbound)
      Sets if incoming data has to be compressed.
      void setCompressOutbound​(boolean compressOutbound)
      Set if outgoing data has to be compressed.

      • Methods inherited from class org.apache.mina.common.IoFilterAdapter

        destroy, exceptionCaught, filterClose, init, messageSent, onPostAdd, onPreRemove, sessionClosed, sessionCreated, sessionIdle, sessionOpened

      • Methods inherited from class java.lang.Object

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

    • Field Detail

      • COMPRESSION_MAX

        public static final int COMPRESSION_MAX
        Max compression level. Will give the highest compression ratio, but will also take more cpu time and is the slowest.
        See Also:
        Constant Field Values

      • COMPRESSION_MIN

        public static final int COMPRESSION_MIN
        Provides the best speed at the price of a low compression ratio.
        See Also:
        Constant Field Values

      • COMPRESSION_NONE

        public static final int COMPRESSION_NONE
        No compression done on the data.
        See Also:
        Constant Field Values

      • COMPRESSION_DEFAULT

        public static final int COMPRESSION_DEFAULT
        The default compression level used. Provides the best balance between speed and compression
        See Also:
        Constant Field Values

      • DISABLE_COMPRESSION_ONCE

        public static final java.lang.String DISABLE_COMPRESSION_ONCE
        A flag that allows you to disable compression once.

    • Constructor Detail

      • CompressionFilter

        public CompressionFilter()
        Creates a new instance which compresses outboud data and decompresses inbound data with default compression level.

      • CompressionFilter

        public CompressionFilter​(int compressionLevel)
        Creates a new instance which compresses outboud data and decompresses inbound data with the specified compressionLevel.
        Parameters:
        compressionLevel - the level of compression to be used. Must be one of COMPRESSION_DEFAULT, COMPRESSION_MAX, COMPRESSION_MIN, and COMPRESSION_NONE.

      • CompressionFilter

        public CompressionFilter​(boolean compressInbound,
                         boolean compressOutbound,
                         int compressionLevel)
        Creates a new instance.
        Parameters:
        compressInbound - true if data read is to be decompressed
        compressOutbound - true if data written is to be compressed
        compressionLevel - the level of compression to be used. Must be one of COMPRESSION_DEFAULT, COMPRESSION_MAX, COMPRESSION_MIN, and COMPRESSION_NONE.

    • Method Detail

      • messageReceived

        public void messageReceived​(org.apache.mina.common.IoFilter.NextFilter nextFilter,
                            org.apache.mina.common.IoSession session,
                            java.lang.Object message)
                     throws java.lang.Exception
        Specified by:
        messageReceived in interface org.apache.mina.common.IoFilter
        Overrides:
        messageReceived in class org.apache.mina.common.IoFilterAdapter
        Throws:
        java.lang.Exception

      • filterWrite

        public void filterWrite​(org.apache.mina.common.IoFilter.NextFilter nextFilter,
                        org.apache.mina.common.IoSession session,
                        org.apache.mina.common.IoFilter.WriteRequest writeRequest)
                 throws java.io.IOException
        Specified by:
        filterWrite in interface org.apache.mina.common.IoFilter
        Overrides:
        filterWrite in class org.apache.mina.common.IoFilterAdapter
        Throws:
        java.io.IOException

      • onPreAdd

        public void onPreAdd​(org.apache.mina.common.IoFilterChain parent,
                     java.lang.String name,
                     org.apache.mina.common.IoFilter.NextFilter nextFilter)
              throws java.lang.Exception
        Specified by:
        onPreAdd in interface org.apache.mina.common.IoFilter
        Overrides:
        onPreAdd in class org.apache.mina.common.IoFilterAdapter
        Throws:
        java.lang.Exception

      • isCompressInbound

        public boolean isCompressInbound()
        Returns true if incoming data is being compressed.

      • setCompressInbound

        public void setCompressInbound​(boolean compressInbound)
        Sets if incoming data has to be compressed.

      • isCompressOutbound

        public boolean isCompressOutbound()
        Returns true if the filter is compressing data being written.

      • setCompressOutbound

        public void setCompressOutbound​(boolean compressOutbound)
        Set if outgoing data has to be compressed.

      • onPostRemove

        public void onPostRemove​(org.apache.mina.common.IoFilterChain parent,
                         java.lang.String name,
                         org.apache.mina.common.IoFilter.NextFilter nextFilter)
                  throws java.lang.Exception
        Specified by:
        onPostRemove in interface org.apache.mina.common.IoFilter
        Overrides:
        onPostRemove in class org.apache.mina.common.IoFilterAdapter
        Throws:
        java.lang.Exception