Package net.sf.jasperreports.engine.util

Class JRSwapFile

  • Direct Known Subclasses:
    JRConcurrentSwapFile
    public class JRSwapFile
extends java.lang.Object
    Swap file implementation that can be used as a disk cache for arbitrary binary data.

    Fixed-size blocks are allocated inside the swap file when a caller wants to write data. The caller receives a handle to the allocated area based on which it can read the data or free the area.

    The implementation is thread-safe. I/O operations are performed in synchronized blocks, only one thread would do a read or write at one moment.

    Author:
    Lucian Chirita (lucianc@users.sourceforge.net)

    • Field Summary

      Fields 
      Modifier and Type Field Description
      protected java.io.RandomAccessFile file  
      static java.lang.String PROPERTY_DELETE_ON_EXIT
      Property that instructs whether deleteOnExit is to be requested for swap files.
      protected java.io.File swapFile  

    • Constructor Summary

      Constructors 
      Constructor Description
      JRSwapFile​(java.lang.String directory, int blockSize, int minGrowCount)
      Creates a swap file.
      JRSwapFile​(JasperReportsContext jasperReportsContext, java.lang.String directory, int blockSize, int minGrowCount)
      Creates a swap file.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void dispose()
      Closes and deletes the swap file.
      protected void finalize()  
      void free​(JRSwapFile.SwapHandle handle)
      Frees an allocated area.
      protected void freeBlocks​(long[] offsets)  
      protected void read​(byte[] data, int dataOffset, int dataLength, long fileOffset)  
      byte[] read​(JRSwapFile.SwapHandle handle, boolean free)
      Reads all the data from an allocated area.
      protected long[] reserveFreeBlocks​(int blockCount)  
      java.lang.String toString()  
      JRSwapFile.SwapHandle write​(byte[] data)
      Allocates an area in the swap file and writes data in it.
      protected void write​(byte[] data, int dataSize, int dataOffset, long fileOffset)  

      • Methods inherited from class java.lang.Object

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

    • Field Detail

      • PROPERTY_DELETE_ON_EXIT

        public static final java.lang.String PROPERTY_DELETE_ON_EXIT
        Property that instructs whether deleteOnExit is to be requested for swap files. Swap files are explicitly deleted on dispose() and garbage collection.
        See Also:
        Constant Field Values

      • swapFile

        protected final java.io.File swapFile

      • file

        protected final java.io.RandomAccessFile file

    • Constructor Detail

      • JRSwapFile

        public JRSwapFile​(java.lang.String directory,
                  int blockSize,
                  int minGrowCount)
        Creates a swap file. The file name is generated automatically.
        Parameters:
        directory - the directory where the file should be created.
        blockSize - the size of the blocks allocated by the swap file
        minGrowCount - the minimum number of blocks by which the swap file grows when full

      • JRSwapFile

        public JRSwapFile​(JasperReportsContext jasperReportsContext,
                  java.lang.String directory,
                  int blockSize,
                  int minGrowCount)
        Creates a swap file. The file name is generated automatically.
        Parameters:
        jasperReportsContext - the JasperReportsContext to read configuration from.
        directory - the directory where the file should be created.
        blockSize - the size of the blocks allocated by the swap file
        minGrowCount - the minimum number of blocks by which the swap file grows when full

    • Method Detail

      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object

      • write

        public JRSwapFile.SwapHandle write​(byte[] data)
                            throws java.io.IOException
        Allocates an area in the swap file and writes data in it.
        Parameters:
        data - the data for which to allocate an area in the file
        Returns:
        a handle to the allocated area
        Throws:
        java.io.IOException

      • write

        protected void write​(byte[] data,
                     int dataSize,
                     int dataOffset,
                     long fileOffset)
              throws java.io.IOException
        Throws:
        java.io.IOException

      • read

        public byte[] read​(JRSwapFile.SwapHandle handle,
                   boolean free)
            throws java.io.IOException
        Reads all the data from an allocated area.
        Parameters:
        handle - the allocated area handle
        free - whether to free the area after reading
        Returns:
        the whole data saved in an allocated area
        Throws:
        java.io.IOException

      • read

        protected void read​(byte[] data,
                    int dataOffset,
                    int dataLength,
                    long fileOffset)
             throws java.io.IOException
        Throws:
        java.io.IOException

      • free

        public void free​(JRSwapFile.SwapHandle handle)
        Frees an allocated area.
        Parameters:
        handle - the allocated area handle

      • dispose

        public void dispose()
        Closes and deletes the swap file.

      • finalize

        protected void finalize()
                 throws java.lang.Throwable
        Overrides:
        finalize in class java.lang.Object
        Throws:
        java.lang.Throwable

      • reserveFreeBlocks

        protected long[] reserveFreeBlocks​(int blockCount)
                            throws java.io.IOException
        Throws:
        java.io.IOException

      • freeBlocks

        protected void freeBlocks​(long[] offsets)