Interface Buf

All Known Implementing Classes:
BankBuf, SimpleNioBuf, WrapperBuf

public interface Buf
Represents a sequence of bytes along with operations to read primitive values from it. This interface abstracts away implementation details such as storage mechanism, data encoding and pointer length. It is capable of dealing with 64-bit lengths and offsets. All of the read* methods are safe for use from multiple threads concurrently.
Since:
18 Jun 2013
  • Method Summary

    Modifier and Type
    Method
    Description
    createInputStream(long offset)
    Returns an input stream consisting of all the bytes in this buf starting from the given offset.
    fillNewBuf(long count, InputStream in)
    Creates a new Buf of a given length populated from a given input stream.
    long
    Returns the extent of this buf in bytes.
    boolean
    Determines the data encoding of this buf.
    boolean
    Determines the 64bit-ness of this buf.
    readAsciiString(Pointer ptr, int nbyte)
    Reads a fixed number of bytes interpreting them as ASCII characters and returns the result as a string.
    void
    readDataBytes(long offset, int count, byte[] array)
    Reads a sequence of byte values from this buf into an array.
    void
    readDataDoubles(long offset, int count, double[] array)
    Reads a sequence of double values from this buf into an array.
    void
    readDataFloats(long offset, int count, float[] array)
    Reads a sequence of float values from this buf into an array.
    void
    readDataInts(long offset, int count, int[] array)
    Reads a sequence of int values from this buf into an array.
    void
    readDataLongs(long offset, int count, long[] array)
    Reads a sequence of long integer values from this buf into an array.
    void
    readDataShorts(long offset, int count, short[] array)
    Reads a sequence of short values from this buf into an array.
    int
    Reads a signed big-endian 4-byte integer from the pointer position.
    long
    Reads a file offset or size from the pointer position.
    int
    Reads a single byte from the pointer position, returning a value in the range 0..255.
    void
    setBit64(boolean isBit64)
    Sets the 64bit-ness of this buf.
    void
    setEncoding(boolean isBigendian)
    Sets the encoding for reading numeric values as performed by the readData* methods.
  • Method Details

    • getLength

      long getLength()
      Returns the extent of this buf in bytes.
      Returns:
      buffer length
    • readUnsignedByte

      int readUnsignedByte(Pointer ptr) throws IOException
      Reads a single byte from the pointer position, returning a value in the range 0..255. Pointer position is moved on appropriately.
      Parameters:
      ptr - pointer
      Returns:
      byte value
      Throws:
      IOException
    • readInt

      int readInt(Pointer ptr) throws IOException
      Reads a signed big-endian 4-byte integer from the pointer position. Pointer position is moved on appropriately.
      Parameters:
      ptr - pointer
      Returns:
      integer value
      Throws:
      IOException
    • readOffset

      long readOffset(Pointer ptr) throws IOException
      Reads a file offset or size from the pointer position. This is a signed big-endian integer, occupying either 4 or 8 bytes according to the return value of isBit64(). Pointer position is moved on appropriately.
      Returns:
      buffer size or offset value
      Throws:
      IOException
    • readAsciiString

      String readAsciiString(Pointer ptr, int nbyte) throws IOException
      Reads a fixed number of bytes interpreting them as ASCII characters and returns the result as a string. If a character 0x00 appears before nbyte bytes have been read, it is taken as the end of the string. Pointer position is moved on appropriately.
      Parameters:
      ptr - pointer
      nbyte - maximum number of bytes in string
      Returns:
      ASCII string
      Throws:
      IOException
    • setBit64

      void setBit64(boolean isBit64)
      Sets the 64bit-ness of this buf. This determines whether readOffset reads 4- or 8-byte values.

      This method should be called before the readOffset method is invoked.

      Parameters:
      isBit64 - true for 8-byte offsets, false for 4-byte offsets
    • isBit64

      boolean isBit64()
      Determines the 64bit-ness of this buf. This determines whether readOffset reads 4- or 8-byte values.
      Returns:
      true for 8-byte offsets, false for 4-byte offsets
    • setEncoding

      void setEncoding(boolean isBigendian)
      Sets the encoding for reading numeric values as performed by the readData* methods.

      As currently specified, there are only two possibiliies, Big-Endian and Little-Endian. Interface and implementation would need to be reworked somewhat to accommodate the (presumably, rarely seen in this day and age) D_FLOAT and G_FLOAT encodings supported by the CDF standard.

      This method should be called before any of the readData* methods are invoked.

      Parameters:
      isBigendian - true for big-endian, false for little-endian
    • isBigendian

      boolean isBigendian()
      Determines the data encoding of this buf.
      Returns:
      true for big-endian, false for little-endian
    • readDataBytes

      void readDataBytes(long offset, int count, byte[] array) throws IOException
      Reads a sequence of byte values from this buf into an array.
      Parameters:
      offset - position sequence start in this buffer in bytes
      count - number of byte values to read
      array - array to receive values, starting at array element 0
      Throws:
      IOException
    • readDataShorts

      void readDataShorts(long offset, int count, short[] array) throws IOException
      Reads a sequence of short values from this buf into an array.
      Parameters:
      offset - position sequence start in this buffer in bytes
      count - number of short values to read
      array - array to receive values, starting at array element 0
      Throws:
      IOException
    • readDataInts

      void readDataInts(long offset, int count, int[] array) throws IOException
      Reads a sequence of int values from this buf into an array.
      Parameters:
      offset - position sequence start in this buffer in bytes
      count - number of int values to read
      array - array to receive values, starting at array element 0
      Throws:
      IOException
    • readDataLongs

      void readDataLongs(long offset, int count, long[] array) throws IOException
      Reads a sequence of long integer values from this buf into an array.
      Parameters:
      offset - position sequence start in this buffer in bytes
      count - number of long values to read
      array - array to receive values, starting at array element 0
      Throws:
      IOException
    • readDataFloats

      void readDataFloats(long offset, int count, float[] array) throws IOException
      Reads a sequence of float values from this buf into an array.
      Parameters:
      offset - position sequence start in this buffer in bytes
      count - number of float values to read
      array - array to receive values, starting at array element 0
      Throws:
      IOException
    • readDataDoubles

      void readDataDoubles(long offset, int count, double[] array) throws IOException
      Reads a sequence of double values from this buf into an array.
      Parameters:
      offset - position sequence start in this buffer in bytes
      count - number of double values to read
      array - array to receive values, starting at array element 0
      Throws:
      IOException
    • createInputStream

      InputStream createInputStream(long offset)
      Returns an input stream consisting of all the bytes in this buf starting from the given offset.
      Parameters:
      offset - position of first byte in buf that will appear in the returned stream
      Returns:
      input stream
    • fillNewBuf

      Buf fillNewBuf(long count, InputStream in) throws IOException
      Creates a new Buf of a given length populated from a given input stream. The new buf object must have the same data encoding and 64bit-ness as this one.
      Parameters:
      count - size of new buffer in bytes
      in - input stream capable of supplying (at least) count bytes
      Returns:
      new buffer of length count filled with bytes from in
      Throws:
      IOException