Package org.klomp.snark.bencode

Class BDecoder

java.lang.Object
org.klomp.snark.bencode.BDecoder
public class BDecoder
extends Object
Decodes a bencoded stream to BEValues. A bencoded byte stream can represent byte arrays, numbers, lists and maps (dictionaries). It currently contains a hack to indicate a name of a dictionary of which a SHA-1 digest hash should be calculated (the hash over the original bencoded bytes).
Author:
Mark Wielaard (mark@klomp.org).

  • Constructor Summary

    Constructors 
    Constructor Description
    BDecoder​(InputStream in)
    Initalizes a new BDecoder.

  • Method Summary

    Modifier and Type Method Description
    BEValue bdecode()
    Gets the next indicator and returns either null when the stream has ended or bdecodes the rest of the stream and returns the appropriate BEValue encoded object.
    static BEValue bdecode​(InputStream in)
    Creates a new BDecoder and immediatly decodes the first value it sees.
    BEValue bdecodeBytes()
    Returns the next bencoded value on the stream and makes sure it is a byte array.
    BEValue bdecodeList()
    Returns the next bencoded value on the stream and makes sure it is a list.
    BEValue bdecodeMap()
    Returns the next bencoded value on the stream and makes sure it is a map (dictonary).
    BEValue bdecodeNumber()
    Returns the next bencoded value on the stream and makes sure it is a number.
    byte[] get_special_map_digest()
    Ugly hack.
    int getNextIndicator()
    Returns what the next bencoded object will be on the stream or -1 when the end of stream has been reached.
    static void main​(String[] args)
    prints out the decoded data

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • BDecoder

      public BDecoder​(InputStream in)
      Initalizes a new BDecoder. Nothing is read from the given InputStream yet.

  • Method Details

    • get_special_map_digest

      public byte[] get_special_map_digest()
      Ugly hack. Return the SHA has over bytes that make up the special map.
      Returns:
      null if there was no special map

    • bdecode

      public static BEValue bdecode​(InputStream in) throws IOException
      Creates a new BDecoder and immediatly decodes the first value it sees.
      Returns:
      The first BEValue on the stream or null when the stream has ended.
      Throws:
      InvalidBEncodingException - when the stream doesn't start with a bencoded value or the stream isn't a bencoded stream at all.
      IOException - when somthing bad happens with the stream to read from.

    • getNextIndicator

      public int getNextIndicator() throws IOException
      Returns what the next bencoded object will be on the stream or -1 when the end of stream has been reached. Can return something unexpected (not '0' .. '9', 'i', 'l' or 'd') when the stream isn't bencoded. This might or might not read one extra byte from the stream.
      Throws:
      IOException

    • bdecode

      public BEValue bdecode() throws IOException
      Gets the next indicator and returns either null when the stream has ended or bdecodes the rest of the stream and returns the appropriate BEValue encoded object.
      Throws:
      IOException

    • bdecodeBytes

      public BEValue bdecodeBytes() throws IOException
      Returns the next bencoded value on the stream and makes sure it is a byte array. If it is not a bencoded byte array it will throw InvalidBEncodingException.
      Throws:
      IOException

    • bdecodeNumber

      public BEValue bdecodeNumber() throws IOException
      Returns the next bencoded value on the stream and makes sure it is a number. If it is not a number it will throw InvalidBEncodingException.
      Throws:
      IOException

    • bdecodeList

      public BEValue bdecodeList() throws IOException
      Returns the next bencoded value on the stream and makes sure it is a list. If it is not a list it will throw InvalidBEncodingException.
      Throws:
      IOException

    • bdecodeMap

      public BEValue bdecodeMap() throws IOException
      Returns the next bencoded value on the stream and makes sure it is a map (dictonary). If it is not a map it will throw InvalidBEncodingException.
      Throws:
      IOException

    • main

      public static void main​(String[] args)
      prints out the decoded data
      Since:
      0.9.14