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added a decoder class for Bencoding

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git-svn-id: https://svn.berlios.de/svnroot/repos/yacy/trunk@6544 6c8d7289-2bf4-0310-a012-ef5d649a1542
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orbiter 15 years ago
parent 04d91c67d6
commit d0b7bf9ca2
1 changed files with 250 additions and 0 deletions
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source/net/yacy/kelondro/util/BDecoder.java
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// BDecoder.java
// -----------------------
// part of YaCy
// (C) by Michael Peter Christen; mc@yacy.net
// first published on http://www.anomic.de
// Frankfurt, Germany, 2010
// Created 03.01.2010
//
// this is an BDecoder implementation according to http://wiki.theory.org/BitTorrentSpecification
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
package net.yacy.kelondro.util;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
public class BDecoder {
private byte[] b;
private int pos;
public BDecoder(byte[] b) {
this.b = b;
this.pos = 0;
}
public enum BType {
string, integer, list, dictionary;
}
public interface BObject {
public BType getType();
public String getString();
public long getInteger();
public List<BObject> getList();
public Map<String, BObject> getMap();
public String toString();
}
public class BDfltObject implements BObject {
public long getInteger() {
throw new UnsupportedOperationException();
}
public List<BObject> getList() {
throw new UnsupportedOperationException();
}
public Map<String, BObject> getMap() {
throw new UnsupportedOperationException();
}
public String getString() {
throw new UnsupportedOperationException();
}
public BType getType() {
throw new UnsupportedOperationException();
}
public String toString() {
throw new UnsupportedOperationException();
}
}
public class BStringObject extends BDfltObject implements BObject {
String s;
public BStringObject(String s) {
this.s = s;
}
public BType getType() {
return BType.string;
}
public String getString() {
return this.s;
}
public String toString() {
return this.s;
}
}
public class BListObject extends BDfltObject implements BObject {
List<BObject> l;
public BListObject(List<BObject> l) {
this.l = l;
}
public BType getType() {
return BType.list;
}
public List<BObject> getList() {
return this.l;
}
public String toString() {
StringBuilder s = new StringBuilder();
s.append("[");
for (BObject o: l) s.append(o.toString()).append(",");
s.setLength(s.length() - 1);
s.append("]");
return s.toString();
}
}
public class BDictionaryObject extends BDfltObject implements BObject {
Map<String, BObject> m;
public BDictionaryObject(Map<String, BObject> m) {
this.m = m;
}
public BType getType() {
return BType.dictionary;
}
public Map<String, BObject> getMap() {
return this.m;
}
public String toString() {
StringBuilder s = new StringBuilder();
s.append("{");
for (Map.Entry<String, BObject> e: m.entrySet()) s.append(e.getKey()).append(":").append(e.getValue().toString()).append(",");
s.setLength(s.length() - 1);
s.append("}");
return s.toString();
}
}
public class BIntegerObject extends BDfltObject implements BObject {
long i;
public BIntegerObject(long i) {
this.i = i;
}
public BType getType() {
return BType.integer;
}
public long getInteger() {
return this.i;
}
public String toString() {
return Long.toString(this.i);
}
}
private Map<String, BObject> convertToMap(final List<BObject> list) {
final Map<String, BObject> m = new LinkedHashMap<String, BObject>();
final int length = list.size();
for (int i = 0; i < length; i += 2) {
final String key = list.get(i).getString();
BObject value = null;
if (i + 1 < length) {
value = list.get(i + 1);
}
m.put(key, value);
}
return m;
}
private List<BObject> readList() {
final List<BObject> list = new ArrayList<BObject>();
char ch = (char) b[pos];
while (ch != 'e') {
BObject bo = parse();
if (bo == null) {pos++; break;}
list.add(bo);
ch = (char) b[pos];
}
pos++;
return list;
}
public BObject parse() {
if (pos >= b.length) return null;
char ch = (char) b[pos];
if ((ch >= '0') && (ch <= '9')) {
int end = pos;
end++;
while (b[end] != ':') ++end;
final int len = Integer.parseInt(new String(b, pos, end - pos));
final String str = new String(b, end + 1, len);
pos = end + len + 1;
return new BStringObject(str);
} else if (ch == 'l') {
pos++;
return new BListObject(readList());
} else if (ch == 'd') {
pos++;
return new BDictionaryObject(convertToMap(readList()));
} else if (ch == 'i') {
pos++;
int end = pos;
while (b[end] != 'e') ++end;
BIntegerObject io = new BIntegerObject(Long.parseLong(new String(b, pos, end - pos)));
pos = end + 1;
return io;
} else {
return null;
}
}
public static void print(BObject bo, int t) {
for (int i = 0; i < t; i++) System.out.print(" ");
if (bo.getType() == BType.integer) System.out.println(bo.getInteger());
if (bo.getType() == BType.string) System.out.println(bo.getString());
if (bo.getType() == BType.list) {
System.out.println("[");
//for (int i = 0; i < t + 1; i++) System.out.print(" ");
for (BObject o: bo.getList()) print(o, t + 1);
for (int i = 0; i < t; i++) System.out.print(" ");
System.out.println("]");
}
if (bo.getType() == BType.dictionary) {
System.out.println("{");
for (Map.Entry<String, BObject> e: bo.getMap().entrySet()) {
for (int i = 0; i < t + 1; i++) System.out.print(" ");
System.out.print(e.getKey());
System.out.println(":");
print(e.getValue(), t + 2);
}
for (int i = 0; i < t; i++) System.out.print(" ");
System.out.println("}");
}
}
public static void main(String[] args) {
try {
byte[] b = FileUtils.read(new File(args[0]));
BDecoder bdecoder = new BDecoder(b);
BObject o = bdecoder.parse();
print(o, 0);
System.out.println("Object: " + o.toString());
} catch (IOException e) {
e.printStackTrace();
}
}
}
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