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Added a Bloomfilter and fixed some bugs

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Ziver Koc 2009-02-08 21:32:06 +00:00
parent 9e3de28d45
commit 017a27931a
8 changed files with 425 additions and 24 deletions
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97
src/zutil/Hasher.java
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@ -9,10 +9,8 @@ import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import sun.misc.BASE64Encoder;
public class Hasher {
/**
* Returns a hash of a file
*
@ -40,16 +38,46 @@ public class Hasher {
throw new RuntimeException("Unable to process file for MD5", e);
}
is.close();
MultiPrintStream.out.println("File Hash: "+output);
return output;
}
/**
* Returns the MD5 hash of the given object
*
* @param object The object to hash
* @return String containing the hash
*/
public static String MD5(Serializable object){
try {
return hash(object, "MD5");
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
return null;
}
/**
* Returns the SHA-1 hash of the given object
*
* @param object The object to hash
* @return String containing the hash
*/
public static String SHA1(Serializable object){
try {
return hash(object, "SHA-1");
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
return null;
}
/**
* Returns the hash of the given object
*
* @param object The object to hash
* @param hashType The hash method
* @param hashType The hash method (MD2, MD5, SHA-1, SHA-256, SHA-384, SHA-512 )
* @return String containing the hash
* @throws NoSuchAlgorithmException
*/
@ -59,6 +87,61 @@ public class Hasher {
md.update(Converter.toBytes(object));
byte raw[] = md.digest();
return (new BASE64Encoder()).encode(raw);
return Converter.toHexString(raw);//(new BASE64Encoder()).encode(raw);
}
}
/**
* MurmurHash2 ported from cpp source
*
* @param object The Key
* @param seed Seed
* @return A MurmurHash of the key
*/
public static int MurmurHash(Serializable object, int seed){
byte[] data = Converter.toBytes(object);
int length = data.length;
//Constants
int m = 0x5bd1e995;
int r = 24;
// Initialize the hash to a 'random' value
int h = seed ^ length;
int i=0;
for(; i+4<length ;i+=4){
// get the first 4 bytes
int k = data[i+3] & 0xff;
k <<= 8;
k |= data[i+2] & 0xff;
k <<= 8;
k |= data[i+1] & 0xff;
k <<= 8;
k |= data[i+0] & 0xff;
k *= m;
k ^= k >>> r;
k *= m;
h *= m;
h ^= k;
}
// Handle the last few bytes of the input
i = length % 4;
switch(i){
case 3: h ^= data[length-3] << 16;
case 2: h ^= data[length-2] << 8;
case 1: h ^= data[length-1];
h *= m;
}
h ^= h >>> 13;
h *= m;
h ^= h >>> 15;
return h;
}
}