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DDTH's Java Common Libraries and Utilities
package com.github.ddth.commons.utils;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import com.google.common.hash.HashCode;
import com.google.common.hash.HashFunction;
import com.google.common.hash.Hasher;
import com.google.common.hash.Hashing;
/**
* Helper class to calculate hash values.
*
* @author Thanh Nguyen
* @since 0.1.0
*/
public class HashUtils {
public final static HashFunction murmur332bit = Hashing.murmur3_32(0);
public final static HashFunction murmur3 = Hashing.murmur3_128(0);
public final static HashFunction crc32 = Hashing.crc32();
public final static HashFunction md5 = Hashing.md5();
public final static HashFunction sha1 = Hashing.sha1();
public final static HashFunction sha256 = Hashing.sha256();
public final static HashFunction sha512 = Hashing.sha512();
public final static HashFunction fastHashFunc = murmur3;
public final static Charset UTF8 = Charset.forName("UTF-8");
/**
* Calculate checksum of an object using Murmur3 hash.
*
* @param obj
* @return
* @see #checksum(Object, HashFunction)
* @since 0.6.3
*/
public static long checksumMurmur3(Object obj) {
return checksum(obj, murmur3);
}
/**
* Calculate checksum of an object using CRC32 hash.
*
* @param obj
* @return
* @see #checksum(Object, HashFunction)
* @since 0.6.3
*/
public static long checksumCrc32(Object obj) {
return checksum(obj, crc32);
}
/**
* Calculate checksum of an object using MD5 hash.
*
* @param obj
* @return
* @see #checksum(Object, HashFunction)
* @since 0.6.3
*/
public static long checksumMd5(Object obj) {
return checksum(obj, md5);
}
/**
* Calculate checksum of an object using SHA1 hash.
*
* @param obj
* @return
* @see #checksum(Object, HashFunction)
* @since 0.6.3
*/
public static long checksumSha1(Object obj) {
return checksum(obj, sha1);
}
/**
* Calculate checksum of an object using SHA256 hash.
*
* @param obj
* @return
* @see #checksum(Object, HashFunction)
* @since 0.6.3
*/
public static long checksumSha256(Object obj) {
return checksum(obj, sha256);
}
/**
* Calculate checksum of an object using SHA512 hash.
*
* @param obj
* @return
* @see #checksum(Object, HashFunction)
* @since 0.6.3
*/
public static long checksumSha512(Object obj) {
return checksum(obj, sha512);
}
/**
* Calculate checksum of an object using default hash function.
*
* @param obj
* @return
* @see #checksum(Object, HashFunction)
* @since 0.6.3
*/
public static long checksum(Object obj) {
return checksum(obj, fastHashFunc);
}
/**
* Calculate checksum of an object, using a supplied hash function.
*
*
* Note: to calculate checksum of a {@link com.fasterxml.jackson.databind.JsonNode}, use
* {@link JacksonUtils#checksum(com.fasterxml.jackson.databind.JsonNode)}
*
*
*
* - Checksum is calculated recursively (if the target object is not scala type).
* - If {@code obj} is {@code null}, {@code 0} is returned.
* - If {@code obj} is wrapper type ({@link Integer}, {@link Long}, {@link Boolean}, etc), or
* {@link String}: hash {@code obj} using the supplied {@code hashFunc} and return the hash
* value as long.
* - If {@code obj} is {@link BigInteger} or {@link BigDecimal}: hash {@code obj.hashCode()}
* using the supplied {@code hashFunc} and return the hash value as long.
* - If {@code obj} is array of primitive types, {@link Object}s or a {@link List}: combine
* each array/list entry's checksum in-order and return the final hash value as long.
* - If {@code obj} is of type {@code Map}: combine each map entry's (key & value) checksum
* un-order and return the final hash value as long.
* - If {@code obj} is of type {@link Collection}: combine each entry's checksum un-order and
* return the final hash value as long.
* - Otherwise, return {@code obj.hashCode()}
*
*
*
* Note:
*
* - {@code Checksum(BigInteger(x))} should NOT be equal to
* {@code Checksum(BigDecimal(x))}
* - {@code Checksum(Double(x))} should be equal to {@code Checksum(Float(x))}
* - {@code Checksum(Byte(x))}, {@code Checksum(Short(x))}, {@code Checksum(Integer(x))} and
* {@code Checksum(Long(x))} should be equal
* - {@code Checksum(int[1,2,3,4])}, {@code Checksum(Long[1,2,3,4])} and
* {@code Checksum(List
[1,2,3,4])} should be equal
* - {@code Checksum(Map[key1=>value1,key2=>value2])} should be equal to
* {@code Checksum(Map[key2=>value2,key1=>value1])}
* - {@code Checksum(non-list-Collection[value1,value2)} should be equal to
* {@code Checksum(non-list-Collection[value2,value1)}
* - {@code Checksum(array[1,2,3,4])} and {@code Checksum(List[1,2,3,4])} should NOT be equal
* to {@code Checksum(non-list-Collection[1,2,3,4)}
*
*
*
* @param obj
* @param hashFunc
* @return
* @since 0.6.3
*/
public static long checksum(Object obj, HashFunction hashFunc) {
if (obj == null) {
return 0;
}
if (obj instanceof Number) {
/*
* BigDecimal & BigInteger should have same checksum value.
* Double & Float should have same checksum value.
* Integers (Byte, Short, Integer, Double) should have same checksum value.
*/
Number num = (Number) obj;
if (num instanceof BigDecimal || num instanceof BigInteger) {
return hashFunc.newHasher().putInt(obj.hashCode()).hash().padToLong();
}
if (num instanceof Double || num instanceof Float) {
return hashFunc.newHasher().putDouble(num.doubleValue()).hash().padToLong();
}
return hashFunc.newHasher().putLong(num.longValue()).hash().padToLong();
}
if (obj instanceof Boolean) {
return hashFunc.newHasher().putBoolean(((Boolean) obj).booleanValue()).hash()
.padToLong();
}
if (obj instanceof Character) {
return hashFunc.newHasher().putChar(((Character) obj).charValue()).hash().padToLong();
}
if (obj instanceof String) {
return hashFunc.newHasher().putString(obj.toString(), UTF8).hash().padToLong();
}
if (obj instanceof byte[] || obj instanceof short[] || obj instanceof int[]
|| obj instanceof long[] || obj instanceof float[] || obj instanceof double[]
|| obj instanceof boolean[] || obj instanceof char[]) {
final Hasher hasher = hashFunc.newHasher();
switch (obj.getClass().getCanonicalName()) {
case "byte[]":
for (byte v : (byte[]) obj) {
hasher.putLong(checksum(v, hashFunc));
// hasher.putByte(v);
}
break;
case "short[]":
for (short v : (short[]) obj) {
hasher.putLong(checksum(v, hashFunc));
// hasher.putShort(v);
}
break;
case "int[]":
for (int v : (int[]) obj) {
hasher.putLong(checksum(v, hashFunc));
// hasher.putInt(v);
}
break;
case "long[]":
for (long v : (long[]) obj) {
hasher.putLong(checksum(v, hashFunc));
// hasher.putLong(v);
}
break;
case "float[]":
for (float v : (float[]) obj) {
hasher.putLong(checksum(v, hashFunc));
// hasher.putFloat(v);
}
break;
case "double[]":
for (double v : (double[]) obj) {
hasher.putLong(checksum(v, hashFunc));
// hasher.putDouble(v);
}
break;
case "boolean[]":
for (boolean v : (boolean[]) obj) {
hasher.putLong(checksum(v, hashFunc));
// hasher.putBoolean(v);
}
break;
case "char[]":
for (char v : (char[]) obj) {
hasher.putLong(checksum(v, hashFunc));
// hasher.putChar(v);
}
break;
default:
throw new IllegalStateException("This should not happen!");
}
return hasher.hash().padToLong();
}
if (obj instanceof Object[]) {
final Hasher hasher = hashFunc.newHasher();
for (Object item : (Object[]) obj) {
hasher.putLong(checksum(item, hashFunc));
}
return hasher.hash().padToLong();
}
if (obj instanceof List) {
final Hasher hasher = hashFunc.newHasher();
for (Object item : (List) obj) {
hasher.putLong(checksum(item, hashFunc));
}
return hasher.hash().padToLong();
}
if (obj instanceof Map) {
final List hashCodes = new ArrayList<>();
for (Entry entry : ((Map) obj).entrySet()) {
hashCodes.add(hashFunc.newHasher().putLong(checksum(entry.getKey(), hashFunc))
.putLong(checksum(entry.getValue(), hashFunc)).hash());
}
return hashCodes.size() > 0 ? Hashing.combineUnordered(hashCodes).padToLong()
: hashFunc.newHasher().hash().padToLong();
}
if (obj instanceof Collection) {
final List hashCodes = new ArrayList<>();
for (Object item : (Collection) obj) {
hashCodes.add(hashFunc.newHasher().putLong(checksum(item, hashFunc)).hash());
}
return hashCodes.size() > 0 ? Hashing.combineUnordered(hashCodes).padToLong()
: hashFunc.newHasher().hash().padToLong();
}
return obj.hashCode();
}
/**
* Calculate hash value of an object using a fast
* non-cryptographic-strength hash function.
*
* @param object
* @return
*/
public static long fastHashValue(Object object) {
if (object == null) {
return 0;
}
HashFunction hashFunction = fastHashFunc;
if (object instanceof Boolean || object instanceof Number || object instanceof String) {
return hashFunction.hashString(object.toString(), UTF8).asLong();
}
return hashFunction.hashInt(object.hashCode()).asLong();
}
/**
* Maps an object to a bucket, using linear hash method.
*
* This method uses a fast non-cryptographic-strength hash function to
* calculate object's hash value.
*
* @param object
* @param numBuckets
* @return the slot index (0 to numSlots-1)
*/
public static long linearHashingMap(Object object, int numBuckets) {
if (numBuckets < 1) {
String msg = "Number of slots must be equal or larger than 1!";
throw new IllegalArgumentException(msg);
}
if (numBuckets == 1 || object == null) {
return 0;
}
return Math.abs(fastHashValue(object) % (long) numBuckets);
}
/**
* Maps an object to a bucket, using consistent hash method.
*
* This method uses a fast non-cryptographic-strength hash function to
* calculate object's hash value.
*
* @param object
* @param numBucket
* @return the slot index (0 to numSlots-1)
*/
public static long consistentHashingMap(Object object, int numBucket) {
if (numBucket < 1) {
String msg = "Number of slots must be equal or larger than 1!";
throw new IllegalArgumentException(msg);
}
if (numBucket == 1 || object == null) {
return 0;
}
long hashValue = fastHashValue(object);
return Hashing.consistentHash(hashValue, numBucket);
}
/**
* Calculate Murmur3-hash value (32-bit) of a string.
*
* @param value
* @return
* @since 0.9.1.1
*/
public static String murmur332bit(String value) {
if (value == null) {
return null;
}
return murmur332bit.hashString(value, UTF8).toString().toLowerCase();
}
/**
* Calculate Murmur3-hash value (32-bit) of a byte array.
*
* @param value
* @return
* @since 0.9.1.1
*/
public static String murmur332bit(byte[] value) {
if (value == null) {
return null;
}
return murmur332bit.hashBytes(value).toString().toLowerCase();
}
/**
* Calculate Murmur3-hash value (128-bit) of a string.
*
* @param value
* @return
* @since 0.6.3
*/
public static String murmur3(String value) {
if (value == null) {
return null;
}
return murmur3.hashString(value, UTF8).toString().toLowerCase();
}
/**
* Calculate Murmur3-hash value (128-bit) of a byte array.
*
* @param value
* @return
* @since 0.6.3
*/
public static String murmur3(byte[] value) {
if (value == null) {
return null;
}
return murmur3.hashBytes(value).toString().toLowerCase();
}
/**
* Calculate CRC32-hash value of a string.
*
* @param value
* @return
*/
public static String crc32(String value) {
if (value == null) {
return null;
}
return crc32.hashString(value, UTF8).toString().toLowerCase();
}
/**
* Calculate CRC32-hash value of a byte array.
*
* @param value
* @return
*/
public static String crc32(byte[] value) {
if (value == null) {
return null;
}
return crc32.hashBytes(value).toString().toLowerCase();
}
/**
* Calculate MD5-hash value of a string.
*
* @param value
* @return
*/
public static String md5(String value) {
if (value == null) {
return null;
}
return md5.hashString(value, UTF8).toString().toLowerCase();
}
/**
* Calculate MD5-hash value of a byte array.
*
* @param value
* @return
*/
public static String md5(byte[] value) {
if (value == null) {
return null;
}
return md5.hashBytes(value).toString().toLowerCase();
}
/**
* Calculate SHA1-hash value of a string.
*
* @param value
* @return
*/
public static String sha1(String value) {
if (value == null) {
return null;
}
return sha1.hashString(value, UTF8).toString().toLowerCase();
}
/**
* Calculate SHA1-hash value of a byte array.
*
* @param value
* @return
*/
public static String sha1(byte[] value) {
if (value == null) {
return null;
}
return sha1.hashBytes(value).toString().toLowerCase();
}
/**
* Calculate SHA256-hash value of a string.
*
* @param value
* @return
*/
public static String sha256(String value) {
if (value == null) {
return null;
}
return sha256.hashString(value, UTF8).toString().toLowerCase();
}
/**
* Calculate SHA256-hash value of a byte array.
*
* @param value
* @return
*/
public static String sha256(byte[] value) {
if (value == null) {
return null;
}
return sha256.hashBytes(value).toString().toLowerCase();
}
/**
* Calculate SHA512-hash value of a string.
*
* @param value
* @return
*/
public static String sha512(String value) {
if (value == null) {
return null;
}
return sha512.hashString(value, UTF8).toString().toLowerCase();
}
/**
* Calculate SHA512-hash value of a byte array.
*
* @param value
* @return
*/
public static String sha512(byte[] value) {
if (value == null) {
return null;
}
return sha512.hashBytes(value).toString().toLowerCase();
}
}
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