MD5 Hashing utility that builds up a hash from a series of objects and base types fed into it.
/*
* Copyright 2008-2010 Bay Area Software, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
//package com.bayareasoftware.chartengine.util;
import java.nio.ByteBuffer;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.sql.Timestamp;
import java.util.Arrays;
/**
* MD5 Hashing utility that builds up a hash from a series of objects and base types fed into it.
*
* To use this class the Hash object and then call update() with various objects. Finally use, getBytes() of toHexString() to get out the hash value
*/
public final class Hash {
private final MessageDigest md;
private byte[] bytes;
public Hash() {
try {
md = MessageDigest.getInstance("MD5");
} catch (NoSuchAlgorithmException e) {
throw new IllegalStateException("MD5 algorithm not found", e);
}
}
public Hash(byte[] b) { this(); update(b); }
public Hash(byte[] b, int off, int len) { this(); update(b, off, len); }
public Hash(ByteBuffer bb) { this(); update(bb); }
public Hash(String s) { this(); update(s); }
public Hash(char c) { this(); update(c); }
public Hash(short s) { this(); update(s); }
public Hash(int i) { this(); update(i); }
public Hash(long l) { this(); update(l); }
public Hash(float f) { this(); update(f); }
public Hash(double d) { this(); update(d); }
public Hash update(byte b) {
checkNotFinished();
md.update(b);
return this;
}
public Hash update(byte[] b) {
return update(b, 0, b.length);
}
public Hash update(byte[] b, int off, int len) {
checkNotFinished();
md.update(b, off, len);
return this;
}
public Hash update(ByteBuffer bb) {
checkNotFinished();
md.update(bb);
return this;
}
public Hash update(String s) {
if (s != null) {
for (int i = 0; i < s.length(); i++) {
update(s.charAt(i));
}
}
return this;
}
public Hash update(short s) {
return update((byte) (s >> 8)).update((byte) s);
}
public Hash update(char c) {
return update((short) c);
}
public Hash update(int i) {
return update((short) (i >> 16)).update((short) i);
}
public Hash update(long l) {
return update((int) (l >> 32)).update((int) l);
}
public Hash update(float f) {
return update((Float.floatToRawIntBits(f)));
}
public Hash update(double d) {
return update((Double.doubleToRawLongBits(d)));
}
public Hash update(Timestamp t) {
// FIXME: is this unique enough?
return update(t.getTime());
}
public Hash finish() {
bytes = md.digest();
return this;
}
public void reset() {
bytes = null;
}
public byte[] getBytes() {
ensureFinished();
return bytes;
}
public String toHexString() {
ensureFinished();
StringBuilder sb = new StringBuilder(bytes.length * 2);
for (byte b : bytes) {
sb.append(Character.forDigit((b >> 8) & 0xf, 16));
sb.append(Character.forDigit(b & 0xf, 16));
}
return sb.toString();
}
public boolean equals(Object obj) {
if (this == obj) return true;
if (obj == null || !(obj instanceof Hash)) return false;
Hash hash = (Hash) obj;
return Arrays.equals(getBytes(), hash.getBytes());
}
public int hashCode() {
byte[] b = getBytes();
return (b[0] << 24) | (b[1] << 16) | (b[2] << 8) | b[3];
}
public String toString() {
return toHexString();
}
private void checkNotFinished() {
if (bytes != null) {
throw new IllegalStateException("Hash must be reset before resuse");
}
}
private void ensureFinished() {
if (bytes == null) finish();
}
}
Related examples in the same category
