com.cloudhopper.commons.util.HexString Maven / Gradle / Ivy
package com.cloudhopper.commons.util;
/*
* #%L
* ch-commons-util
* %%
* Copyright (C) 2012 Cloudhopper by Twitter
* %%
* 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.
* #L%
*/
import static com.cloudhopper.commons.util.HexUtil.toByteArray;
import static com.cloudhopper.commons.util.HexUtil.toHexString;
import java.util.Arrays;
/**
* Utility class for representing hex strings. Instances are immutable. Hex digits are always in caps.
*
* Primarily used to aid testing, the implementation is naive and not performant.
* NOT RECOMMENDED FOR USE IN PRODUCTION.
*
* @author John Woolf (twitter: @jwoolf330 or http://twitter.com/jwoolf330)
*
*/
public final class HexString {
public static final HexString NULL = new HexString(new byte[0], "");
/**
* Create a new HexString instance from the given hexadecimal string.
* If null or an empty string is passed, will return a HexString instance
* with empty hex value and zero-length byte array.
*
* @param hex The hexadecimal string
* @return Immutable HexString instance encapsulating the hexadecimal string
* @throws IllegalArgumentException if malformed hex string (invalid or odd number of characters) is passed
*/
public static HexString valueOf(String hex) {
return (hex == null || hex.equals("")) ? NULL : createHexString(hex);
}
/**
* Create a new HexString instance from the given byte array.
* If null or zero-length byte array is passed, will return a HexString instance
* with empty hex value and zero-length byte array.
*
* @param bytes The byte array
* @return Immutable HexString instance encapsulating the byte array
*/
public static HexString valueOf(byte[] bytes) {
return (bytes == null || bytes.length == 0) ? NULL : createHexString(bytes);
}
private static HexString createHexString(String hex) { // though method is private, leaving checks in place to show intent
if (hex == null) {
throw new IllegalArgumentException("hex string argument cannot be null; use HexString.NULL instead");
} else if (hex.equals("")) {
throw new IllegalArgumentException("hex string argument cannot be empty; use HexString.NULL instead");
}
byte[] bytes = toByteArray(hex);
return new HexString(bytes, hex.toUpperCase());
}
private static HexString createHexString(byte[] bytes) { // though method is private, leaving checks in place to show intent
if (bytes == null) {
throw new IllegalArgumentException("bytes argument cannot be null; use HexString.NULL instead");
} else if (bytes.length == 0) {
throw new IllegalArgumentException("bytes argument cannot be zero length; use HexString.NULL instead");
}
byte[] copyOfbytes = copyByteArray(bytes);
String hex = toHexString(copyOfbytes).toUpperCase();
return new HexString(copyOfbytes, hex);
}
private static byte[] copyByteArray(byte[] bytes) {
return Arrays.copyOf(bytes, bytes.length);
}
private final String hex;
private final byte[] bytes;
private HexString(byte[] bytes, String hex) {
this.bytes = bytes;
this.hex = hex;
}
/**
* @return The instance as an unformatted hex string - i.e. \"AB45C03F\"
*/
public String asString() {
return hex;
}
/**
* N.B. asBytes() returns a copy of the underlying byte array
*
* @return The instance as its underlying byte array
*/
public byte[] asBytes() {
return copyByteArray(bytes);
}
@Override
public String toString() {
return "0x" + hex;
}
@Override
public boolean equals(Object other) {
if (other != null && other instanceof HexString) {
HexString hexString = (HexString) other;
return this.hex.equals(hexString.hex);
} else {
return false;
}
}
@Override
public int hashCode() {
return this.hex.hashCode();
}
}