Bael 2189: Convert Byte Array To/From hex String (#5396)

* BAEL-2159: Mini Article on "Separate double into integer and decimal parts"

* BAEL-2189: Tutorial to convert Byte Array to/from hex String.

* BEAL-2189: Code review comments incorporated.

* 1. Added validations for Non-Hex String characters in hex String.
2. Moved classes to algorithms module.
3. Renamed unit test class name ends with *UnitTest.

* 1. Added validations for Non-Hex String characters in hex String.
2. Moved classes to algorithms module.
3. Renamed unit test class name ends with *UnitTest.

* removed: redundant property added for local testing.
This commit is contained in:
Akash Pandey 2018-10-13 01:20:33 +05:30 committed by Grzegorz Piwowarek
parent 15b7eacd43
commit fe8488a8d5
3 changed files with 243 additions and 0 deletions

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@ -17,6 +17,11 @@
<artifactId>commons-math3</artifactId>
<version>${commons-math3.version}</version>
</dependency>
<dependency>
<groupId>commons-codec</groupId>
<artifactId>commons-codec</artifactId>
<version>${commons-codec.version}</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
@ -85,6 +90,7 @@
<io.jenetics.version>3.7.0</io.jenetics.version>
<org.jgrapht.core.version>1.0.1</org.jgrapht.core.version>
<org.assertj.core.version>3.9.0</org.assertj.core.version>
<commons-codec.version>1.11</commons-codec.version>
</properties>
</project>

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@ -0,0 +1,110 @@
package com.baeldung.algorithms.conversion;
import java.math.BigInteger;
import javax.xml.bind.DatatypeConverter;
import org.apache.commons.codec.DecoderException;
import org.apache.commons.codec.binary.Hex;
import com.google.common.io.BaseEncoding;
public class HexStringConverter {
/**
* Create a byte Array from String of hexadecimal digits using Character conversion
* @param hexString - Hexadecimal digits as String
* @return Desired byte Array
*/
public byte[] decodeHexString(String hexString) {
if (hexString.length() % 2 == 1) {
throw new IllegalArgumentException("Invalid hexadecimal String supplied.");
}
byte[] bytes = new byte[hexString.length() / 2];
for (int i = 0; i < hexString.length(); i += 2) {
bytes[i / 2] = hexToByte(hexString.substring(i, i + 2));
}
return bytes;
}
/**
* Create a String of hexadecimal digits from a byte Array using Character conversion
* @param byteArray - The byte Array
* @return Desired String of hexadecimal digits in lower case
*/
public String encodeHexString(byte[] byteArray) {
StringBuffer hexStringBuffer = new StringBuffer();
for (int i = 0; i < byteArray.length; i++) {
hexStringBuffer.append(byteToHex(byteArray[i]));
}
return hexStringBuffer.toString();
}
public String byteToHex(byte num) {
char[] hexDigits = new char[2];
hexDigits[0] = Character.forDigit((num >> 4) & 0xF, 16);
hexDigits[1] = Character.forDigit((num & 0xF), 16);
return new String(hexDigits);
}
public byte hexToByte(String hexString) {
int firstDigit = toDigit(hexString.charAt(0));
int secondDigit = toDigit(hexString.charAt(1));
return (byte) ((firstDigit << 4) + secondDigit);
}
private int toDigit(char hexChar) {
int digit = Character.digit(hexChar, 16);
if(digit == -1) {
throw new IllegalArgumentException("Invalid Hexadecimal Character: "+ hexChar);
}
return digit;
}
public String encodeUsingBigIntegerToString(byte[] bytes) {
BigInteger bigInteger = new BigInteger(1, bytes);
return bigInteger.toString(16);
}
public String encodeUsingBigIntegerStringFormat(byte[] bytes) {
BigInteger bigInteger = new BigInteger(1, bytes);
return String.format("%0" + (bytes.length << 1) + "x", bigInteger);
}
public byte[] decodeUsingBigInteger(String hexString) {
byte[] byteArray = new BigInteger(hexString, 16).toByteArray();
if (byteArray[0] == 0) {
byte[] output = new byte[byteArray.length - 1];
System.arraycopy(byteArray, 1, output, 0, output.length);
return output;
}
return byteArray;
}
public String encodeUsingDataTypeConverter(byte[] bytes) {
return DatatypeConverter.printHexBinary(bytes);
}
public byte[] decodeUsingDataTypeConverter(String hexString) {
return DatatypeConverter.parseHexBinary(hexString);
}
public String encodeUsingApacheCommons(byte[] bytes) throws DecoderException {
return Hex.encodeHexString(bytes);
}
public byte[] decodeUsingApacheCommons(String hexString) throws DecoderException {
return Hex.decodeHex(hexString);
}
public String encodeUsingGuava(byte[] bytes) {
return BaseEncoding.base16()
.encode(bytes);
}
public byte[] decodeUsingGuava(String hexString) {
return BaseEncoding.base16()
.decode(hexString.toUpperCase());
}
}

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@ -0,0 +1,127 @@
package com.baeldung.algorithms.conversion;
import static org.junit.Assert.assertArrayEquals;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertThat;
import org.apache.commons.codec.DecoderException;
import org.hamcrest.text.IsEqualIgnoringCase;
import org.junit.Before;
import org.junit.Test;
import com.baeldung.algorithms.conversion.HexStringConverter;
public class ByteArrayConverterUnitTest {
private HexStringConverter hexStringConverter;
@Before
public void setup() {
hexStringConverter = new HexStringConverter();
}
@Test
public void shouldEncodeByteArrayToHexStringUsingBigIntegerToString() {
byte[] bytes = getSampleBytes();
String hexString = getSampleHexString();
if(hexString.charAt(0) == '0') {
hexString = hexString.substring(1);
}
String output = hexStringConverter.encodeUsingBigIntegerToString(bytes);
assertThat(output, IsEqualIgnoringCase.equalToIgnoringCase(hexString));
}
@Test
public void shouldEncodeByteArrayToHexStringUsingBigIntegerStringFormat() {
byte[] bytes = getSampleBytes();
String hexString = getSampleHexString();
String output = hexStringConverter.encodeUsingBigIntegerStringFormat(bytes);
assertThat(output, IsEqualIgnoringCase.equalToIgnoringCase(hexString));
}
@Test
public void shouldDecodeHexStringToByteArrayUsingBigInteger() {
byte[] bytes = getSampleBytes();
String hexString = getSampleHexString();
byte[] output = hexStringConverter.decodeUsingBigInteger(hexString);
assertArrayEquals(bytes, output);
}
@Test
public void shouldEncodeByteArrayToHexStringUsingCharacterConversion() {
byte[] bytes = getSampleBytes();
String hexString = getSampleHexString();
String output = hexStringConverter.encodeHexString(bytes);
assertThat(output, IsEqualIgnoringCase.equalToIgnoringCase(hexString));
}
@Test
public void shouldDecodeHexStringToByteArrayUsingCharacterConversion() {
byte[] bytes = getSampleBytes();
String hexString = getSampleHexString();
byte[] output = hexStringConverter.decodeHexString(hexString);
assertArrayEquals(bytes, output);
}
@Test(expected=IllegalArgumentException.class)
public void shouldDecodeHexToByteWithInvalidHexCharacter() {
hexStringConverter.hexToByte("fg");
}
@Test
public void shouldEncodeByteArrayToHexStringDataTypeConverter() {
byte[] bytes = getSampleBytes();
String hexString = getSampleHexString();
String output = hexStringConverter.encodeUsingDataTypeConverter(bytes);
assertThat(output, IsEqualIgnoringCase.equalToIgnoringCase(hexString));
}
@Test
public void shouldDecodeHexStringToByteArrayUsingDataTypeConverter() {
byte[] bytes = getSampleBytes();
String hexString = getSampleHexString();
byte[] output = hexStringConverter.decodeUsingDataTypeConverter(hexString);
assertArrayEquals(bytes, output);
}
@Test
public void shouldEncodeByteArrayToHexStringUsingGuava() {
byte[] bytes = getSampleBytes();
String hexString = getSampleHexString();
String output = hexStringConverter.encodeUsingGuava(bytes);
assertThat(output, IsEqualIgnoringCase.equalToIgnoringCase(hexString));
}
@Test
public void shouldDecodeHexStringToByteArrayUsingGuava() {
byte[] bytes = getSampleBytes();
String hexString = getSampleHexString();
byte[] output = hexStringConverter.decodeUsingGuava(hexString);
assertArrayEquals(bytes, output);
}
@Test
public void shouldEncodeByteArrayToHexStringUsingApacheCommons() throws DecoderException {
byte[] bytes = getSampleBytes();
String hexString = getSampleHexString();
String output = hexStringConverter.encodeUsingApacheCommons(bytes);
assertThat(output, IsEqualIgnoringCase.equalToIgnoringCase(hexString));
}
@Test
public void shouldDecodeHexStringToByteArrayUsingApacheCommons() throws DecoderException {
byte[] bytes = getSampleBytes();
String hexString = getSampleHexString();
byte[] output = hexStringConverter.decodeUsingApacheCommons(hexString);
assertArrayEquals(bytes, output);
}
private String getSampleHexString() {
return "0af50c0e2d10";
}
private byte[] getSampleBytes() {
return new byte[] { 10, -11, 12, 14, 45, 16 };
}
}