Case Study: Hashing with MD5

src/CodingCaseStudy/Hash_MD5/Case01_Hash_MD5.java

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+package CodingCaseStudy.Hash_MD5;
+
+import java.security.NoSuchAlgorithmException;
+
+import static CodingCaseStudy.Hash_MD5.Hash_MD5.hashMD5;
+
+public class Case01_Hash_MD5 {
+ public static void main(String[] args) throws NoSuchAlgorithmException {
+ String password = "ILoveJava";
+ String resultHashMD5 = hashMD5(password.getBytes());
+ String resultHashMD5Kotlin = Hash_MD5_Kotlin.hashMD5Kotlin(password.getBytes());
+
+ System.out.println(resultHashMD5); // Using Java
+ System.out.println(resultHashMD5Kotlin); // Using Kotlin
+
+ Hash_MD5_Kotlin hashMD5 = new Hash_MD5_Kotlin();
+ System.out.println(hashMD5.toMD5(password)); // Version Two Kotlin
+
+ System.out.println(resultHashMD5.toLowerCase()); // Using Java
+ System.out.println(resultHashMD5Kotlin.toLowerCase()); // Using Kotlin
+ }
+}

src/CodingCaseStudy/Hash_MD5/Case02_Hash_MD5.java

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+package CodingCaseStudy.Hash_MD5;
+
+import java.security.NoSuchAlgorithmException;
+
+import static CodingCaseStudy.Hash_MD5.Hash_MD5.hashMD5;
+
+public class Case02_Hash_MD5 {
+ public static void main(String[] args) throws NoSuchAlgorithmException {
+ StringBuilder stringBuilder = new StringBuilder();
+ String strTrace = String.format("%06d", 1);
+ String timestamp = String.valueOf(System.currentTimeMillis());
+ String merchantOrderId = timestamp + strTrace;
+
+ stringBuilder.append("D6368");
+ stringBuilder.append(merchantOrderId);
+ stringBuilder.append("10000");
+ stringBuilder.append("1ee1f3cfcbccfd22b37b808b89e3ee6e");
+
+ String sbString = String.valueOf(stringBuilder);
+ System.out.println("String Builder: \n" + sbString);
+
+ String resultHashMD5 = hashMD5(sbString.getBytes());
+
+ System.out.print(resultHashMD5.toLowerCase()); // Using Java
+ }
+}

src/CodingCaseStudy/Hash_MD5/Hash_MD5.java

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+package CodingCaseStudy.Hash_MD5;
+
+import javax.xml.bind.DatatypeConverter;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+
+public class Hash_MD5 {
+ public static String hashMD5(byte[] bytes) throws NoSuchAlgorithmException {
+ MessageDigest md = MessageDigest.getInstance("MD5");
+ md.update(bytes);
+ byte[] digest = md.digest();
+ return DatatypeConverter.printHexBinary(digest);
+ }
+}

src/CodingCaseStudy/Hash_MD5/Hash_MD5_Kotlin.kt

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+package CodingCaseStudy.Hash_MD5
+
+import java.security.MessageDigest
+import javax.xml.bind.DatatypeConverter
+
+class Hash_MD5_Kotlin {
+ companion object {
+ @JvmStatic
+ fun hashMD5Kotlin(bytes: ByteArray): String {
+ val md = MessageDigest.getInstance("MD5")
+ md.update(bytes)
+ val digest = md.digest()
+ return DatatypeConverter.printHexBinary(digest)
+ }
+ }
+ fun toMD5(txt: String): String {
+ val bytes = MessageDigest.getInstance("MD5").digest(txt.toByteArray())
+ return bytes.toHex()
+ }
+ private fun ByteArray.toHex(): String {
+ return joinToString("") { "%02x".format(it) }
+ }
+}