#2 - Added test to test the cypto library

src/main/java/net/locusworks/crypto/utils/RandomString.java

@@ -0,0 +1,78 @@
+package net.locusworks.crypto.utils;
+
+import java.nio.charset.StandardCharsets;
+import java.security.SecureRandom;
+import java.util.Objects;
+import java.util.Random;
+
+public class RandomString {
+
+  public static final String LOWER = "abcdefghijklmnopqrstuvwxyz";
+  public static final String UPPER = LOWER.toUpperCase();
+  public static final String DIGITS = "0123456789";
+  
+  public static final String ALPHA_NUMERIC = LOWER + UPPER + DIGITS;
+  
+  private Random random;
+  
+  private char[] symbols;
+  private int length;
+  
+  private static RandomString instance;
+  
+  private RandomString(Integer length) {
+    this(length, new SecureRandom());
+  }
+  
+  private RandomString(Integer length, Random random) {
+    this(length, random, ALPHA_NUMERIC);
+  }
+  
+  private RandomString(Integer length, Random random, String symbols) {
+    if (length < 1) throw new IllegalArgumentException("Length has to be greater than 1");
+    if (symbols.length() < 2) throw new IllegalArgumentException("Symbols need to be greater than 2");
+    this.random = Objects.requireNonNull(random);
+    this.symbols = symbols.toCharArray();
+  }
+  
+  private synchronized final void setRandom(Random random) {
+    this.random = random;
+  }
+
+  private synchronized final void setLength(int length) {
+    this.length = length;
+  }
+
+  public String nextString() {
+    char[] buffer = new char[length];
+    for (int index = 0; index < buffer.length; index++) {
+     buffer[index] = symbols[random.nextInt(symbols.length)]; 
+    }
+    return new String(buffer);
+  }
+  
+  public static String getString(Integer length) {
+    if (instance == null) {
+      instance = new RandomString(length);
+    }
+    instance.setLength(length);
+    return instance.nextString();
+  }
+  
+  public static String getString(Integer length, Random random) {
+    if (instance == null) {
+      instance = new RandomString(length);
+    }
+    instance.setLength(length);
+    instance.setRandom(random);
+    return instance.nextString();
+  }
+  
+  public static byte[] getBytes(Integer length) {
+    return getString(length).getBytes(StandardCharsets.UTF_8);
+  }
+  
+  public static byte[] getBytes(Integer length, Random random) {
+    return getString(length, random).getBytes(StandardCharsets.UTF_8);
+  }
+}