feat: 10진수를 Base62로 변환하는 컨버터 생성

src/main/java/com/programmers/urlshortener/common/converter/Base62Converter.java

@@ -0,0 +1,22 @@
+package com.programmers.urlshortener.common.converter;
+
+import lombok.AccessLevel;
+import lombok.NoArgsConstructor;
+
+@NoArgsConstructor(access = AccessLevel.PRIVATE)
+public class Base62Converter {
+
+    private static final String ALPHABET = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
+    private static final int BASE = ALPHABET.length();
+
+    public static String encode(int value) {
+        StringBuilder sb = new StringBuilder();
+
+        while (value != 0) {
+            sb.append(ALPHABET.charAt(value % BASE));
+            value /= BASE;
+        }
+
+        return sb.reverse().toString();
+    }
+}