Init

src/main/java/de/w665/testing/service/TokenService.java

@@ -0,0 +1,35 @@
+package de.w665.testing.service;
+
+import org.springframework.stereotype.Service;
+
+import java.security.SecureRandom;
+import java.util.Base64;
+import java.util.Map;
+import java.util.Optional;
+import java.util.concurrent.ConcurrentHashMap;
+
+@Service
+public class TokenService {
+    private final Map<String, String> tokenToUser = new ConcurrentHashMap<>();
+    private final SecureRandom random = new SecureRandom();
+
+    public String createTokenForUsername(String username) {
+        String token = generateToken();
+        tokenToUser.put(token, username);
+        return token;
+    }
+
+    public Optional<String> resolveUsername(String token) {
+        return Optional.ofNullable(tokenToUser.get(token));
+    }
+
+    public void invalidate(String token) {
+        tokenToUser.remove(token);
+    }
+
+    private String generateToken() {
+        byte[] bytes = new byte[32];
+        random.nextBytes(bytes);
+        return Base64.getUrlEncoder().withoutPadding().encodeToString(bytes);
+    }
+}