working on string-templated based static pages

src/main/java/de/srsoftware/widerhall/Util.java

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+package de.srsoftware.widerhall;
+
+import de.srsoftware.examples.translations.App;
+import de.srsoftware.tools.translations.Translation;
+
+import java.net.URLEncoder;
+import java.nio.charset.StandardCharsets;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.regex.Pattern;
+import java.util.stream.Collectors;
+
+public class Util {
+
+    private static final MessageDigest SHA256 = getSha256();
+    private static final String EMAIL_PATTERN = "^[a-zA-Z0-9_!#$%&'*+/=?`{|}~^-]+(?:\\.[a-zA-Z0-9_!#$%&'*+/=?`{|}~^-]+)*@[a-zA-Z0-9-]+(?:\\.[a-zA-Z0-9-]+)*$";
+
+    public static String urlEncode(Map<String, Object> data) {
+        String params = data.entrySet()
+                .stream()
+                .map(entry -> encode(entry.getKey()) + "=" + encode(entry.getValue()))
+                .collect(Collectors.joining("&"));
+        return params;
+    }
+
+    private static String encode(Object value) {
+        return URLEncoder.encode(value.toString(), StandardCharsets.UTF_8);
+    }
+
+
+    public static MessageDigest getSha256() {
+        try {
+            return MessageDigest.getInstance("SHA-256");
+        } catch (NoSuchAlgorithmException e) {
+            e.printStackTrace();
+            return null;
+        }
+    }
+
+    public static String sha256(String s) {
+        byte[] bytes = SHA256.digest(s.getBytes(StandardCharsets.UTF_8));
+        return hex(bytes);
+    }
+
+    private static String hex(byte[] bytes) {
+        StringBuffer buf = new StringBuffer(bytes.length*2);
+        for (var byt : bytes) buf.append(hex(byt));
+        return buf.toString();
+    }
+
+    private static String hex(byte b){
+        return (b<16 ? "0" : "") + Integer.toHexString(b);
+    }
+
+    public static String t(String tx, Object ... fills){
+        return Translation.get(Application.class,tx,fills);
+    }
+
+    public static boolean isEmail(String email) {
+        return email.matches(EMAIL_PATTERN);
+    }
+}