Support mimetype detection on byte array

org.eclipse.scout.rt.platform.test/src/test/java/org/eclipse/scout/rt/platform/resource/MimeTypesTest.java

@@ -47,6 +47,22 @@ public void testVerifyMagic() {
     assertFalse(verifyMagic(BinaryResources.create().withContent(HexUtility.decode("ffaaaa")).withFilename("invalid.jpg").build()));
   }
 
+  @Test
+  public void findByMagicBytes() {
+    // jpg
+    assertTrue(MimeTypes.findByMagicBytes(HexUtility.decode("ffd8ff")).contains(MimeType.JPG));
+
+    // unknown mime-type
+    assertTrue(MimeTypes.findByMagicBytes(new byte[0]).isEmpty());
+    assertTrue(MimeTypes.findByMagicBytes(null).isEmpty());
+
+    // wav
+    assertTrue(MimeTypes.findByMagicBytes(HexUtility.decode("5249 4646 2e2e 2e2e 5741 5645")).contains(MimeType.WAV));
+
+    // pdf
+    assertTrue(MimeTypes.findByMagicBytes(HexUtility.decode("2550 4446")).contains(MimeType.PDF));
+  }
+
   @Test
   public void testMatches() throws IOException {
     assertFalse(MimeType.JAR.matches((Path) null));

org.eclipse.scout.rt.platform/src/main/java/org/eclipse/scout/rt/platform/resource/MimeTypes.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010, 2025 BSI Business Systems Integration AG
+ * Copyright (c) 2010, 2026 BSI Business Systems Integration AG
  *
  * This program and the accompanying materials are made
  * available under the terms of the Eclipse Public License 2.0
@@ -83,10 +83,17 @@ public static Collection<IMimeType> findByContentMagic(BinaryResource res) {
     if (res == null) {
       return Collections.emptyList();
     }
+    return findByMagicBytes(res.getContent());
+  }
+
+  public static Collection<IMimeType> findByMagicBytes(byte[] bytes) {
+    if (bytes == null) {
+      return Collections.emptyList();
+    }
     return EXT_TO_MIMETYPE
         .values()
         .stream()
-        .filter(t -> t.getMagic() != null && t.getMagic().matches(res))
+        .filter(t -> t.getMagic() != null && t.getMagic().matches(bytes))
         .collect(Collectors.toList());
   }
 
@@ -115,9 +122,6 @@ public static boolean verifyMagic(BinaryResource res) {
     Set<String> detectedMajorParts = findByContentMagic(res).stream()
         .map(IMimeType::getMajorPart)
         .collect(Collectors.toSet());
-    if (detectedMajorParts.isEmpty() || detectedMajorParts.contains(ext)) {
-      return true;
-    }
-    return false;
+    return (detectedMajorParts.isEmpty() || detectedMajorParts.contains(ext));
   }
 }