New decrypt activity design (WIP), saner UTF8 decoding (replacing non-decodable characters)

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/util/Utf8Util.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2014 Dominik Schürmann <dominik@dominikschuermann.de>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.sufficientlysecure.keychain.util;
+
+import org.sufficientlysecure.keychain.Constants;
+
+import java.nio.ByteBuffer;
+import java.nio.charset.CharacterCodingException;
+import java.nio.charset.Charset;
+import java.nio.charset.CharsetDecoder;
+import java.nio.charset.CodingErrorAction;
+
+public class Utf8Util {
+
+    public static boolean isValidUTF8(byte[] input) {
+        CharsetDecoder cs = Charset.forName("UTF-8").newDecoder();
+
+        try {
+            cs.decode(ByteBuffer.wrap(input));
+            return true;
+        } catch (CharacterCodingException e) {
+            return false;
+        }
+    }
+
+    public static String fromUTF8ByteArrayReplaceBadEncoding(byte[] input) {
+        final CharsetDecoder charsetDecoder = Charset.forName("UTF-8").newDecoder();
+        charsetDecoder.onMalformedInput(CodingErrorAction.REPLACE);
+        charsetDecoder.onUnmappableCharacter(CodingErrorAction.REPLACE);
+
+        try {
+            return charsetDecoder.decode(ByteBuffer.wrap(input)).toString();
+        } catch (CharacterCodingException e) {
+            Log.e(Constants.TAG, "Decoding failed!", e);
+            return charsetDecoder.replacement();
+        }
+    }
+}