1 files changed, 46 insertions, 0 deletions
diff --git a/java/src/org/kelar/inputmethod/dictionarypack/MD5Calculator.java b/java/src/org/kelar/inputmethod/dictionarypack/MD5Calculator.java
new file mode 100644
index 000000000..80d81c090
--- /dev/null
+++ b/java/src/org/kelar/inputmethod/dictionarypack/MD5Calculator.java
@@ -0,0 +1,46 @@
+/**
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package org.kelar.inputmethod.dictionarypack;
+
+import java.io.InputStream;
+import java.io.IOException;
+import java.security.MessageDigest;
+
+public final class MD5Calculator {
+    private MD5Calculator() {} // This helper class is not instantiable
+
+    public static String checksum(final InputStream in) throws IOException {
+        // This code from the Android documentation for MessageDigest. Nearly verbatim.
+        MessageDigest digester;
+        try {
+            digester = MessageDigest.getInstance("MD5");
+        } catch (java.security.NoSuchAlgorithmException e) {
+            return null; // Platform does not support MD5 : can't check, so return null
+        }
+        final byte[] bytes = new byte[8192];
+        int byteCount;
+        while ((byteCount = in.read(bytes)) > 0) {
+            digester.update(bytes, 0, byteCount);
+        }
+        final byte[] digest = digester.digest();
+        final StringBuilder s = new StringBuilder();
+        for (int i = 0; i < digest.length; ++i) {
+            s.append(String.format("%1$02x", digest[i]));
+        }
+        return s.toString();
+    }
+}