Add DigestUtils

Trinea · Trinea · commit 78e6634069d2 · 2014-03-24T20:06:40.000+08:00
diff --git a/src/cn/trinea/android/common/util/DigestUtils.java b/src/cn/trinea/android/common/util/DigestUtils.java
@@ -0,0 +1,55 @@
+package cn.trinea.android.common.util;
+
+import java.security.MessageDigest;
+
+/**
+ * DigestUtils
+ * 
+ * @author <a href="http://www.trinea.cn" target="_blank">Trinea</a> 2014-03-20
+ */
+public class DigestUtils {
+
+    /**
+     * Used to build output as Hex
+     */
+    private static final char[] DIGITS_LOWER = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd',
+            'e', 'f'                        };
+
+    /**
+     * encode By MD5
+     * 
+     * @param str
+     * @return String
+     */
+    public static String md5(String str) {
+        if (str == null) {
+            return null;
+        }
+        try {
+            MessageDigest messageDigest = MessageDigest.getInstance("MD5");
+            messageDigest.update(str.getBytes());
+            return new String(encodeHex(messageDigest.digest()));
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
+     * The returned array will be double the length of the passed array, as it takes two characters to represent any
+     * given byte.
+     * 
+     * @param data a byte[] to convert to Hex characters
+     * @return A char[] containing hexadecimal characters
+     */
+    protected static char[] encodeHex(final byte[] data) {
+        final int l = data.length;
+        final char[] out = new char[l << 1];
+        // two characters form the hex value.
+        for (int i = 0, j = 0; i < l; i++) {
+            out[j++] = DIGITS_LOWER[(0xF0 & data[i]) >>> 4];
+            out[j++] = DIGITS_LOWER[0x0F & data[i]];
+        }
+        return out;
+    }
+}
