Add a nicer util method for decoding any multibase encoded multihash

Author: ianopolous

src/main/java/io/ipfs/multihash/Multihash.java

@@ -218,6 +218,18 @@ public static Multihash deserialize(byte[] raw) throws IOException {
         return deserialize(new ByteArrayInputStream(raw));
     }
 
+    /**
+     *
+     * @param encoded A multibase encoded serialization of a Multihash
+     * @return
+     * @throws IOException
+     */
+    public static Multihash decode(String encoded) throws IOException {
+        if (encoded.length() == 46 && encoded.startsWith("Qm"))
+            return deserialize(Base58.decode(encoded));
+        return deserialize(Multibase.decode(encoded));
+    }
+
     @Override
     public String toString() {
         return toBase58();

src/test/java/io/ipfs/multihash/MultihashTest.java

@@ -1,8 +1,9 @@
 package io.ipfs.multihash;
 
-import io.ipfs.multibase.Base58;
+import io.ipfs.multibase.*;
 import org.junit.Test;
 
+import java.io.*;
 import java.security.MessageDigest;
 import java.util.Arrays;
 import java.util.List;
@@ -22,6 +23,22 @@ public void base58Test() {
         }
     }
 
+    @Test
+    public void decodeTest() throws IOException {
+        List<String> base58 = Arrays.asList(
+                "QmPZ9gcCEpqKTo6aq61g2nXGUhM4iCL3ewB6LDXZCtioEB",
+                "QmatmE9msSfkKxoffpHwNLNKgwZG8eT9Bud6YoPab52vpy"
+        );
+        List<String> base36 = Arrays.asList(
+                "kmue2y4illvr0m3lt8x6z8iwghtxlzdmkjh957p5rr5cdr9243ugc",
+                "kmuia3qyasz2z5cnz848bag5n5wfc7gzi35cz2npamtmkyifd5anu");
+        for (int i=0; i < base58.size(); i++) {
+            Multihash b58 = Multihash.decode(base58.get(i));
+            Multihash b36 = Multihash.decode(base36.get(i));
+            assertEquals(b58, b36);
+        }
+    }
+
     @Test
     public void multihashTest() {
         Object[][] examples = new Object[][]{