[Java] Support binary vardata in json printer (#914)

Author: vdaniloff

sbe-tool/src/main/java/uk/co/real_logic/sbe/json/JsonTokenListener.java

@@ -16,6 +16,7 @@
 package uk.co.real_logic.sbe.json;
 
 import org.agrona.DirectBuffer;
+import org.agrona.PrintBufferUtil;
 import uk.co.real_logic.sbe.PrimitiveValue;
 import uk.co.real_logic.sbe.ir.Encoding;
 import uk.co.real_logic.sbe.ir.Token;
@@ -230,7 +231,10 @@ public void onVarData(
 
             final byte[] tempBuffer = new byte[length];
             buffer.getBytes(bufferIndex, tempBuffer, 0, length);
-            final String str = new String(tempBuffer, 0, length, typeToken.encoding().characterEncoding());
+
+            final String charsetName = typeToken.encoding().characterEncoding();
+            final String str = charsetName != null ? new String(tempBuffer, 0, length, charsetName) :
+                PrintBufferUtil.hexDump(tempBuffer);
 
             escape(str);
 

sbe-tool/src/test/java/uk/co/real_logic/sbe/json/JsonPrinterTest.java

@@ -15,6 +15,9 @@
  */
 package uk.co.real_logic.sbe.json;
 
+import baseline.CredentialsEncoder;
+import baseline.MessageHeaderEncoder;
+import org.agrona.concurrent.UnsafeBuffer;
 import org.junit.jupiter.api.Test;
 import uk.co.real_logic.sbe.EncodedCarTestBase;
 import uk.co.real_logic.sbe.ir.Ir;
@@ -125,6 +128,33 @@ void exampleMessagePrintedAsJson() throws Exception
             result);
     }
 
+    @Test
+    public void exampleVarData() throws Exception
+    {
+        final ByteBuffer encodedSchemaBuffer = ByteBuffer.allocate(SCHEMA_BUFFER_CAPACITY);
+        encodeSchema(encodedSchemaBuffer);
+
+        final ByteBuffer encodedMsgBuffer = ByteBuffer.allocate(MSG_BUFFER_CAPACITY);
+        final UnsafeBuffer buffer = new UnsafeBuffer(encodedMsgBuffer);
+        final CredentialsEncoder encoder = new CredentialsEncoder();
+        encoder.wrapAndApplyHeader(buffer, 0, new MessageHeaderEncoder());
+        encoder.login("example");
+        encoder.putEncryptedPassword(new byte[] {11, 0, 64, 97}, 0, 4);
+        encodedMsgBuffer.position(encoder.encodedLength());
+
+        encodedSchemaBuffer.flip();
+        final Ir ir = decodeIr(encodedSchemaBuffer);
+
+        final JsonPrinter printer = new JsonPrinter(ir);
+        final String result = printer.print(encodedMsgBuffer);
+        assertEquals(
+            "{\n" +
+            "    \"login\": \"example\",\n" +
+            "    \"encryptedPassword\": \"0b004061\"\n" +
+            "}",
+            result);
+    }
+
     private static void encodeSchema(final ByteBuffer buffer) throws Exception
     {
         final Path path = Paths.get("src/test/resources/json-printer-test-schema.xml");

sbe-tool/src/test/resources/json-printer-test-schema.xml

@@ -23,6 +23,10 @@
         </composite>
         <type name="uuid_t" primitiveType="int64" length="2"/>
         <type name="cupHolderCount_t" primitiveType="uint8"/>
+        <composite name="varDataEncoding">
+            <type name="length" primitiveType="uint32" maxValue="1073741824"/>
+            <type name="varData" primitiveType="uint8" length="0"/>
+        </composite>
     </types>
     <types>
         <type name="ModelYear" primitiveType="uint16"/>
@@ -77,4 +81,11 @@
         <data name="model" id="18" type="varStringEncoding"/>
         <data name="activationCode" id="19" type="varStringEncoding"/>
     </sbe:message>
+
+    <sbe:message name="Credentials" id="2">
+        <data name="login" id="1" type="varStringEncoding"/>
+        <!-- variable length encoding with embedded length in composite -->
+        <data id="2" name="encryptedPassword" type="varDataEncoding"/>
+    </sbe:message>
+
 </sbe:messageSchema>