Implement #103, binary-data capability introspection

release-notes/VERSION

@@ -16,6 +16,8 @@ New minor version.
   current field name
  (reported by Sam R)
 #98: Improve handling of failures for `BigDecimal`, for "NaN" (and infinity)
+#103: Add `JsonFactory.canHandleBinaryNatively`, `JsonGenerator.canWriteBinaryNatively`
+ to let databind module detect level of support for binary data.
 - Improve `DefaultPrettyPrinter`, `Lf2SpacesIndenter` (from databind #276)
 - Add `JsonGenerator.canOmitFields()` method to support discovery of
   positional formats, needed for handling of filtering for CSV

src/main/java/com/fasterxml/jackson/core/JsonFactory.java

@@ -355,7 +355,23 @@ protected Object readResolve() {
     public boolean requiresPropertyOrdering() {
         return false;
     }
-
+
+    /**
+     * Introspection method that higher-level functionality may call
+     * to see whether underlying data format can read and write binary
+     * data natively; that is, embeded it as-is without using encodings
+     * such as Base64.
+     *<p>
+     * Default implementation returns <code>false</code> as JSON does not
+     * support native access: all binary content must use Base64 encoding.
+     * Most binary formats (like Smile and Avro) support native binary content.
+     * 
+     * @since 2.3
+     */
+    public boolean canHandleBinaryNatively(FormatSchema schema) {
+        return false;
+    }
+
     /*
     /**********************************************************
     /* Format detection functionality (since 1.8)

src/main/java/com/fasterxml/jackson/core/JsonGenerator.java

@@ -487,6 +487,20 @@ public boolean canWriteTypeId() {
         return false;
     }
 
+    /**
+     * Introspection method that may be called to see if the underlying
+     * data format supports "native" binary data; that is, an efficient
+     * output of binary content without encoding.
+     *<p>
+     * Default implementation returns false; overridden by data formats
+     * that do support native binary content.
+     * 
+     * @since 2.3
+     */
+    public boolean canWriteBinaryNatively() {
+        return false;
+    }
+
     /**
      * Introspection method to call to check whether it is ok to omit
      * writing of Object fields or not. Most formats do allow omission,

src/main/java/com/fasterxml/jackson/core/util/JsonGeneratorDelegate.java

@@ -77,6 +77,11 @@ public boolean canWriteObjectId() {
         return delegate.canWriteObjectId();
     }
 
+    @Override
+    public boolean canWriteBinaryNatively() {
+        return delegate.canWriteBinaryNatively();
+    }
+
     @Override
     public boolean canOmitFields() {
         return delegate.canOmitFields();