Add JsonFactoryBuilder.configureForJackson2(), JsonFactoryBuilder builderWithJackson2Defaults()

src/main/java/tools/jackson/core/json/JsonFactory.java

@@ -183,14 +183,32 @@ public JsonFactoryBuilder rebuild() {
 
     /**
      * Main factory method to use for constructing {@link JsonFactory} instances with
-     * different configuration.
-     *
+     * different configuration. The builder returned uses default settings more closely
+     * matched the default configs used in Jackson 2.x versions.
+     * <p>
+     *     This method is still a work in progress and may not yet fully replicate the
+     *     default settings of Jackson 2.x.
+     * </p>
      * @return Builder instance to use
      */
     public static JsonFactoryBuilder builder() {
         return new JsonFactoryBuilder();
     }
 
+    /**
+     * Factory method to use for constructing {@link JsonFactory} instances with
+     * different configuration.
+     *
+     * @return Builder instance to use
+     */
+    public static JsonFactoryBuilder builderWithJackson2Defaults() {
+        return builder()
+                .disable(JsonWriteFeature.ESCAPE_FORWARD_SLASHES)
+                .disable(JsonWriteFeature.COMBINE_UNICODE_SURROGATES_IN_UTF8)
+                .disable(StreamReadFeature.USE_FAST_DOUBLE_PARSER)
+                .disable(StreamReadFeature.USE_FAST_BIG_NUMBER_PARSER);
+    }
+
     /**
      * Method for constructing a new {@link JsonFactory} that has
      * the same settings as this instance, but is otherwise

src/test/java/tools/jackson/core/unittest/json/JsonFactoryTest.java

@@ -345,6 +345,15 @@ public void testCanonicalizationDisabled() throws Exception {
         doCanonicalizationTest(false);
     }
 
+    @Test
+    public void testBuilderWithJackson2Defaults() {
+        JsonFactory factory = JsonFactory.builderWithJackson2Defaults().build();
+        assertFalse(factory.isEnabled(StreamReadFeature.USE_FAST_DOUBLE_PARSER));
+        assertFalse(factory.isEnabled(StreamReadFeature.USE_FAST_BIG_NUMBER_PARSER));
+        assertFalse(factory.isEnabled(JsonWriteFeature.ESCAPE_FORWARD_SLASHES));
+        assertFalse(factory.isEnabled(JsonWriteFeature.COMBINE_UNICODE_SURROGATES_IN_UTF8));
+    }
+
     // Configure the JsonFactory as expected, and verify across common shapes of input
     // to cover common JsonParser implementations.
     private void doCanonicalizationTest(boolean canonicalize) throws Exception {