com.fasterxml.jackson.databind.node.ArrayNode#addNull ( )源码实例Demo

/**
 * A shim into transformForBqSchema for translating tuples into objects and to
 * reconstruct additional properties.
 * @param jsonFieldName The name of the original JSON field.
 * @param fields A list of types for each element of the tuple.
 * @param tuple A list of objects that are mapped into a record.
 * @param additionalProperties A mutable map of elements that aren't captured in the schema.
 * @return A record object with anonymous struct naming.
 */
private ObjectNode processTupleField(String jsonFieldName, List<Field> fields, ArrayNode tuple,
    ObjectNode additionalProperties) {
  final ObjectNode m = Json.createObjectNode();
  for (int i = 0; i < tuple.size(); i++) {
    m.set(String.format("f%d_", i), tuple.get(i));
  }
  final ObjectNode props = additionalProperties == null ? null : Json.createObjectNode();
  transformForBqSchema(m, fields, props);
  if (!Json.isNullOrEmpty(props)) {
    final ArrayNode tupleAdditionalProperties = Json.createArrayNode();
    for (int i = 0; i < tuple.size(); i++) {
      tupleAdditionalProperties.addNull();
    }
    props.fields().forEachRemaining(e -> {
      int index = Integer.parseInt(e.getKey().substring(1, e.getKey().length() - 1));
      tupleAdditionalProperties.set(index, e.getValue());
    });
    additionalProperties.set(jsonFieldName, tupleAdditionalProperties);
  }
  return m;
}
 

@SuppressWarnings({"unchecked", "rawtypes"})
private <T> void internalSetCollection(String propertyName, Collection<T> collection, ArrayNode targetArray) {
    for (T childValue : collection) {
        if (childValue == null) {
            // Sets null.
            targetArray.addNull();
        } else if (childValue instanceof Collection) {
            // When T is also a Collection, use recursion.
            ArrayNode childArray = targetArray.addArray();
            this.internalSetCollection(propertyName, (Collection) childValue, childArray);
        } else if (childValue instanceof JsonNode) {
            targetArray.add((JsonNode) childValue);
        } else if (childValue instanceof JsonSerializable) {
            // JsonSerializable
            JsonSerializable castedValue = (JsonSerializable) childValue;
            castedValue.populatePropertyBag();
            targetArray.add(castedValue.propertyBag != null ? castedValue.propertyBag : this.getMapper().createObjectNode());
        } else {
            // POJO, JSONObject, Number (includes Int, Float, Double etc),
            // Boolean, and String.
            targetArray.add(this.getMapper().valueToTree(childValue));
        }
    }
}
 

/** Converts a {@link ReadableArray} into an Json {@link ArrayNode} */
static ArrayNode toJsonArray(ReadableArray readableArray) {
  JsonNodeFactory nodeFactory = JsonNodeFactory.instance;
  ArrayNode result = nodeFactory.arrayNode();
  for (int i = 0; i < readableArray.size(); i++) {
    ReadableType indexType = readableArray.getType(i);
    switch (indexType) {
      case Null:
        result.addNull();
        break;
      case Boolean:
        result.add(readableArray.getBoolean(i));
        break;
      case Number:
        result.add(readableArray.getDouble(i));
        break;
      case String:
        result.add(readableArray.getString(i));
        break;
      case Map:
        result.add(toJsonObject(readableArray.getMap(i)));
        break;
      case Array:
        result.add(toJsonArray(readableArray.getArray(i)));
        break;
      default:
        Log.e(TAG, "Could not convert object at index " + i + ".");
    }
  }
  return result;
}
 

/**
 * Add a value to a column.
 *
 * @param row The JSON array representing the column.
 * @param type The type of the value.
 * @param value The (possibly null) value.
 */
public static void addData(final ArrayNode row, final String type, final String value) {
    switch (type) {
        case BooleanAttributeDescription.ATTRIBUTE_NAME:
        case BooleanObjectAttributeDescription.ATTRIBUTE_NAME:
            // A DataFrame will parse [True, False, None] to [1.0, 0.0, Nan],
            // so implicitly convert null to False so the result is all booleans.
            row.add(Boolean.parseBoolean(value));
            break;
        case ColorAttributeDescription.ATTRIBUTE_NAME:
            if (value == null) {
                row.addNull();
            } else {
                final ArrayNode rgb = row.addArray();
                final ConstellationColor cv = ConstellationColor.getColorValue(value);
                rgb.add(cv.getRed());
                rgb.add(cv.getGreen());
                rgb.add(cv.getBlue());
                rgb.add(cv.getAlpha());
            }
            break;
        case ZonedDateTimeAttributeDescription.ATTRIBUTE_NAME:
            // A DataFrame will parse null as NaT.
            if (value == null) {
                row.addNull();
            } else {
                // Remove the trailing tz name if present.
                final int ix = value.lastIndexOf(" [");
                row.add(ix == -1 ? value : value.substring(0, ix));
            }
            break;
        case FloatAttributeDescription.ATTRIBUTE_NAME:
        case FloatObjectAttributeDescription.ATTRIBUTE_NAME:
            // A DataFrame will parse null as NaN.
            if (value == null) {
                row.addNull();
            } else {
                row.add(Float.parseFloat(value));
            }
            break;
        case IntegerAttributeDescription.ATTRIBUTE_NAME:
        case IntegerObjectAttributeDescription.ATTRIBUTE_NAME:
            // A DataFrame will parse null as NaN, but the column will be
            // converted to a float column.
            if (value == null) {
                row.addNull();
            } else {
                row.add(Integer.parseInt(value));
            }
            break;
        default:
            // Everything else we leave as a string; nulls are fine.
            row.add(value);
            break;
    }
}