com.fasterxml.jackson.databind.node.NullNode#instance ( )源码实例Demo

public JsonNode apply(Scope scope, JsonNode input) {
  JsonNode array = valueExpr.apply(scope, input);
  if (array.isNull())
    return NullNode.instance;
  else if (array.isObject())
    array = NodeUtils.convertObjectToArray(array);
  else if (!array.isArray())
    throw new JsltException("For loop can't iterate over " + array, location);

  ArrayNode result = NodeUtils.mapper.createArrayNode();
  for (int ix = 0; ix < array.size(); ix++) {
    JsonNode value = array.get(ix);

    // must evaluate lets over again for each value because of context
    if (lets.length > 0)
      NodeUtils.evalLets(scope, value, lets);

    if (ifExpr == null || NodeUtils.isTrue(ifExpr.apply(scope, value)))
      result.add(loopExpr.apply(scope, value));
  }
  return result;
}
 

public JsonNode apply(Scope scope, JsonNode input) {
  // Jackson 2.9.2 can parse to Java null. See unit test
  // QueryTest.testNullInput. so we have to handle that
  if (input == null)
    input = NullNode.instance;

  // evaluate lets in global modules
  if (fileModules != null) {
    for (int ix = 0; ix < fileModules.length; ix++)
      fileModules[ix].evaluateLetsOnly(scope, input);
  }

  // evaluate own lets
  NodeUtils.evalLets(scope, input, lets);

  return actual.apply(scope, input);
}
 

public JsonNode apply(Scope scope, JsonNode input) {
  JsonNode[] params = new JsonNode[arguments.length];
  for (int ix = 0; ix < params.length; ix++)
    params[ix] = arguments[ix].apply(scope, input);

  if (declared != null)
    return declared.call(scope, input, params);
  else {
    JsonNode value = function.call(input, params);

    // if the user-implemented function returns Java null, silently
    // turn it into a JSON null. (the alternative is to throw an
    // exception.)
    if (value == null)
      value = NullNode.instance;

    return value;
  }
}
 

public JsonNode call(JsonNode input, JsonNode[] arguments) {
  JsonNode number = arguments[0];
  if (number.isNull())
    return NullNode.instance;
  else if (!number.isNumber())
    throw new JsltException("round() cannot round a non-number: " + number);

  return new LongNode(Math.round(number.doubleValue()));
}
 

public JsonNode call(JsonNode input, JsonNode[] arguments) {
  JsonNode number = arguments[0];
  if (number.isNull())
    return NullNode.instance;
  else if (!number.isNumber())
    throw new JsltException("ceiling() cannot round a non-number: " + number);

  return new LongNode((long) Math.ceil(number.doubleValue()));
}
 

public JsonNode call(JsonNode input, JsonNode[] arguments) {
  JsonNode node = arguments[0];
  if (node.isNull())
    return NullNode.instance;
  try {
    // https://stackoverflow.com/a/18993481/90580
    final Object obj = mapper.treeToValue(node, Object.class);
    String jsonString = writer.writeValueAsString(obj);
    return new IntNode(jsonString.hashCode());
  } catch (JsonProcessingException e) {
    throw new JsltException("hash-int: can't process json" + e);
  }
}
 

public JsonNode call(JsonNode input, JsonNode[] arguments) {
  String string = NodeUtils.toString(arguments[0], true);
  if (string == null)
    return NullNode.instance;

  String regexp = NodeUtils.toString(arguments[1], false);
  String sep = NodeUtils.toString(arguments[2], false);

  Pattern p = getRegexp(regexp);
  Matcher m = p.matcher(string);
  char[] buf = new char[string.length() * Math.max(sep.length(), 1)];
  int pos = 0; // next untouched character in input
  int bufix = 0; // next unwritten character in buf

  while (m.find(pos)) {
    // we found another match, and now matcher state has been updated
    if (m.start() == m.end())
      throw new JsltException("Regexp " + regexp + " in replace() matched empty string in '" + arguments[0] + "'");

    // if there was text between pos and start of match, copy to output
    if (pos < m.start())
      bufix = copy(string, buf, bufix, pos, m.start());

    // copy sep to output (corresponds with the match)
    bufix = copy(sep, buf, bufix, 0, sep.length());

    // step over match
    pos = m.end();
  }

  if (pos == 0 && arguments[0].isTextual())
    // there were matches, so the string hasn't changed
    return arguments[0];
  else if (pos < string.length())
    // there was text remaining after the end of the last match. must copy
    bufix = copy(string, buf, bufix, pos, string.length());

  return new TextNode(new String(buf, 0, bufix));
}
 

public JsonNode call(JsonNode input, JsonNode[] arguments) {
  String string = NodeUtils.toString(arguments[0], true);
  if (string == null)
    return NullNode.instance;

  return new TextNode(string.trim());
}
 

public JsonNode call(JsonNode input, JsonNode[] arguments) {
  ArrayNode array = NodeUtils.toArray(arguments[0], true);
  if (array == null)
    return NullNode.instance;

  String sep = NodeUtils.toString(arguments[1], false);

  StringBuilder buf = new StringBuilder();
  for (int ix = 0; ix < array.size(); ix++) {
    if (ix > 0)
      buf.append(sep);
    buf.append(NodeUtils.toString(array.get(ix), false));
  }
  return new TextNode(buf.toString());
}
 

public JsonNode call(JsonNode input, JsonNode[] arguments) {
  JsonNode number = NodeUtils.number(arguments[0], null);
  if (number == null || number.isNull())
    return NullNode.instance;

  double timestamp = number.asDouble();

  String formatstr = NodeUtils.toString(arguments[1], false);

  TimeZone zone = new SimpleTimeZone(0, "UTC");
  if (arguments.length == 3) {
    String zonename = NodeUtils.toString(arguments[2], false);
    if (!zonenames.contains(zonename))
      throw new JsltException("format-time: Unknown timezone " + zonename);
    zone = TimeZone.getTimeZone(zonename);
  }

  // the performance of this could be better, but it's not so easy
  // to fix that when SimpleDateFormat isn't thread-safe, so we
  // can't safely share it between threads

  try {
    SimpleDateFormat format = new SimpleDateFormat(formatstr);
    format.setTimeZone(zone);
    String formatted = format.format(Math.round(timestamp * 1000));
    return new TextNode(formatted);
  } catch (IllegalArgumentException e) {
    // thrown if format is bad
    throw new JsltException("format-time: Couldn't parse format '" + formatstr + "': " + e.getMessage());
  }
}
 

public JsonNode call(JsonNode input, JsonNode[] arguments) {
  if (arguments[0].isNull() || arguments[1].isNull())
    return NullNode.instance;
  else if (ComparisonOperator.compare(arguments[0], arguments[1], null) > 0)
    return arguments[0];
  else
    return arguments[1];
}
 

public JsonNode call(JsonNode input, JsonNode[] arguments) {
  if (arguments[0].isNull())
    return NullNode.instance;

  String urlString = arguments[0].asText();

  try {
    URL aURL = new URL(arguments[0].asText());
    final ObjectNode objectNode = NodeUtils.mapper.createObjectNode();
    if (aURL.getHost() != null && !aURL.getHost().isEmpty())
      objectNode.put("host", aURL.getHost());
    if (aURL.getPort() != -1)
      objectNode.put("port", aURL.getPort());
    if (!aURL.getPath().isEmpty())
      objectNode.put("path", aURL.getPath());
    if (aURL.getProtocol() != null && !aURL.getProtocol().isEmpty())
      objectNode.put("scheme", aURL.getProtocol());
    if (aURL.getQuery() != null && !aURL.getQuery().isEmpty()) {
      objectNode.put("query", aURL.getQuery());
      final ObjectNode queryParamsNode = NodeUtils.mapper.createObjectNode();
      objectNode.set("parameters", queryParamsNode);
      final String[] pairs = aURL.getQuery().split("&");
      for (String pair : pairs) {
        final int idx = pair.indexOf("=");
        final String key = idx > 0 ? URLDecoder.decode(pair.substring(0, idx), "UTF-8") : pair;
        if (!queryParamsNode.has(key)) queryParamsNode.set(key, NodeUtils.mapper.createArrayNode());
        final String value = idx > 0 && pair.length() > idx + 1 ? URLDecoder.decode(pair.substring(idx + 1), "UTF-8") : null;
        final ArrayNode valuesNode = (ArrayNode) queryParamsNode.get(key);
        valuesNode.add(value);
      }
    }
    if(aURL.getRef() != null)
      objectNode.put("fragment", aURL.getRef());
    if(aURL.getUserInfo() != null && !aURL.getUserInfo().isEmpty())
      objectNode.put("userinfo", aURL.getUserInfo());
    return objectNode;
  } catch (MalformedURLException | UnsupportedEncodingException e) {
    throw new JsltException("Can't parse " + urlString, e);
  }
}
 

public JsonNode apply(Scope scope, JsonNode input) {
  // if there is no key we just return the input
  if (key == null)
    return input;

  // if we have a parent, get the input from the parent (preceding expr)
  if (parent != null)
    input = parent.apply(scope, input);

  // okay, do the keying
  JsonNode value = input.get(key);
  if (value == null)
    value = NullNode.instance;
  return value;
}
 

public JsonNode apply(Scope scope, JsonNode input) {
  if (NodeUtils.isTrue(test.apply(scope, input))) {
    NodeUtils.evalLets(scope, input, thenlets);
    return then.apply(scope, input);
  }

  // test was false, so return null or else
  if (orelse != null) {
    NodeUtils.evalLets(scope, input, elselets);
    return orelse.apply(scope, input);
  } else
    return NullNode.instance;
}
 

public JsonNode convert(Object node) {
  if (node == null)
    return NullNode.instance;
  else if ((Boolean) node)
    return BooleanNode.TRUE;
  else
    return BooleanNode.FALSE;
}
 

public JsonNode convert(Object node) {
  if (node == null)
    return NullNode.instance;
  else
    return new LongNode((Long) node);
}
 

public JsonNode convert(Object node) {
  if (node == null)
    return NullNode.instance;
  else
    return new IntNode((Integer) node);
}
 

public JsonNode convert(Object node) {
  if (node == null)
    return NullNode.instance;
  else
    return new FloatNode((Float) node);
}
 

public JsonNode convert(Object node) {
  if (node == null)
    return NullNode.instance;
  else
    return new TextNode((String) node);
}
 

public JsonNode convert(Object node) {
  if (node == null)
    return NullNode.instance;
  else
    return new DoubleNode((Double) node);
}