我一直在按照this sample
来实现这个自定义JSON编写器我覆盖了WriteValue
方法,以便不打印json的值,而是打印Type.ToString()
并隐藏项目的实际值。
我遇到了这种方法的问题:
private void WriteValueElement(string elementName, JTokenType type)
{
_writer.WriteStartElement(elementName);
_writer.WriteAttributeString("type", type.ToString());
}
尤其是这句话_writer.WriteStartElement(elementName);
我无法弄清楚这个WriteStartElement的位置。此方法签名不存在于baseClass中,但在样本中也没有任何内容
答案 0 :(得分:2)
如果要通过继承JsonTextWriter
或JsonWriter
来执行此操作,则需要覆盖所有WriteValue
方法并重新映射正在写入的值。这个名称有很多种方法,因为Newtonsoft理论上可以在以后的版本中添加新方法(例如BigNumber
),这可能会成为维护麻烦。
更简单的解决方案可能是serialize to JToken
然后重新映射这些值:
public static class JsonExtensions
{
public static IList<JToken> ChildrenTokenList(this JContainer container)
{
return container;
}
public static IEnumerable<JToken> DescendantsAndSelf(this JToken node)
{
// Small wrapper adding this method to all JToken types.
if (node == null)
return Enumerable.Empty<JToken>();
var container = node as JContainer;
if (container != null)
return container.DescendantsAndSelf();
else
return new[] { node };
}
public static JToken MapValues(this JToken root, Func<JValue, JValue> map)
{
if (map == null || root == null)
throw new ArgumentNullException();
if (root is JValue)
return map((JValue)root);
else
{
root = root.DeepClone();
foreach (var container in root.DescendantsAndSelf().OfType<JContainer>())
{
var children = container.ChildrenTokenList();
for (int i = 0, n = children.Count; i < n; i++)
if (children[i] is JValue)
children[i] = map((JValue)children[i]);
}
return root;
}
}
public static JToken MapValuesToValueTypes(this JToken root)
{
return root.MapValues(v => (v.Type == JTokenType.Null ? (JValue)null : (JValue)v.Type.ToString()));
}
}
如果你坚持继承编写器,原型实现将如下所示:
public class ValueTypeJsonWriter : JsonTextWriter
{
public ValueTypeJsonWriter(TextWriter textWriter)
: base(textWriter)
{
}
private void WriteValueType(object value)
{
if (value == null)
base.WriteNull();
else
{
var token = JToken.FromObject(value);
base.WriteValue(token.Type.ToString());
}
}
public override void WriteValue(object value)
{
WriteValueType(value);
}
public override void WriteValue(bool value)
{
WriteValueType(value);
}
public override void WriteValue(bool? value)
{
WriteValueType(value);
}
public override void WriteValue(byte value)
{
WriteValueType(value);
}
public override void WriteValue(byte? value)
{
WriteValueType(value);
}
public override void WriteValue(byte[] value)
{
WriteValueType(value);
}
public override void WriteValue(char value)
{
WriteValueType(value);
}
public override void WriteValue(char? value)
{
WriteValueType(value);
}
public override void WriteValue(DateTime value)
{
WriteValueType(value);
}
public override void WriteValue(DateTime? value)
{
WriteValueType(value);
}
public override void WriteValue(DateTimeOffset value)
{
WriteValueType(value);
}
public override void WriteValue(DateTimeOffset? value)
{
WriteValueType(value);
}
public override void WriteValue(decimal value)
{
WriteValueType(value);
}
public override void WriteValue(decimal? value)
{
WriteValueType(value);
}
public override void WriteValue(double value)
{
WriteValueType(value);
}
public override void WriteValue(double? value)
{
WriteValueType(value);
}
public override void WriteValue(float value)
{
WriteValueType(value);
}
public override void WriteValue(float? value)
{
WriteValueType(value);
}
public override void WriteValue(Guid value)
{
WriteValueType(value);
}
public override void WriteValue(Guid? value)
{
WriteValueType(value);
}
public override void WriteValue(int value)
{
WriteValueType(value);
}
public override void WriteValue(int? value)
{
WriteValueType(value);
}
public override void WriteValue(long value)
{
WriteValueType(value);
}
public override void WriteValue(long? value)
{
WriteValueType(value);
}
public override void WriteValue(sbyte value)
{
WriteValueType(value);
}
public override void WriteValue(sbyte? value)
{
WriteValueType(value);
}
public override void WriteValue(short value)
{
WriteValueType(value);
}
public override void WriteValue(short? value)
{
WriteValueType(value);
}
public override void WriteValue(string value)
{
WriteValueType(value);
}
public override void WriteValue(TimeSpan value)
{
WriteValueType(value);
}
public override void WriteValue(TimeSpan? value)
{
WriteValueType(value);
}
public override void WriteValue(uint value)
{
WriteValueType(value);
}
public override void WriteValue(uint? value)
{
WriteValueType(value);
}
public override void WriteValue(ulong value)
{
WriteValueType(value);
}
public override void WriteValue(ulong? value)
{
WriteValueType(value);
}
public override void WriteValue(Uri value)
{
WriteValueType(value);
}
public override void WriteValue(ushort value)
{
WriteValueType(value);
}
public override void WriteValue(ushort? value)
{
WriteValueType(value);
}
}
原型fiddle。