JSON值无法转换为System.Byte[]

Question

在处理字节数组时，我试图反序列化以下JSON时遇到以下异常，怎么了？

public class Program
{
public static void Main()
{
var root = JsonSerializer.Deserialize<JsonRoot>(@"{ ""ByteArray"": [1] } ");
}
public class JsonRoot
{
public byte[] ByteArray {get;set;}  
}
}

Unhandled exception. System.Text.Json.JsonException: The JSON value could not be converted to System.Byte[]. Path: $.ByteArray | LineNumber: 0 | BytePositionInLine: 16.
---> System.InvalidOperationException: Cannot get the value of a token type 'StartArray' as a string.
at System.Text.Json.Utf8JsonReader.TryGetBytesFromBase64(Byte[]& value)
at System.Text.Json.Utf8JsonReader.GetBytesFromBase64()
at System.Text.Json.Serialization.Converters.JsonConverterByteArray.Read(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options)
at System.Text.Json.JsonPropertyInfoNotNullable`4.OnRead(ReadStack& state, Utf8JsonReader& reader)
at System.Text.Json.JsonPropertyInfo.Read(JsonTokenType tokenType, ReadStack& state, Utf8JsonReader& reader)
at System.Text.Json.JsonSerializer.ReadCore(JsonSerializerOptions options, Utf8JsonReader& reader, ReadStack& readStack)
--- End of inner exception stack trace ---
at System.Text.Json.ThrowHelper.ReThrowWithPath(ReadStack& readStack, Utf8JsonReader& reader, Exception ex)
at System.Text.Json.JsonSerializer.ReadCore(JsonSerializerOptions options, Utf8JsonReader& reader, ReadStack& readStack)
at System.Text.Json.JsonSerializer.ReadCore(Type returnType, JsonSerializerOptions options, Utf8JsonReader& reader)
at System.Text.Json.JsonSerializer.Deserialize(String json, Type returnType, JsonSerializerOptions options)
at System.Text.Json.JsonSerializer.Deserialize[TValue](String json, JsonSerializerOptions options)
at Program.Main()
Command terminated by signal 6

Answer 1

使用Sytem.Text.Json，字节数组(byte[](将被序列化为base64字符串。他们表示不会在github问题中添加对byte[]序列化为数字数组的支持。

这里有一个自定义转换器，应该让你开始。也许你可以稍微优化一下读数，但这种方法对性能的影响应该不会太差。您可能想要添加null和错误处理，但您已经明白了。

要应用自定义转换器，您必须将它们添加到JsonSerializerOptions中。请参阅此文档页。

public class ByteArrayConverter : JsonConverter<byte[]>
{
public override byte[] Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
{
short[] sByteArray = JsonSerializer.Deserialize<short[]>(ref reader);
byte[] value = new byte[sByteArray.Length];
for (int i = 0; i < sByteArray.Length; i++)
{
value[i] = (byte)sByteArray[i];
}
return value;
}
public override void Write(Utf8JsonWriter writer, byte[] value, JsonSerializerOptions options)
{
writer.WriteStartArray();
foreach (var val in value)
{
writer.WriteNumberValue(val);
}
writer.WriteEndArray();
}
}

Answer 2

使用ASP.NET 6:

在您的模型中：

public class JsonRoot
{
// Add this attribute to your byte array(s).
[JsonConverter(typeof(JsonToByteArrayConverter))]
public byte[] ByteArray {get;set;}  
}

添加一个新类：

using System.Text.Json;
using System.Text.Json.Serialization;
internal sealed class JsonToByteArrayConverter : JsonConverter<byte[]?>
{
// Converts base64 encoded string to byte[].
public override byte[]? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
{
if (!reader.TryGetBytesFromBase64(out byte[]? result) || result == default)
{
throw new Exception("Add your fancy exception message here...");
}
return result;
}
// Converts byte[] to base64 encoded string.
public override void Write(Utf8JsonWriter writer, byte[]? value, JsonSerializerOptions options)
{
writer.WriteBase64StringValue(value);
}
}

Answer 3

一个简单的解决方案：

使用Newtonsoft.Json.JsonConvert.DeserializeObject<gt而不是JsonSerializer。反序列化<gt。它将解决问题。