您可以使用GSON Liberary这样做。如果你不是坚持Jackson图书馆。希望你能从这部分得到答案。

public class JsonParse
 {
    public static void main(String... args)
    {
        Employee product = new Employee("JSON");
        Gson gson = new GsonBuilder().create(); 
        gson = new 
        GsonBuilder().excludeFieldsWithoutExposeAnnotation().create();
        String result = gson.toJson(product);
        System.out.println(result);
    }
 }
class Employee
{
  @Expose
  private byte [] name;
  public Employee(String name)
  {
     this.name = name.getBytes();
  }
}

以下是使用GSON自定义解析器的示例：

import com.google.gson.*;
import java.lang.reflect.Type;
import java.util.Map;
class GsonStringToBytesExample {
    // POJO
    static class SomeName {
      public byte[] message;
    }
    // custom deserializer capable of converting json string field to pojo's byte[] field
    static class SomeNameDeserializer implements JsonDeserializer<SomeName> {
      private final static Gson gson = new Gson();
      @Override
      public SomeName deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
        // reading json fields to map
        Map<String, JsonElement> fieldsMap = json.getAsJsonObject().asMap();
        // reading json string message
        String messageStr = fieldsMap.get("message").getAsString();
        // creating bytes array from string
        byte[] messageBytes = messageStr.getBytes();
        // creating GSON's JsonElement from bytes array
        JsonElement dataBytesJsonElement = gson.toJsonTree(messageBytes);
        // substituting json "message" field with bytes array object
        fieldsMap.put("message", dataBytesJsonElement);
        // finally deserializing to POJO
        return gson.fromJson(json, typeOfT);
    }
  }
  public static void main(String[] args) {
    String json = """
            {"message":"hi"}
            """;
    Gson gson = new GsonBuilder()
            // registering custom deserializer
            .registerTypeAdapter(SomeName.class, new SomeNameDeserializer())
            .create();
    SomeName someName = gson.fromJson(json, SomeName.class);
    // here we have pojo with bytes array from string
    System.out.println(new String(someName.message));
  }
}