Lombok/Jackson-POJO用于​​json数组 [英] Lombok/Jackson - POJO for a json array

问题描述

我有一个需要从服务器接收(反序列化)并发送(序列化)到另一台服务器的json数组:

I have a json array that I need to receive(de-serialize) from a server and send (serialize) to another server:

示例:

[
  {
    "car-name": "string",
    "parts": [
      "engine",
      "wheels"
    ]
  }
]

我首先编写了以下POJO来表示此Json数组:

I started with writing the following POJO to represent this Json array:

import lombok.Builder;
import lombok.Singular;
import lombok.Value;


@Builder
@Value
public class Car {

    private String carName;
    @Singular("part")
    private List<String> parts;
}

与此:

1. 我能够使用Lombok构建对象，如下所示:

Car myCar = Car.builder().carName("Tesla").part("engine").part("wheels").build();

1. 使用类似unmarshal().json(Jackson, Car.class)的命令进行解组.

1. Unmarshal using something like unmarshal().json(Jackson, Car.class).

虽然1)和2)有效，但它们没有给我实际代表上述json示例的对象.

While 1) and 2) work, they do NOT give me objects that actually represent the json example above.

他们改为:

  {
    "car-name": "string",
    "parts": [
      "engine",
      "wheels"
    ]
  }

我尝试使用父类，如下所示:

I tried using a parent class as below:

import lombok.Builder;
import lombok.Singular;
import lombok.Value;

@Builder
@Value
public class Vehicle {

    private List<Car> vehicles;
}

但这也给了我一个错误的对象(请注意，车辆"键与上面示例中的键相对):

But this also gives me a wrong object (notice the "vehicles" key Vs what I have in my above Example):

  {
    "vehicles": {
        "car-name": "string",
        "parts": [
             "engine",
             "wheels"
             ]
        }
}

如何编写一个代表此JSON数组的POJO，最好使用Lombok?还是杰克逊?

How can I write a POJO that represents this JSON array, preferably using Lombok? Or Jackson?

推荐答案

与lombok无关的问题，但我设法找到了解决该问题的方法

Theres nothing to do with lombok for your problem, But I've managed to found a workaround for the question

创建自定义的Serializer和SerializerModifier

Create a custom Serializer and SerializerModifier

汽车序列化器

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.ser.std.StdSerializer;

import java.io.IOException;

public class CarSerializer extends StdSerializer<Car> {
    private JsonSerializer<Object> defaultSerializer = null;

    public CarSerializer(JsonSerializer<Object> defaultSerializer) {
        super(Car.class);
        this.defaultSerializer = defaultSerializer;
    }

    public CarSerializer() {
        super(Car.class);
    }

    @Override
    public void serialize(Car value, JsonGenerator jgen, SerializerProvider provider) throws IOException {
        jgen.writeStartArray();

        defaultSerializer.serialize(value, jgen, provider);

        jgen.writeEndArray();
    }
}

CarSerializerModifier

import com.fasterxml.jackson.databind.BeanDescription;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializationConfig;
import com.fasterxml.jackson.databind.ser.BeanSerializerModifier;

public class CarSerializerModifier extends BeanSerializerModifier {

    @Override
    public JsonSerializer<?> modifySerializer(SerializationConfig config, BeanDescription beanDesc, JsonSerializer<?> serializer) {

        if (beanDesc.getBeanClass().equals(Car.class)) {
            return new CarSerializer((JsonSerializer<Object>) serializer);
        }

        return serializer;
    }
}

然后将ObjectMapper配置为使用CarSerializerModifier

Car myCar = Car.builder().carName("Tesla").part("engine").part("wheels").build();

ObjectMapper mapper = new ObjectMapper();
SimpleModule module = new SimpleModule();
module.setSerializerModifier(new CarSerializerModifier());
mapper.registerModule(module);

log.info(mapper.writeValueAsString(myCar));

您可以在此处阅读更多我做到了.

You car read here more about what I did.

如果您还想将ObjectMapper用于Web请求和响应序列化，请阅读文章

If you want to use the ObjectMapper also for your web requests and response serialization read that article

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