使用Gson将JSON数组解析为Java列表 [英] Parsing JSON Array to Java List Using Gson

问题描述

从给定的JSON生成SimpleTestClass类型的List的最佳方法是什么，其中JSON中recipients数组中的值有一个新的SimpleTestClass对象，代码设置为出色地.

What is the best way from the given JSON to generate List of SimpleTestClass type where there's a new SimpleTestClass object for the values in the recipients array in the JSON with code set as well.

public class SimpleTestClass{
     String code;
     String recipient; 
}

JSON有效载荷:

{
     "code": 123,
     "recipients": [
        "888888",
        "222222"
     ]
}

推荐答案

如果JSON结构不适合POJO模型，则需要编写自定义反序列化器或创建适合JSON的新POJO模型，经过反序列化过程后，将其转换为所需的模型.在下面，您可以找到带有自定义反序列化器的解决方案，该解决方案使您可以非常灵活地处理给定的JSON:

If JSON structure does not fit to POJO model you need to write custom deserialiser or create a new POJO model which fits JSON and after deserialisation process convert it to required model. Below you can find solution with custom deserialiser which allow you to handle given JSON in a very flexible way:

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonArray;
import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParseException;
import com.google.gson.annotations.JsonAdapter;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.List;

public class GsonApp {

    public static void main(String[] args) {
        String json = "{\"code\": 123,\"recipients\": [\"888888\",\"222222\"]}";

        Gson gson = new GsonBuilder().create();

        List<Recipient> recipients = gson.fromJson(json, Recipients.class).getRecipients();
        recipients.forEach(System.out::println);
    }
}

class RecipientsJsonDeserializer implements JsonDeserializer<Recipients> {

    @Override
    public Recipients deserialize(JsonElement json, Type typeOfT,
        JsonDeserializationContext context) throws JsonParseException {
        List<Recipient> recipients = new ArrayList<>();

        JsonObject root = json.getAsJsonObject();
        String code = root.get("code").getAsString();
        JsonArray recipientsArray = root.getAsJsonArray("recipients");
        recipientsArray.forEach(item -> {
            recipients.add(new Recipient(code, item.getAsString()));
        });

        return new Recipients(recipients);
    }
}

@JsonAdapter(RecipientsJsonDeserializer.class)
class Recipients {

    private final List<Recipient> recipients;

    public Recipients(List<Recipient> recipients) {
        this.recipients = recipients;
    }

    // getters, toString
}

class Recipient {

    private final String code;
    private final String recipient;

    public Recipient(String code, String recipient) {
        this.code = code;
        this.recipient = recipient;
    }

    // getters, toString
}

上面的代码显示:

Recipient{code='123', recipient='888888'}
Recipient{code='123', recipient='222222'}

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