![](/img/trans.png)
[英]How do I override a Java map when converting a JSON to Java Object using GSON?
[英]How do I map a heterogeneous JSON array to a Java object?
我通過 API 下載了大量的歷史加密市場數據。 它的格式如下:
[
[1601510400000,"4.15540000","4.16450000","4.15010000","4.15030000","4483.01000000",1601510459999,"18646.50051400",50,"2943.27000000","12241.83706500","0"],
...
[1609490340000,"4.94020000","4.95970000","4.93880000","4.94950000","5307.62000000",1609490399999,"26280.03711000",98,"3751.46000000","18574.22402400","0"]
]
我認為它是一個 arrays 數組,內部包含異構類型(總是相同的類型以相同的順序)。 作為中間步驟,我已將其保存到文本文件中,但我想將其讀回並將 map 保存到此類對象的數組中:
public class MinuteCandle {
private long openTime;
private double openValue;
private double highValue;
private double lowValue;
private double closeValue;
private double volume;
private long closeTime;
private double quoteAssetVolume;
private int numberOfTrades;
private double takerBuyBaseAssetVolume;
private double takerBuyQuoteAssetVolume;
private double someGarbageData;
//...
}
我正在使用 Spring 框架和 jackson 庫進行 json 映射。 這是可行的還是我應該以某種方式手動解析文本?
我將分兩步執行此操作:
List<Object>
。List<Object>
轉換為MinuteCandle
object 並將這些對象收集到MinuteCandle
列表中。import java.io.File;
import java.util.ArrayList;
import java.util.List;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
public class Main {
public static void main(String[] args) throws Exception {
ObjectMapper objectMapper = new ObjectMapper();
File file = new File("example.json");
List<List<Object>> lists = objectMapper.readValue(file, new TypeReference<List<List<Object>>>() {});
List<MinuteCandle> minuteCandles = new ArrayList<>();
for (List<Object> list : lists) {
minuteCandles.add(MinuteCandle.createFromList(list));
}
}
}
可以通過在MinuteCandle
class 中添加 static 方法來實現從List<Object>
到MinuteCandle
的轉換(上面的第 2 步)。
public static MinuteCandle createFromList(List<Object> list) {
MinuteCandle m = new MinuteCandle();
m.openTime = (Long) list.get(0);
m.openValue = Double.parseDouble((String) list.get(1));
m.highValue = Double.parseDouble((String) list.get(2));
m.lowValue = Double.parseDouble((String) list.get(3));
m.closeValue = Double.parseDouble((String) list.get(4));
m.volume = Double.parseDouble((String) list.get(5));
m.closeTime = (Long) list.get(6);
m.quoteAssetVolume = Double.parseDouble((String) list.get(7));
m.numberOfTrades = (Integer) list.get(8);
m.takerBuyBaseAssetVolume = Double.parseDouble((String) list.get(9));
m.takerBuyQuoteAssetVolume = Double.parseDouble((String) list.get(10));
m.someGarbageData = Double.parseDouble((String) list.get(11));
return m;
}
使用JsonFormat並在您將 shape 指定為ARRAY
的地方用它注釋您的 class :
@JsonFormat(shape = JsonFormat.Shape.ARRAY)
class MinuteCandle
此外,如果您想存儲價格,請考慮使用BigDecimal
而不是double
。
也可以看看:
假設文件中存儲的文本是有效的JSON,類似於How to Read JSON data from txt file in Java? 一個可以使用com.google.gson.Gson
如下:
import com.google.gson.Gson;
import java.io.FileReader;
import java.io.Reader;
public class Main {
public static void main(String[] args) throws Exception {
try (Reader reader = new FileReader("somefile.txt")) {
Gson gson = new Gson();
MinuteCandle[] features = gson.fromJson(reader, MinuteCandle[].class);
}
}
}
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.