使用 Jackson 和 WebClient 将 json 数组反序列化为对象

Question

我在使用 Spring 反序列化 json 数组时遇到问题。我收到来自服务的 json 响应：

[
    {
        "symbol": "XRPETH",
        "orderId": 12122,
        "clientOrderId": "xxx",
        "price": "0.00000000",
        "origQty": "25.00000000",
        "executedQty": "25.00000000",
        "status": "FILLED",
        "timeInForce": "GTC",
        "type": "MARKET",
        "side": "BUY",
        "stopPrice": "0.00000000",
        "icebergQty": "0.00000000",
        "time": 1514558190255,
        "isWorking": true
    },
    {
        "symbol": "XRPETH",
        "orderId": 1212,
        "clientOrderId": "xxx",
        "price": "0.00280000",
        "origQty": "24.00000000",
        "executedQty": "24.00000000",
        "status": "FILLED",
        "timeInForce": "GTC",
        "type": "LIMIT",
        "side": "SELL",
        "stopPrice": "0.00000000",
        "icebergQty": "0.00000000",
        "time": 1514640491287,
        "isWorking": true
    },
    ....
]

我使用来自 Spring WebFlux 的新 WebClient 得到这个 json，这里是代码：

@Override
    public Mono<AccountOrderList> getAccountOrders(String symbol) {
        return binanceServerTimeApi.getServerTime().flatMap(serverTime -> {
            String apiEndpoint = "/api/v3/allOrders?";
            String queryParams = "symbol=" +symbol.toUpperCase() + "&timestamp=" + serverTime.getServerTime();
            String signature = HmacSHA256Signer.sign(queryParams, secret);
            String payload = apiEndpoint + queryParams + "&signature="+signature;
            log.info("final endpoint:"+ payload);
            return this.webClient
                    .get()
                    .uri(payload)
                    .accept(MediaType.APPLICATION_JSON)
                    .retrieve()
                    .bodyToMono(AccountOrderList.class)
                    .log();
        });
    }

账户订单列表

public class AccountOrderList {

    private List<AccountOrder> accountOrders;

    public AccountOrderList() {
    }

    public AccountOrderList(List<AccountOrder> accountOrders) {
        this.accountOrders = accountOrders;
    }

    public List<AccountOrder> getAccountOrders() {
        return accountOrders;
    }

    public void setAccountOrders(List<AccountOrder> accountOrders) {
        this.accountOrders = accountOrders;
    }
}

AccountOrder 是一个映射字段的简单 pojo。

实际上，当我点击 get 时，它说：

org.springframework.core.codec.DecodingException: JSON decoding error: Cannot deserialize instance of `io.justin.demoreactive.domain.AccountOrder` out of START_ARRAY token; nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `io.justin.demoreactive.domain.AccountOrder` out of START_ARRAY token
 at [Source: UNKNOWN; line: -1, column: -1]

如何使用新的 webflux 模块正确反序列化 json？我究竟做错了什么？

更新 05/02/2018

两个答案都正确。他们完美地解决了我的问题，但最后我决定使用稍微不同的方法：

@Override
    public Mono<List<AccountOrder>> getAccountOrders(String symbol) {
        return binanceServerTimeApi.getServerTime().flatMap(serverTime -> {
            String apiEndpoint = "/api/v3/allOrders?";
            String queryParams = "symbol=" +symbol.toUpperCase() + "&timestamp=" + serverTime.getServerTime();
            String signature = HmacSHA256Signer.sign(queryParams, secret);
            String payload = apiEndpoint + queryParams + "&signature="+signature;
            log.info("final endpoint:"+ payload);
            return this.webClient
                    .get()
                    .uri(payload)
                    .accept(MediaType.APPLICATION_JSON)
                    .retrieve()
                    .bodyToFlux(AccountOrder.class)
                    .collectList()
                    .log();
        });
    }

另一种方法是 return 直接使用 A Flux，这样您就不必将其转换为列表。（这就是通量：n 个元素的集合）。

Answer 1

要与 AccountOrderList class 匹配的响应，json 必须像这样

{
  "accountOrders": [
    {
        "symbol": "XRPETH",
        "orderId": 12122,
        "clientOrderId": "xxx",
        "price": "0.00000000",
        "origQty": "25.00000000",
        "executedQty": "25.00000000",
        "status": "FILLED",
        "timeInForce": "GTC",
        "type": "MARKET",
        "side": "BUY",
        "stopPrice": "0.00000000",
        "icebergQty": "0.00000000",
        "time": 1514558190255,
        "isWorking": true
    },
    {
        "symbol": "XRPETH",
        "orderId": 1212,
        "clientOrderId": "xxx",
        "price": "0.00280000",
        "origQty": "24.00000000",
        "executedQty": "24.00000000",
        "status": "FILLED",
        "timeInForce": "GTC",
        "type": "LIMIT",
        "side": "SELL",
        "stopPrice": "0.00000000",
        "icebergQty": "0.00000000",
        "time": 1514640491287,
        "isWorking": true
    },
    ....
]
}

这就是错误消息所说的“out of START_ARRAY token”

如果您无法更改响应，请更改您的代码以像这样接受数组

this.webClient.get().uri(payload).accept(MediaType.APPLICATION_JSON)
                        .retrieve().bodyToMono(AccountOrder[].class).log();

您可以将此数组转换为 List，然后 return。

Answer 2

您的回复很简单 List<AccountOrder>。但是，您的 POJO 已包装 List<AccountOrder>。所以，根据你的 POJO，你的 JSON 应该是

{
  "accountOrders": [
    {

但是，你的JSON是

[
    {
       "symbol": "XRPETH",
       "orderId": 12122,
        ....

因此，存在不匹配且反序列化失败。您需要更改为

bodyToMono(AccountOrder[].class)

Answer 3

关于您对问题的更新答案，使用 bodyToFlux 不必要地低效，而且在语义上也没有多大意义，因为您真的不想要订单流。您想要的只是能够将响应解析为列表。

由于类型擦除，

bodyToMono(List<AccountOrder>.class) 将不起作用。您需要能够在运行时保留类型，Spring 为此提供了 ParameterizedTypeReference：

bodyToMono(new ParameterizedTypeReference<List<AccountOrder>>() {})

使用 Jackson 和 WebClient 将 json 数组反序列化为对象

Deserialize a json array to objects using Jackson and WebClient

java

spring

jackson

spring-boot

spring-webflux