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数组期间遇到问题。我从服务获得此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Spring WebFlux的新WebClient获取此json，代码如下：

@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();
        });
    }

AccountOrderList

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是映射字段的简单pojo。

实际上，当我点击“ get”时，它会说：

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

两个答案都是正确的。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();
        });
    }

替代方法是直接返回A Flux，因此您不必将其转换为列表。（这就是通量：n个元素的集合）。

Answer 1

关于您对问题的更新答案，使用bodyToFlux不必要的低效并且在语义上也没有多大意义，因为您并不真正想要订单流。您想要的只是能够将响应解析为列表。

bodyToMono(List<AccountOrder>.class)由于类型擦除而无法工作。您需要能够在运行时保留类型，Spring 提供ParameterizedTypeReference了这一点：

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

Answer 2

为了使响应与AccountOrderList类匹配，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
    },
    ....
]
}

这就是错误消息说“ START_ARRAY令牌不足 ”的意思

如果您无法更改响应，请更改代码以接受Array，如下所示

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，然后返回。

Answer 3

您的回答很简单List<AccountOrder>。但是，您的 POJO 已将List<AccountOrder>. 所以，根据你的 POJO，你JSON应该是

{
  "accountOrders": [
    {

但是，你JSON的

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

因此，存在不匹配和反序列化失败。您需要更改为

bodyToMono(AccountOrder[].class)