在 Spring 应用程序中使用 RestTemplate 从 JSON 中获取值

Question

我尝试从 JSON 中解析值：

{"BTC_BCN":{"id":7,"last":"0.00000086","lowestAsk":"0.00000086","highestBid":"0.00000085","percentChange":"0.14666666","baseVolume":"368.86654762","quoteVolume":"498378738.00151879","isFrozen":"0","high24hr":"0.00000086","low24hr":"0.00000068"},"BTC_ETH":{"id":8,"last":"0.00003800","lowestAsk":"0.00003815","highestBid":"0.00003800","percentChange":"0.12326337","baseVolume":"34.17037464","quoteVolume":"955538.55551651","isFrozen":"0","high24hr":"0.00003883","low24hr":"0.00003221"}}

我感兴趣的值是"id":8,"last":"0.00003800"。 我有 RestTemplate 的 bean：

@Bean
public RestTemplate restTemplate(RestTemplateBuilder builder) {
    return builder.build();
}

每 5 秒通过 API 询问网站的那个

@Bean
public CommandLineRunner run(RestTemplate restTemplate) throws Exception {
        return args -> {
            while(true)
            {
                BTC_Poloniex btc_poloniex = restTemplate.getForObject(
                        "https://poloniex.com/public?command=returnTicker", BTC_Poloniex.class);
                log.info(btc_poloniex.toString());
                TimeUnit.SECONDS.sleep(5);
            }           
        };
    }

和读取值的类：

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;

@JsonIgnoreProperties(ignoreUnknown = true)
public class BTC_Poloniex {
private BTC_BCN BTC_BCN;

public BTC_Poloniex() {}


public BTC_BCN getBTC_BCN() {
    return BTC_BCN;
}

public void setBTC_BCN(BTC_BCN btc_bcn)
{
    this.BTC_BCN = btc_bcn;
}

@Override
public String toString() {
    return "BTC_Poloniex{" +
            "BTC_BCN=" + BTC_BCN +
            '}';
}
}

和类（我认为如果是内部类会更好）

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;

@JsonIgnoreProperties(ignoreUnknown = true)
public class BTC_BCN {
private long id;
private long last;
private long lowestAsk;

public BTC_BCN(){}

public long getId() {
    return id;
}

public void setId(long id) {
    this.id = id;
}

public long getLast() {
    return last;
}

public void setLast(long last) {
    this.last = last;
}

public long getLowestAsk() {
    return lowestAsk;
}

public void setLowestAsk(long lowestAsk) {
    this.lowestAsk = lowestAsk;
}

public String toString()
{
    return "BTC_BCN{" +
            " id='" + id + '\'' +
            " last'= " + last + '\'' +
            " lowestAsk'= " + lowestAsk + '\'' +
            '}';
}
}

当我尝试获取这些值时，我总是有 null

2018-01-12 14:00:14.829  INFO 18017 --- [           main] com.example.demo.BitbayApplication       : BTC_ETH{BTC_ETH=null}

为什么会这样？我可以轻松阅读更简单的 JSON，但对此有问题。

Answer 1

简单的解决方案是使用地图。 示例如下。

使用此代码，您可以访问 json 中的每个字段 :)

我希望我的解决方案对你来说足够好:)

@Service
public class RestTemplateService {

@Autowired
RestTemplate restTemplate;


public void getInfoFromPoloniex() {
    HashMap<String,Map> answer = restTemplate.getForObject("https://poloniex.com/public?command=returnTicker",
            new HashMap<>().getClass());

    answer.values().forEach(a -> System.out.println(a.toString()));

    System.out.println(answer.get("BTC_GAME").getClass().toString());

    answer.get("BTC_GAME").keySet().stream().forEach(k -> System.out.println(k.toString()));


}

}

Answer 2

BTC_Poloniex 类中定义的变量

private BTC_ETH BTC_ETH;

应该是

    private BTC_ETH BTC_BCN;

因为json变量是

BTC_BCN

这应该与 json CLASS 中的变量名相同。