来自 Json 与 Gson 的数据模型映射返回 null

Question

我有这个JSON

{
"Meta Data": {
"1: Symbol": "stock",
"2: Indicator": "SMA",
"3: Last Refreshed": "2017-07-25 09:50:00",
"4: Interval": "daily",
"5: Time Period": 3,
"6: Series Type": "open",
"7: Time Zone": "US/Eastern"
},
"Technical Analysis: SMA": {
"2017-07-25 09:50:00": {
"SMA": "266.6264"
},
"2017-07-24": {
"SMA": "265.9137"
},
"2017-07-21": {
"SMA": "265.3237"
}
}}

我已经映射了这些类，以便直接用gson库(Stock，MetaData，TechAnalysis，DayValue(填充模型：

public class Stock {
private MetaData metaData;
private TechAnalysis tech;

public MetaData getMetaData() {
return metaData;
}
public void setMetaData(MetaData metaData) {
this.metaData = metaData;
}
public TechAnalysis getTech() {
return tech;
}
public void setTech(TechAnalysis tech) {
this.tech = tech;
}}


public class MetaData {
private String symbol;
private String indicator;
private Date lastRefreshed;
private String interval;
private Integer period;
private String zone;

public String getSymbol() {
return symbol;
}
public void setSymbol(String symbol) {
this.symbol = symbol;
}
public String getIndicator() {
return indicator;
}
public void setIndicator(String indicator) {
this.indicator = indicator;
}
public Date getLastRefreshed() {
return lastRefreshed;
}
public void setLastRefreshed(Date lastRefreshed) {
this.lastRefreshed = lastRefreshed;
}
public String getInterval() {
return interval;
}
public void setInterval(String interval) {
this.interval = interval;
}
public Integer getPeriod() {
return period;
}
public void setPeriod(Integer period) {
this.period = period;
}
public String getZone() {
return zone;
}
public void setZone(String zone) {
this.zone = zone;
}}


public class TechAnalysis {

private List<DayValue> dayValuesList;
public List<DayValue> getDayValuesList() {
return dayValuesList;
}
public void setDayValuesList(List<DayValue> dayValuesList) {
this.dayValuesList = dayValuesList;
}}

public class DayValue {
private String value;
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}}

我在 JSON 响应上映射模型的代码是这样的：

public static Stock getStock(String json){
Gson gson = new Gson();  
return gson.fromJson(json, Stock.class); 
}

但 Stock 对象返回始终为空

Answer 1

类模型和 JSON 不兼容。例如，这个 JSON ...

"Meta Data": {
"1: Symbol": "stock",
"2: Indicator": "SMA",
"3: Last Refreshed": "2017-07-25 09:50:00",
"4: Interval": "daily",
"5: Time Period": 3,
"6: Series Type": "open",
"7: Time Zone": "US/Eastern"
}

。表示具有名为Meta Data的属性的类(这不是有效的属性名称(，并且"元数据"类将需要名为1: Symbol、2: Indicator等的属性(再次，无效的属性名称(。

您定义的类模型将与此 JSON 兼容：

{
"metaData": {
"symbol": "stock",
"indicator": "SMA",
"lastRefreshed": "2017-07-25 09:50:00",
"interval": "daily",
"period": 3,
"zone": "US/Eastern"
},
"techAnalysis": {
"dayValuesList": [
{
"value": "266.6264",
"dateTime": "2017-07-25 09:50:00"
}
]
}
}

尽管即使这样也需要在DayValue中添加dateTime属性。