1
我試着從春天RestTemplate的東西。我試圖讀取這個JSON數據：JSON Data。數據是一個鍵值對，其中鍵是「geonames」，值是「geoname」對象的數組。RestTemplate：無法將對象的實例反序列化爲START_OBJECT標記
我有一個Geoname類來處理輸入。這個班級裏還有getter和setter。然後，我有隻運行一個主要方法調用RestTemplate對象app類：
@JsonIgnoreProperties(ignoreUnknown = true)
public class Geoname {
private String name;
private long lat;
private long lng;
private String countrycode;
}
App.java
public class App
{
public static void main(String[] args)
{
String jsonUrl = "http://api.geonames.org/citiesJSON?north=44.1&south=-9.9&east=-22.4&west=55.2&lang=de&username=demo";
RestTemplate template = new RestTemplate();
ResponseEntity<Geoname[]> entity = template.getForEntity(jsonUrl, Geoname[].class);
List<Geoname> data = Arrays.asList(entity.getBody());
System.out.print("Success!");
}
}
這是我的錯誤輸出：
Exception in thread "main" org.springframework.http.converter.HttpMessageNotReadableException: Could not read JSON: Can not deserialize instance of com.declan.Geoname[] out of START_OBJECT token
at [Source: [email protected]3ac5; line: 1, column: 1]; nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of com.declan.Geoname[] out of START_OBJECT token
at [Source: [email protected]3ac5; line: 1, column: 1]
at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:208)
at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.read(AbstractJackson2HttpMessageConverter.java:200)
at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:96)
at org.springframework.web.client.RestTemplate$ResponseEntityResponseExtractor.extractData(RestTemplate.java:812)
at org.springframework.web.client.RestTemplate$ResponseEntityResponseExtractor.extractData(RestTemplate.java:796)
at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:576)
at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:529)
at org.springframework.web.client.RestTemplate.getForEntity(RestTemplate.java:261)
at com.declan.App.main(App.java:20)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:134)
Caused by: com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of com.declan.Geoname[] out of START_OBJECT token
at [Source: [email protected]3ac5; line: 1, column: 1]
at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:148)
at com.fasterxml.jackson.databind.DeserializationContext.mappingException(DeserializationContext.java:835)
at com.fasterxml.jackson.databind.DeserializationContext.mappingException(DeserializationContext.java:831)
at com.fasterxml.jackson.databind.deser.std.ObjectArrayDeserializer.handleNonArray(ObjectArrayDeserializer.java:232)
at com.fasterxml.jackson.databind.deser.std.ObjectArrayDeserializer.deserialize(ObjectArrayDeserializer.java:139)
at com.fasterxml.jackson.databind.deser.std.ObjectArrayDeserializer.deserialize(ObjectArrayDeserializer.java:17)
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:3560)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2660)
at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:205)
... 13 more
我已經嘗試過這種設置，我試着使用getForObject就像在春天的文檔，我已經嘗試在這裏搜索stackoverflow和使用映射到列表的常見問題。我甚至嘗試創建一個僅包含數組或Geoname對象的Geonames類，但這種方法也無法正常工作......始終存在相同的錯誤。也許，我沒有正確閱讀Json，但如果有人能借給我一雙眼睛，我會很感激。 ：D
乾杯！
編輯
好吧，我現在有這個新的類，它現在做的JSON數據的GET請求。但是，在調試之後，ResponseEntity主體將數組設置爲null。我是否需要手動實例化Geonames中的數組？
@JsonIgnoreProperties(ignoreUnknown = true)
public class Geonames {
@JsonProperty("geonames")
Geoname[] geonames;
public void setGeonames(Geonames[] geonames) {
this.geonames = geonames;
}
public void getGeonames() {
return geonames;
}
}