我正在尝试使用外部NYtimes API。以下是示例数据输出示例：
{
"status": "OK",
"copyright": "Copyright (c) 2016 The New York Times Company. All Rights Reserved.",
"section": "home",
"last_updated": "2016-10-20T19:57:45-04:00",
"num_results": 30,
"results": [{
"section": "Briefing",
"subsection": "",
"title": "Election, Dodgers, Duterte: Your Thursday Evening Briefing",
"abstract": "Here’s what you need to know at the end of the day.",
"url": "abc.co",
"byline": "By KAREN ZRAICK and MERRILL D. OLIVER",
"item_type": "Article",
"updated_date": "2016-10-20T18:32:41-04:00",
"created_date": "2016-10-20T17:58:30-04:00",
"published_date": "2016-10-20T17:58:30-04:00",
"material_type_facet": "",
"kicker": "",
"des_facet": [],
"org_facet": [],
"per_facet": [],
"geo_facet": [],
"multimedia": [{
"url": "abc.co",
"format": "Standard Thumbnail",
"height": 75,
"width": 75,
"type": "image",
"subtype": "photo",
"caption": "",
"copyright": "Damon Winter/The New York Times"
}, {
"url": "abc.co",
"format": "thumbLarge",
"height": 150,
"width": 150,
"type": "image",
"subtype": "photo",
"caption": "",
"copyright": "Damon Winter/The New York Times"
}, {
"url": "abc.co",
"format": "Normal",
"height": 127,
"width": 190,
"type": "image",
"subtype": "photo",
"caption": "",
"copyright": "Damon Winter/The New York Times"
}, {
"url": "abc.co",
"format": "mediumThreeByTwo210",
"height": 140,
"width": 210,
"type": "image",
"subtype": "photo",
"caption": "",
"copyright": "Damon Winter/The New York Times"
}, {
"url": "abc.co",
"format": "superJumbo",
"height": 1365,
"width": 2048,
"type": "image",
"subtype": "photo",
"caption": "",
"copyright": "Damon Winter/The New York Times"
}],
"short_url": "http://abc.co"
}
]
}
这是bean定义
//Headline.class
public class Headline {
@JsonProperty("status")
String status;
@JsonProperty("copyright")
String copyright;
@JsonProperty("section")
String section;
@JsonProperty("last_updated")
String last_updated;
@JsonProperty("num_results")
int num_results;
@JsonProperty("results")
List<Story> results;
`
//Story.class
@JsonProperty("section")
String section;
@JsonProperty("subsection")
String subsection;
@JsonProperty("title")
String title;
@JsonProperty("abstract")
String storyAbstract;
@JsonProperty("url")
String url;
@JsonProperty("byline")
String byline;
@JsonProperty("item_type")
String item_type;
@JsonProperty("updated_date")
String updated_date;
@JsonProperty("created_date")
String created_date;
@JsonProperty("published_date")
String published_date;
@JsonProperty("material_type_facet")
String material_type_facet;
@JsonProperty("kicker")
String kicker;
/*@JsonProperty("des_facet")
List des_facet;
@JsonProperty("org_facet")
List org_facet;
@JsonProperty("per_facet")
List per_facet;
@JsonProperty("geo_facet")
List geo_facet;*/
@JsonProperty("multimedia")
List<Media> multimedia;
@JsonProperty("short_url")
String short_url;
//Media.class
@JsonProperty("url")
String url;
@JsonProperty("format")
String format;
@JsonProperty("height")
int height;
@JsonProperty("width")
int width;
@JsonProperty("type")
String type;
@JsonProperty("subtype")
String subtype;
@JsonProperty("caption")
String caption;
@JsonProperty("copyright")
String copyright;
这是我的来电者：
RestTemplate restTemplate = new RestTemplate();
MappingJackson2HttpMessageConverter jsonConverter = new MappingJackson2HttpMessageConverter();
jsonConverter.setSupportedMediaTypes(Arrays.asList(new MediaType("text","json",MappingJackson2HttpMessageConverter.DEFAULT_CHARSET)));
restTemplate.getMessageConverters().add(jsonConverter);
Headline headline = restTemplate.getForObject("http://abc/svc/topstories/v1/home.json?api-key=key",Headline.class);
logger.info("Headline"+headline.toString());
我拨打电话时遇到的例外情况是：
Exception in thread "main" org.springframework.http.converter.HttpMessageNotReadableException: Could not read JSON: Can not construct instance of java.util.ArrayList: no String-argument constructor/factory method to deserialize from String value ('')
at [Source: java.io.PushbackInputStream@22d9d; line: 1, column: 1185] (through reference chain: NYTimes.Payload.Headline["results"]->java.util.ArrayList[0]->NYTimes.Story.Story["multimedia"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not construct instance of java.util.ArrayList: no String-argument constructor/factory method to deserialize from String value ('')
at [Source: java.io.PushbackInputStream@22d9d; line: 1, column: 1185] (through reference chain: NYTimes.Payload.Headline["results"]->java.util.ArrayList[0]->NYTimes.Story.Story["multimedia"])
我一直试图理解它为什么不反序列化。如果字符串值为空 - 那么它应该导致空列表？
答案 0 :(得分：0)
由于您收到的json响应而发生此异常 -
{
"status": "OK",
"copyright": "Copyright (c) 2016 The New York Times Company. All Rights Reserved.",
"section": "home",
"last_updated": "2016-10-20T19:57:45-04:00",
"num_results": 30,
"results": [{
"section": "Briefing",
"subsection": "",
"title": "Election, Dodgers, Duterte: Your Thursday Evening Briefing",
"abstract": "Here’s what you need to know at the end of the day.",
"url": "abc.co",
"byline": "By KAREN ZRAICK and MERRILL D. OLIVER",
"item_type": "Article",
"updated_date": "2016-10-20T18:32:41-04:00",
"created_date": "2016-10-20T17:58:30-04:00",
"published_date": "2016-10-20T17:58:30-04:00",
"material_type_facet": "",
"kicker": "",
"des_facet": [],
"org_facet": [],
"per_facet": [],
"geo_facet": [],
"multimedia": "",
"short_url": "http://abc.co"
}
]
}
＆＃34;多媒体＆＃34; field是一个空字符串
所以你需要验证你的json并相应地映射你的pojo。