java - JSON 在响应中返回空值

Question

我的响应给了我null值，但是当我在fiddler中运行相同的值时，我得到了大量数据。我编写的代码非常少，并使用在线工具来生成代码。我想知道我哪里搞砸了。

    Publications response = null ;
    // First open URL connection (using JDK; similar with other libs)
    try {
        URL url = new URL(
                "http://myserver:myport/Mobile/GetPublications");
        HttpURLConnection connection = (HttpURLConnection)url.openConnection() ;
        connection.setDoInput(true);
        connection.setDoOutput(true);
        connection.setRequestMethod("POST") ;
        connection.setRequestProperty("Content-Type", "application/json") ;
        // and other configuration if you want, timeouts etc
        // then send JSON request
        Publications request = new Publications(); // POJO with getters or public fields
        ObjectMapper mapper = new ObjectMapper(); 
        mapper.writeValue(connection.getOutputStream(), request);
        // and read response
        response = mapper.readValue(
                connection.getInputStream(), Publications.class);
    } catch (JsonGenerationException e) {
        e.printStackTrace();
        fail() ;
    } catch (JsonMappingException e) {
        e.printStackTrace();
        fail() ;
    } catch (IOException e) {
        e.printStackTrace();
        fail() ;
    }
    assertNotNull(response) ;
    assertTrue(response.getPublicationInfo() != null) ;
//      assertTrue(response.getPublicationInfo().size() > 0);
//      assertNotNull( ((PublicationInfo)response.getPublicationInfo().get(0)).getPublicationTitle() != null) ;

出版物 POJO 是

import com.fasterxml.jackson.*

@JsonSerialize(include = JsonSerialize.Inclusion.NON_NULL)
@Generated("com.googlecode.jsonschema2pojo")
@JsonPropertyOrder({ "ErrorInfo", "PublicationInfo" })
public class Publications {

@JsonProperty("ErrorInfo")
private Object ErrorInfo;

@JsonProperty("PublicationInfo")
private List<PublicationInfo> PublicationInfo = new ArrayList<PublicationInfo>();
private Map<String, Object> additionalProperties = new HashMap<String, Object>();

@JsonProperty("ErrorInfo")
public Object getErrorInfo() {
    return ErrorInfo;
}

@JsonProperty("ErrorInfo")
public void setErrorInfo(Object ErrorInfo) {
    this.ErrorInfo = ErrorInfo;
}

@JsonProperty("PublicationInfo")
public List<PublicationInfo> getPublicationInfo() {
    return PublicationInfo;
}

@JsonProperty("PublicationInfo")
public void setPublicationInfo(
        List<PublicationInfo> PublicationInfo) {
    this.PublicationInfo = PublicationInfo;
}

@JsonAnyGetter
public Map<String, Object> getAdditionalProperties() {
    return this.additionalProperties;
}

@JsonAnySetter
public void setAdditionalProperties(String name, Object value) {
    this.additionalProperties.put(name, value);
}
}

我在 assertTrue(response.getPublicationInfo().size() > 0); 处遇到测试用例失败。但 fiddler 返回以下内容

{
"SpecialPublications": {
    "ErrorInfo": null,
    "SpecialPublicationInfo": [
        {
            "Date": "2/3/2010",
            "URL": "SOME URL HERE",
            "Description": "So much to do so less time."
        },
        {
            "Date": "2/4/2010",
            "URL": "SOME MORE URL HERE",
            "Description": "I need more time"
        }
   ]
}
}

Answer 1

您应该在所有位置将 @JsonProperty("PublicationInfo") 更改为 @JsonProperty("SpotlightPublicationInfo")。您的属性名称错误。

@JsonProperty 的语义是:json 中出现的属性名称。

编辑 还要从 json 中删除虚假属性名称。替换:

response = mapper.readValue(connection.getInputStream(), Publications.class);

与:

JsonNode responseJson = mapper.readTree(connection.getInputStream());
response = mapper.readValue(responseJson.traverse().getValueAsString("SpecialPublications"), Publications.class);

这将去除您尝试解析的对象的虚假 {"SpecialPublications": ... } 包装器。