Question

我在Snake_Case中使用带有属性的json字符串为＆＃34; Country_Code＆＃34;：＆＃34; US＆＃34;，＆＃34; Group_Member_Code＆＃34;：null

我必须将其映射到具有camelCase属性的对象

class Output{

    @JsonProperty("countryCode")
    private String countryCode;
    @JsonProperty("groupMemberCode")
    private String groupMemberCode;

}

要按照其他线程的建议执行此操作，我将自定义PropertyNamingStratergy创建为

public class CustomCase extends PropertyNamingStrategy.PropertyNamingStrategyBase {

    public CustomCase() {
    }

    public String translate(String input) {
        if (input == null) {
            return input;
        } else {
            char[] arr = input.toCharArray();
            StringBuilder result = new StringBuilder();
            result.append(Character.toLowerCase(arr[0]));

            for (int i = 1; i < arr.length; i++) {
                if (arr[i] == '_') {
                    result.append(Character.toUpperCase(arr[i + 1]));
                    i++;
                } else {
                    result.append(arr[i]);
                }
            }
            return result.toString();
        }

    }
}

我正在将其设置为我正在反序列化的类

 JAXBContext jaxbContext =     JAXBContext.newInstance(InstinctFraudCheckXMLStringResponse.class);
 Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
 InstinctFraudCheckXMLStringResponse fraudResponse = (InstinctFraudCheckXMLStringResponse)
         unmarshaller.unmarshal(new ByteArrayInputStream(response.getBytes()));

 XmlMapper xmlMapper = new XmlMapper();
 JsonNode node = xmlMapper.readTree(fraudResponse.getInstinctFraudCheckXMLStringResult().getBytes());

 ObjectMapper mapper = new ObjectMapper();
 mapper.configure(MapperFeature.ACCEPT_CASE_INSENSITIVE_PROPERTIES, true);
 mapper.setPropertyNamingStrategy(new CustomCase());
 fraudDecision = mapper.writeValueAsString(node);
 FraudResponse fraudResponse1 = mapper.readValue(fraudDecision,FraudResponse.class);
 System.out.println(fraudResponse1);

但似乎mu NamingStratergy无法正常工作，它无法将snake_case转换为驼峰并将其映射到Object，因为我的FraudResponse总是来NUll。

请帮我找出为什么NamingStratgery无法正常工作。

Answer 1

首先，按如下所示更改Output类

class  Output {
        // Value from JsonProperty annotation removed. Will handle in naming strategy
        @JsonProperty
        private String countryCode;

        @JsonProperty
        private String groupMemberCode;

    }

然后为您的ObjectMapper

添加命名策略

//For jackson < 2.7
objectMapper.setPropertyNamingStrategy(
            PropertyNamingStrategy.CAMEL_CASE_TO_LOWER_CASE_WITH_UNDERSCORES);


//For jackson >= 2.7
objectMapper.setPropertyNamingStrategy(
                PropertyNamingStrategy.PropertyNamingStrategy.SNAKE_CASE);

示例

ObjectMapper objectMapper = new ObjectMapper(); objectMapper.setPropertyNamingStrategy(PropertyNamingStrategy.SNAKE_CASE); Output output = new Output(); output.countryCode="US"; output.groupMemberCode = "ABC"; System.out.println(objectMapper.writeValueAsString(output));

<强>打印

{"country_code":"US","group_member_code":"ABC"}

Answer 2

我认为你可以试试这个解决方案（在我的情况下工作）：

删除@JsonProperty注释。

使用objectMapper指定策略：

mapper.configure(MapperFeature.ACCEPT_CASE_INSENSITIVE_PROPERTIES, true);
mapper.setPropertyNamingStrategy(PropertyNamingStrategy.CAMEL_CASE_TO_LOWER_CASE_WITH_UNDERSCORES);

工作示例：

class Output {

    private String countryCode;

    public String getCountryCode() {
        return countryCode;
    }

    public void setCountryCode(String countryCode) {
        this.countryCode = countryCode;
    }

}

String data = "{\"Country_Code\":\"US\"}";

ObjectMapper mapper = new ObjectMapper();
mapper.configure(MapperFeature.ACCEPT_CASE_INSENSITIVE_PROPERTIES, true);
mapper.setPropertyNamingStrategy(PropertyNamingStrategy.CAMEL_CASE_TO_LOWER_CASE_WITH_UNDERSCORES);

mapper.readValue(data, Output.class);

自定义PropertyNamingStrategy无法在jackson

2 个答案: