【问题讨论】：
Object 类型的字段，所以它可以是任何东西。
expirityString、expirityObject，如果两者都指定了不同的值，则抛出异常）。
标签： java json rest web-services deserialization
为简单起见，我将仅使用示例中的卡片对象，我不会将其包装为另一个对象。为了避免示例中的重复，我将使用这个基类来保存公共字段：
public abstract class BaseCard {
private String brand;
private String fundingMethod;
private String scheme;
//setters and getters
}
你的选择很少。
选项 1：
如果您知道从哪个 api 获得响应，则可以有两个类，每个类都以特定于 api 的格式保存expiry。从 api 1 获取数据时使用：
public class CardApi1 extends BaseCard {
private String expiry;
//setters and getters
}
对于 api 2：
public class CardApi2 extends BaseCard {
private Expiry expiry;
//setters and getters
}
到期对象如下所示：
public class Expiry {
private String month;
private String year;
//setters and getters
}
如果您正在调用 api 1，则反序列化为 CardApi1，否则为 CardApi2。
选项2：设置过期字段Object，这样任何东西都可以反序列化到其中。
public class CardApiMixed extends BaseCard {
private Object expiry;
//setters and getters
public String getExpiryAsString() {
return (String) this.expiry;
}
public Map<String, Object> getExpiryAsMap() {
@SuppressWarnings("unchecked")
Map<String, Object> expiry = (Map<String, Object>) this.expiry;
return expiry;
}
}
这样，无论您调用哪个 api，您都可以反序列化为一个类。缺点是，在检索expiry的时候，还是要知道数据来自哪个api，所以要使用正确的方法。
选项 3： 编写自定义反序列化器，无论使用哪个 api，都能正确解析字段。我个人会选择这个选项。解串器是这样的：
public class ExpiryResolvingCardDeserializer extends StdDeserializer<CardApiResolved> {
public ExpiryResolvingCardDeserializer() {
super(CardApiResolved.class);
}
@Override
public CardApiResolved deserialize(JsonParser parser, DeserializationContext context) throws IOException {
JsonNode node = parser.getCodec().readTree(parser);
CardApiResolved card = new CardApiResolved();
card.setBrand(node.get("brand").asText());
card.setFundingMethod(node.get("fundingMethod").asText());
card.setScheme(node.get("scheme").asText());
JsonNode expiryNode = node.get("expiry");
Expiry expiry = new Expiry();
if (expiryNode.isObject()) {
//that's for api 2
expiry.setMonth(expiryNode.get("month").asText());
expiry.setYear(expiryNode.get("year").asText());
} else {
//for api 1
String text = expiryNode.asText();
//assuming format is always mmYY, you can handle it in differently if there are other options
int splitIndex = 2;
expiry.setMonth(text.substring(0, splitIndex));
expiry.setYear(text.substring(splitIndex));
}
card.setExpiry(expiry);
return card;
}
}
总结一下，当expiry节点是对象时，像对象一样处理，从中获取月和年数据，如果是字符串，则将其拆分以提取月和年。像这样无论格式如何，expiry 总是被解析为Expiry 类。卡片类将如下所示：
@JsonDeserialize(using = ExpiryResolvingCardDeserializer.class)
public class CardApiResolved extends BaseCard {
private Expiry expiry;
//setters and getters
}
注意JsonDeserialize 注释指定了用于此类型的反序列化器。最后，一些单元测试可以使用并检查结果。 api 响应是测试资源中的文件。
public class CardApiTests {
private final ObjectMapper mapper = new ObjectMapper();
@Test
public void testCardApi1() throws Exception {
InputStream inputStream = ClassLoader.getSystemResourceAsStream("card-api-1.json");
//map to CardApi1, when calling api 1
CardApi1 result = this.mapper.readValue(inputStream, CardApi1.class);
assertEquals("0139", result.getExpiry());
}
@Test
public void testCardApi2() throws Exception {
InputStream inputStream = ClassLoader.getSystemResourceAsStream("card-api-2.json");
//map to CardApi2, when calling api 2
CardApi2 result = this.mapper.readValue(inputStream, CardApi2.class);
assertEquals("1", result.getExpiry().getMonth());
assertEquals("39", result.getExpiry().getYear());
}
@Test
public void testCardApiMixed_Api1() throws Exception {
InputStream inputStream = ClassLoader.getSystemResourceAsStream("card-api-1.json");
CardApiMixed result = this.mapper.readValue(inputStream, CardApiMixed.class);
assertEquals("0139", result.getExpiryAsString());
}
@Test
public void testCardApiMixed_Api2() throws Exception {
InputStream inputStream = ClassLoader.getSystemResourceAsStream("card-api-2.json");
CardApiMixed result = this.mapper.readValue(inputStream, CardApiMixed.class);
assertEquals("1", result.getExpiryAsMap().get("month"));
assertEquals("39", result.getExpiryAsMap().get("year"));
}
@Test
public void testCardApiResolved_Api1() throws Exception {
InputStream inputStream = ClassLoader.getSystemResourceAsStream("card-api-1.json");
CardApiResolved result = this.mapper.readValue(inputStream, CardApiResolved.class);
assertEquals("01", result.getExpiry().getMonth());
assertEquals("39", result.getExpiry().getYear());
}
@Test
public void testCardApiResolved_Api2() throws Exception {
InputStream inputStream = ClassLoader.getSystemResourceAsStream("card-api-2.json");
CardApiResolved result = this.mapper.readValue(inputStream, CardApiResolved.class);
assertEquals("1", result.getExpiry().getMonth());
assertEquals("39", result.getExpiry().getYear());
}
}
【讨论】：
您能否分享一下到期字段是如何准备的？喜欢
"expiery":"0139" = 月+年。 如果字段是这样准备的，那么您可以保留字符串或列表的变量类型，您需要稍作修改。你会根据给定的例子给出一个想法。
public class App {
private static final HttpClient httpClient = HttpClient.newBuilder()
.version(HttpClient.Version.HTTP_1_1)
.connectTimeout(Duration.ofSeconds(10))
.build();
public static void main(String[] args) throws IOException, InterruptedException {
HttpRequest request = HttpRequest.newBuilder()
.GET()
.uri(URI.create("https://jsonmock.abc.com/api/articles?page=3"))
.setHeader("User-Agent", "Java 11 HttpClient Bot") // add request header
.build();
HttpResponse<String> response = httpClient.send(request, HttpResponse.BodyHandlers.ofString());
// print response headers
HttpHeaders headers = response.headers();
headers.map().forEach((k, v) -> System.out.println(k + ":" + v));
String responseBody = response.body();
ObjectMapper mapper = new ObjectMapper();
Object newJsonNode = mapper.readValue(responseBody, Object.class);
Map<String, Object> objectMap = (Map) newJsonNode;
if (objectMap.get("expiry") instanceof List) {
//if I assume that expiry string created by appending month and year
List<Map<String, Object>> list = (List) objectMap.get("expiry");
Map<String, Object> map = list.get(0);
String exp = (String) map.get("month") + (String) map.get("year");
objectMap.put("expiry", exp);
//then parse to direct object
} else if (objectMap.get("expiry") instanceof String) {
//then cast to dto
//you can apply reverse logic here, i.e string to map
}
}
}
【讨论】：