Jackson - 使用动态键反序列化 json

当您具有动态键时，可以使用 Map<K、V>。键的类型和值取决于您的需要。

最简单的方法是 。为此，您需要一个 TypeReference<T>：Map<String, Object>

ObjectMapper mapper = new ObjectMapper();
Map<String, Object> map = 
    mapper.readValue(json, new TypeReference<Map<String, Object>>() {});

假设您的密钥是有效日期，则可以使用 .Map<LocalDate, Object>

需要以下依赖项：

<dependency>
    <groupId>com.fasterxml.jackson.datatype</groupId>
    <artifactId>jackson-datatype-jsr310</artifactId>
    <version>${jackson.version}</version>
</dependency>

然后，您可以拥有：

ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new JavaTimeModule());
Map<LocalDate, Object> map =
    mapper.readValue(json, new TypeReference<Map<LocalDate, Object>>() {});

最后，您可以将动态键的值映射到 Java 类。我们称之为：Foo

public class Foo {

    private Integer downloads;

    @JsonProperty("re_downloads")
    private Integer reDownloads;

    private Integer updates;

    private Integer returns;

    @JsonProperty("net_downloads")
    private Integer netDownloads;

    private Integer promos;

    private String revenue;

    @JsonProperty("returns_amount")
    private String returnsAmount;

    @JsonProperty("edu_downloads")
    private Integer eduDownloads;

    private Integer gifts;

    @JsonProperty("gift_redemptions")
    private Integer giftRedemptions;

    // Default constructor, getters and setters omitted
}

然后你可以有一个：Map<LocalDate, Foo>

ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new JavaTimeModule());
Map<LocalDate, Foo> map =
        mapper.readValue(json, new TypeReference<Map<LocalDate, Foo>>() {});