Java 如何使用 Jackson 反序列化以秒为单位的时间戳？
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How do I deserialize timestamps that are in seconds with Hymanson?
提问by Drew Stephens
I've got some JSON that has timestamps in seconds (i.e. a Unix timestamp):
我有一些以秒为单位的时间戳（即 Unix 时间戳）：
{"foo":"bar","timestamp":1386280997}
Asking Hymanson to deserialize this into an object with a DateTime field for the timestamp results in 1970-01-17T01:11:25.983Z, a time shortly after the epoch because Hymanson is assuming it to be in milliseconds. Aside from ripping apart the JSON and adding some zeros, how might I get Hymanson to understand the secondstimestamp?
要求 Hymanson 将其反序列化为一个带有 DateTime 字段作为时间戳的对象，结果是在1970-01-17T01:11:25.983Z纪元之后不久，因为 Hymanson 假设它以毫秒为单位。除了撕开 JSON 并添加一些零之外，我如何让 Hymanson 理解秒时间戳？
采纳答案by Drew Stephens
I wrote a custom deserializerto handle timestamps in seconds (Groovy syntax).
我编写了一个自定义解串器来以秒为单位处理时间戳（Groovy 语法）。
class UnixTimestampDeserializer extends JsonDeserializer<DateTime> {
Logger logger = LoggerFactory.getLogger(UnixTimestampDeserializer.class)
@Override
DateTime deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException {
String timestamp = jp.getText().trim()
try {
return new DateTime(Long.valueOf(timestamp + '000'))
} catch (NumberFormatException e) {
logger.warn('Unable to deserialize timestamp: ' + timestamp, e)
return null
}
}
}
And then I annotated my POGO to use that for the timestamp:
然后我注释了我的 POGO 以将其用于时间戳：
class TimestampThing {
@JsonDeserialize(using = UnixTimestampDeserializer.class)
DateTime timestamp
@JsonCreator
public TimestampThing(@JsonProperty('timestamp') DateTime timestamp) {
this.timestamp = timestamp
}
}
回答by sherpya
@JsonFormat(shape=JsonFormat.Shape.STRING, pattern="s")
public Date timestamp;
edit: vivek-kothari suggestion
编辑：vivek-kothari 建议
@JsonFormat(shape=JsonFormat.Shape.NUMBER, pattern="s")
public Timestamp timestamp;
回答by Priidu Neemre
A very similar approach to that of @DrewStephens's which uses the Java SE TimeUnitAPI (introduced in JDK1.5) instead of plain String concatenation and is thus (arguably) a little bit cleaner and more expressive:
一种与@DrewStephens 的方法非常相似的方法，它使用 Java SE TimeUnitAPI（在 中引入JDK1.5）而不是普通的字符串连接，因此（可以说）更清晰，更具表现力：
public class UnixTimestampDeserializer extends JsonDeserializer<Date> {
@Override
public Date deserialize(JsonParser parser, DeserializationContext context)
throws IOException, JsonProcessingException {
String unixTimestamp = parser.getText().trim();
return new Date(TimeUnit.SECONDS.toMillis(Long.valueOf(unixTimestamp)));
}
}
Specifying your custom deserializer (UnixTimestampDeserializer) on the affected Datefield(s):
UnixTimestampDeserializer在受影响的Date字段上指定您的自定义解串器 ( )：
@JsonDeserialize(using = UnixTimestampDeserializer.class)
private Date updatedAt;
回答by svarog
I had this exact issue, except my ZonedDateTime objects got turned to unix-timestamps (seconds) and I needed them in milliseconds (to initialize JS Date objects on the browser).
我有这个确切的问题，除了我的 ZonedDateTime 对象变成了 unix-timestamps（秒）并且我需要它们以毫秒为单位（在浏览器上初始化 JS Date 对象）。
Implementing a custom serializer/deserializer looked like too much work for something that should be pretty straightforward, so I looked elsewhere and found that I can just configure the object mapper for the desired result.
实现自定义序列化器/反序列化器对于应该非常简单的事情来说看起来工作量太大，所以我查看了其他地方，发现我可以只为所需的结果配置对象映射器。
Because my application already overrides the default ObjectMapper provided by Jersey, I just had to disable SerializationFeature.WRITE_DATE_TIMESTAMPS_AS_NANOSECONDS.
因为我的应用程序已经覆盖了 Jersey 提供的默认 ObjectMapper，所以我只需要禁用SerializationFeature.WRITE_DATE_TIMESTAMPS_AS_NANOSECONDS.
Here's my code
这是我的代码
@Provider
public class RPObjectMapperProvider implements ContextResolver<ObjectMapper> {
final ObjectMapper defaultObjectMapper;
public RPObjectMapperProvider() {
defaultObjectMapper = new ObjectMapper();
// this turned ZonedDateTime objects to proper seconds timestamps
defaultObjectMapper.enable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
// disable to serialize dates for millis timestamps
defaultObjectMapper.disable(SerializationFeature.WRITE_DATE_TIMESTAMPS_AS_NANOSECONDS);
// using Java8 date time classes
defaultObjectMapper.registerModule(new JavaTimeModule());
}
@Override
public ObjectMapper getContext(Class<?> type) {
return defaultObjectMapper;
}
}
And that's it
就是这样
