Scala / Jerkson：在Json中指定Date对象的格式

Question

I am serializing an object containing a Date using the Jerkson Json library (wrapper for Jackson ):

import com.codahale.jerkson.Json
import java.util.Date

case class JTest(
    val dTest: Date
)

val jt = new JTest(new Date())
println(Json.generate(jt))

Which results in:

{"dTest":1353576079168}

Is there any way I can specify the format or override the generating function?

I realize that Json doesn't have a proper Date type, so the output (unix time in millis) is "correct". I'd like to have my Dates serialized as strings in the ISO 8601 (with time/timezone) format: 2007-04-05T01:12:22+0100 , as it's easily parsed and human readable. Date 's toString spits out Thu Nov 22 10:27:54 CET 2012 .

Answer 1

There are two issues here. Firstly, the minor issue of ISO8601 dates - these are achievable using SimpleDateFormat, eg

import java.text._
import java.util._
val d1 = new Date()
val sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ")
println(sdf.format(d1))

The formatter will parse as well as format. Remember not to share it between threads (instead always create an instance in local scope before use) because it isn't thread-safe.

Secondly, the more tricky issue of using dates automatically in Jerkson. This appears to be one feature of Jerkson that is inferior to Lift-json. The latter allows custom parser/formatter code to be inserted into the parsing layer. Jerkson does not, I think.

We got round this limitation simply by ignoring it. We like the superior performance of Jerkson, so we just use Long and String for our date transmission and we deal with the parsing separately. For example

case class JTest(val dTest: String) {
  lazy val dTestDate: Date = {
    val sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ")
    sdf.parse(dTest)
  }
}