据观察，Scala 2.10似乎已经破坏了一些老的库（至少暂时是这样），比如Jerkson和lift-json。
目标可用性如下：
case class Person(name: String, height: String, attributes: Map[String, String], friends: List[String])
//to serialize
val person = Person("Name", ....)
val json = serialize(person)
//to deserialize
val sameperson = deserialize[Person](json)
但我在查找使用Scala 2.10生成和反序列化Json的好方法方面遇到了困难。
在Scala 2.10中有最佳实践方法可以做到这一点吗？
Jackson 是一个快速处理 JSON 的 Java 库。Jerkson 项目封装了 Jackson，但似乎已经被放弃了。我已经转而使用 Jackson 的 Scala Module 来将数据序列化和反序列化为本地 Scala 数据结构。
要获取它，请在您的 build.sbt 中包含以下内容：
libraryDependencies ++= Seq(
"com.fasterxml.jackson.module" %% "jackson-module-scala" % "2.1.3",
...
)
那么你的示例将直接适用于以下Jackson包装器（我从jackson-module-scala测试文件中提取了它）：
import java.lang.reflect.{Type, ParameterizedType}
import com.fasterxml.jackson.databind.ObjectMapper
import com.fasterxml.jackson.module.scala.DefaultScalaModule
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.core.`type`.TypeReference;
object JacksonWrapper {
val mapper = new ObjectMapper()
mapper.registerModule(DefaultScalaModule)
def serialize(value: Any): String = {
import java.io.StringWriter
val writer = new StringWriter()
mapper.writeValue(writer, value)
writer.toString
}
def deserialize[T: Manifest](value: String) : T =
mapper.readValue(value, typeReference[T])
private [this] def typeReference[T: Manifest] = new TypeReference[T] {
override def getType = typeFromManifest(manifest[T])
}
private [this] def typeFromManifest(m: Manifest[_]): Type = {
if (m.typeArguments.isEmpty) { m.runtimeClass }
else new ParameterizedType {
def getRawType = m.runtimeClass
def getActualTypeArguments = m.typeArguments.map(typeFromManifest).toArray
def getOwnerType = null
}
}
}
implicit lazy val CodecCustomer: CodecJson[Customer] =
casecodec6(Customer.apply, Customer.unapply)("id","name","address","city","state","user_id")
这将提升您的类，使其具有.asJson方法，将其转换为字符串。它还将提升字符串类，以提供一个.decodeOption[List[Customer]]方法来解析字符串。它可以很好地处理您的类中的选项。这是一个工作类，带有通过测试和运行的主要方法，您可以将其放入argonaut的git克隆中，以确保一切正常运行：
package argonaut.example
import org.specs2.{ScalaCheck, Specification}
import argonaut.CodecJson
import argonaut.Argonaut._
case class Customer(id: Int, name: String, address: Option[String],
city: Option[String], state: Option[String], user_id: Int)
class CustomerExample extends Specification with ScalaCheck {
import CustomerExample.CodecCustomer
import CustomerExample.customers
def is = "Stackoverflow question 12591457 example" ^
"round trip customers to and from json strings " ! {
customers.asJson.as[List[Customer]].toOption must beSome(customers)
}
}
object CustomerExample {
implicit lazy val CodecCustomer: CodecJson[Customer] =
casecodec6(Customer.apply, Customer.unapply)("id","name","address","city","state","user_id")
val customers = List(
Customer(1,"one",Some("one street"),Some("one city"),Some("one state"),1)
, Customer(2,"two",None,Some("two city"),Some("two state"),2)
, Customer(3,"three",Some("three address"),None,Some("three state"),3)
, Customer(4,"four",Some("four address"),Some("four city"),None,4)
)
def main(args: Array[String]): Unit = {
println(s"Customers converted into json string:\n ${customers.asJson}")
val jsonString =
"""[
| {"city":"one city","name":"one","state":"one state","user_id":1,"id":1,"address":"one street"}
| ,{"city":"two city","name":"two","state":"two state","user_id":2,"id":2}
| ,{"name":"three","state":"three state","user_id":3,"id":3,"address":"three address"}
| ,{"city":"four city","name":"four","user_id":4,"id":4,"address":"four address"}
|]""".stripMargin
var parsed: Option[List[Customer]] = jsonString.decodeOption[List[Customer]]
println(s"Json string turned back into customers:\n ${parsed.get}")
}
}
开发人员也很乐意帮助新手，并且能够及时响应。
现在有一个支持Scala 2.10的Jerkson分支，网址是https://github.com/randhindi/jerkson。
进行序列化：
import net.liftweb.json._
import Extraction._
implicit val formats = DefaultFormats
case class Person(...)
val person = Person(...)
val personJson = decompose(person) // Results in a JValue
// Person Json is a JValue here.
personJson.extract[Person]
如果这不是你遇到麻烦的部分，请告诉我，我可以尝试修改我的答案以使其更有帮助。