这是一个挺能展现Scala编程方式的例子，对正在熟悉Scala这门语言的开发者很有帮助。

Representing JSON

用Scala来表达JSON(Java Script Object Notation)结构，

{  "firstname" : "John",  "lastname" : "Smith",  "address" : {    "street" : "21 2nd Street",    "state" : "NY",    "postalCode" : 10021  },  "phoneNumbers" : [    { "type" : "home", "number" : "212 555-1234" },    { "type" : "fax", "number : "646 555-4567" }  ] }

Scala表示JSON的一种类结构：

abstract class JSONcase class JSeq (elems: List[JSON]) extends JSONcase class JObj (bindings: Map[String, JSON]) extends JSONcase class JNum (num: Double) extends JSONcase class JStr (str: String) extends JSONcase class JBool(b: Boolean) extends JSONcase object JNull extends JSON

Example

val data = JObj(Map(  "firstName" -> JStr("John"),  "lastName" -> JStr("Smith"),  "address" -> JObj(Map(    "street" -> JStr("21 2nd Street"),    "state" -> JStr("NY"),    "postalCode" -> JNum(10021)  )),  "phoneNumbers" -> JSeq(List(    JObj(Map(      "type" -> JStr("home"), "number" -> JStr("212 555-1234")    )),    JObj(Map(      "type" -> JStr("fax"), "number"-> JStr("646 555-4567")    ))   ))))

利用Pattern Matching，展示一个输出JSON string串的方法：

def show(json: JSON): String = json match {  case JSeq(elems) =>    "[" + (elems map show mkString ", ") + "]"  case JObj(bindings) =>    val assocs = bindings map {      case (key, value) => "\"" + key + "\": " + show(value)    }  "{" + (assocs mkString ", ") + "}"  case JNum(num) => num.toString  case JStr(str) => '\"' + str + '\"'  case JBool(b) => b.toString  case JNull => "null"}

参考自

全文完 :)