scala_map

scala map 学习

在看scalatra的源码时，发现其中定义了一个MultiMap类，如下：

//MultiMap的伴生对象
object MultiMap {

def apply(): MultiMap = new MultiMap

def apply[SeqType <: Seq[String]](wrapped: Map[String, SeqType]): MultiMap = new MultiMap(wrapped)

def empty: MultiMap = apply()

//隐式函数
implicit def map2MultiMap(map: Map[String, Seq[String]]): MultiMap = new MultiMap(map)

}

class MultiMap(wrapped: Map[String, Seq[String]] = Map.empty)
extends Map[String, Seq[String]] {

def get(key: String): Option[Seq[String]] = {
(wrapped.get(key) orElse wrapped.get(key + "[]"))
}

/*This class provides a simple way to get unique objects for equal strings.
 *  Since symbols are interned, they can be compared using reference equality.
 *  Instances of `Symbol` can be created easily with Scala's built-in quote
 *  mechanism.*/
 //相同的字符串获得同一个对象
def get(key: Symbol): Option[Seq[String]] = get(key.name)

def +[B1 >: Seq[String]](kv: (String, B1)): MultiMap = {
new MultiMap(wrapped + kv.asInstanceOf[(String, Seq[String])])
}

def -(key: String): MultiMap = new MultiMap(wrapped - key)

def iterator: Iterator[(String, Seq[String])] = wrapped.iterator

override def default(a: String): Seq[String] = wrapped.default(a)

}

map用法：

val mapTest  = Map[String,String] ("key1" -> "faeff")
println(mapTest.get("key1").get)

val map2 =mapTest - "key1"