blocks|key|874333|text|这个怎么样？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|874334|implicit+val+formats+=+net.liftweb.json.DefaultFormats
import+net.liftweb.json.JsonAST._
import+net.liftweb.json.Extraction._
import+net.liftweb.json.Printer._
val+m+=+Map[String,+String](
++++"a"+->+"theA",
++++"b"+->+"theB",
++++"c"+->+"theC",
++++"d"+->+"theD",
++++"e"+->+"theE"
)
println(compact(render(decompose(m))))|code-block|syntax|javascript|874335|输出：|874336|{"e":"theE","a":"theA","b":"theB","c":"theC","d":"theD"}|874337|编辑：|874338|对于scala.collections.mutable.Map，您应该首先将其转换为不可变的映射：.toMap|offset|length|style|CODE|874339|entityMap^0|0|0|0|0|0|2|T|1D|6|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|Y|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|Z|8|@$O|10|P|11|Q|R]|$O|12|P|13|Q|R]]|9|@]|A|$]]|$1|S|3|-4|5|6|7|14|8|@]|9|@]|A|$]]]|T|$]]

How about this?

<pre><code>implicit val formats = net.liftweb.json.DefaultFormats
import net.liftweb.json.JsonAST._
import net.liftweb.json.Extraction._
import net.liftweb.json.Printer._
val m = Map[String, String](
 "a" -&gt; "theA",
 "b" -&gt; "theB",
 "c" -&gt; "theC",
 "d" -&gt; "theD",
 "e" -&gt; "theE"
)
println(compact(render(decompose(m))))
</code></pre>

output:

<pre><code>{"e":"theE","a":"theA","b":"theB","c":"theC","d":"theD"}
</code></pre>

EDIT:

For a <code>scala.collections.mutable.Map</code>, you should convert it first to an immutable map: <code>.toMap</code>

blocks|key|657109|text|如果您使用的是最新的Scala+2.10.x及更高版本：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|657110|println(scala.util.parsing.json.JSONObject(m))|code-block|syntax|javascript|657111|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

If you are using the latest Scala 2.10.x and above :

<pre><code>println(scala.util.parsing.json.JSONObject(m))
</code></pre>

blocks|key|657176|text|您可以很容易地使用自己的代码(耶，没有依赖关系)。与前面提到的JSONObject不同，它执行基本的类型处理，并将执行递归：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|657177|import+scala.collection.mutable.ListBuffer

object+JsonConverter+{
++def+toJson(o:+Any)+:+String+=+{
++++var+json+=+new+ListBuffer[String]()
++++o+match+{
++++++case+m:+Map[_,_]+=>+{
++++++++for+(+(k,v)+<-+m+)+{
++++++++++var+key+=+escape(k.asInstanceOf[String])
++++++++++v+match+{
++++++++++++case+a:+Map[_,_]+=>+json+%2B=+"\""+%2B+key+%2B+"\":"+%2B+toJson(a)
++++++++++++case+a:+List[_]+=>+json+%2B=+"\""+%2B+key+%2B+"\":"+%2B+toJson(a)
++++++++++++case+a:+Int+=>+json+%2B=+"\""+%2B+key+%2B+"\":"+%2B+a
++++++++++++case+a:+Boolean+=>+json+%2B=+"\""+%2B+key+%2B+"\":"+%2B+a
++++++++++++case+a:+String+=>+json+%2B=+"\""+%2B+key+%2B+"\":\""+%2B+escape(a)+%2B+"\""
++++++++++++case+_+=>+;
++++++++++}
++++++++}
++++++}
++++++case+m:+List[_]+=>+{
++++++++var+list+=+new+ListBuffer[String]()
++++++++for+(+el+<-+m+)+{
++++++++++el+match+{
++++++++++++case+a:+Map[_,_]+=>+list+%2B=+toJson(a)
++++++++++++case+a:+List[_]+=>+list+%2B=+toJson(a)
++++++++++++case+a:+Int+=>+list+%2B=+a.toString()
++++++++++++case+a:+Boolean+=>+list+%2B=+a.toString()
++++++++++++case+a:+String+=>+list+%2B=+"\""+%2B+escape(a)+%2B+"\""
++++++++++++case+_+=>+;
++++++++++}
++++++++}
++++++++return+"["+%2B+list.mkString(",")+%2B+"]"
++++++}
++++++case+_+=>+;
++++}
++++return+"{"+%2B+json.mkString(",")+%2B+"}"
++}

++private+def+escape(s:+String)+:+String+=+{
++++return+s.replaceAll("\""+,+"\\\\\"");
++}
}|code-block|syntax|javascript|657178|您可以在操作中看到它，如下所示|657179|println(JsonConverter.toJson(
++++Map("a"->+1,
++++++++"b"+->+Map(
++++++++++++"nes\"ted"+->+"yeah{\"some\":true"),
++++++++++++"c"+->+List(
++++++++++++++++1,
++++++++++++++++2,
++++++++++++++++"3",
++++++++++++++++List(
++++++++++++++++++++true,
++++++++++++++++++++false,
++++++++++++++++++++true,
++++++++++++++++++++Map(
++++++++++++++++++++++++"1"->"two",
++++++++++++++++++++++++"3"->"four"
++++++++++++++++++++)
++++++++++++++++)
++++++++++++)
++++++++)
++++)
)

{"a":1,"b":{"nes\"ted":"yeah{\"some\":true"},"c":[1,2,"3",[true,false,true,{"1":"two","3":"four"}]]}|657180|(它是我编写的Coinbase+GDAX库的一部分，参见util.scala)|657181|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/jar-o/gdax-scala/blob/master/src/main/scala/GDAX/util.scala^0|V|A|0|0|0|0|S|A|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|11|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|12|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|13|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|14|8|@]|D|@$9|15|A|16|1|17]]|E|$]]|$1|Q|3|-4|5|6|7|18|8|@]|D|@]|E|$]]]|R|$S|$5|T|U|V|E|$W|X]]]]

You can roll your own pretty easily (yay, no dependencies). This one does basic handling of types and will do recursion unlike <code>JSONObject</code> that was mentioned:

<pre><code>import scala.collection.mutable.ListBuffer

object JsonConverter {
 def toJson(o: Any) : String = {
 var json = new ListBuffer[String]()
 o match {
 case m: Map[_,_] =&gt; {
 for ( (k,v) &lt;- m ) {
 var key = escape(k.asInstanceOf[String])
 v match {
 case a: Map[_,_] =&gt; json += "\"" + key + "\":" + toJson(a)
 case a: List[_] =&gt; json += "\"" + key + "\":" + toJson(a)
 case a: Int =&gt; json += "\"" + key + "\":" + a
 case a: Boolean =&gt; json += "\"" + key + "\":" + a
 case a: String =&gt; json += "\"" + key + "\":\"" + escape(a) + "\""
 case _ =&gt; ;
 }
 }
 }
 case m: List[_] =&gt; {
 var list = new ListBuffer[String]()
 for ( el &lt;- m ) {
 el match {
 case a: Map[_,_] =&gt; list += toJson(a)
 case a: List[_] =&gt; list += toJson(a)
 case a: Int =&gt; list += a.toString()
 case a: Boolean =&gt; list += a.toString()
 case a: String =&gt; list += "\"" + escape(a) + "\""
 case _ =&gt; ;
 }
 }
 return "[" + list.mkString(",") + "]"
 }
 case _ =&gt; ;
 }
 return "{" + json.mkString(",") + "}"
 }

 private def escape(s: String) : String = {
 return s.replaceAll("\"" , "\\\\\"");
 }
}
</code></pre>

You can see it in action like

<pre><code>println(JsonConverter.toJson(
 Map("a"-&gt; 1,
 "b" -&gt; Map(
 "nes\"ted" -&gt; "yeah{\"some\":true"),
 "c" -&gt; List(
 1,
 2,
 "3",
 List(
 true,
 false,
 true,
 Map(
 "1"-&gt;"two",
 "3"-&gt;"four"
 )
 )
 )
 )
 )
)

{"a":1,"b":{"nes\"ted":"yeah{\"some\":true"},"c":[1,2,"3",[true,false,true,{"1":"two","3":"four"}]]}
</code></pre>

(It's part of a Coinbase GDAX library I've written, see <a href="https://github.com/jar-o/gdax-scala/blob/master/src/main/scala/GDAX/util.scala" rel="noreferrer" title="util.scala">util.scala</a>)

blocks|key|657226|text|如果你正在使用play框架，你可以使用这个简单的方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|657227|import+play.api.libs.json._

Json.toJson(<your_map>)|code-block|syntax|javascript|657228|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You can use this simple way if you are using play framework:

<pre><code>import play.api.libs.json._

Json.toJson(&lt;your_map&gt;)
</code></pre>

blocks|key|657264|text|这段代码将转换许多不同的对象，除了内置的scala.util.parsing.json._外，不需要任何库。它不能正确处理边缘情况，比如使用整数作为键的Map。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|657265|import+scala.util.parsing.json.{JSONArray,+JSONObject}
def+toJson(arr:+List[Any]):+JSONArray+=+{
++JSONArray(arr.map+{
++++case+(innerMap:+Map[String,+Any])+=>+toJson(innerMap)
++++case+(innerArray:+List[Any])++++++=>+toJson(innerArray)
++++case+(other)++++++++++++++++++++++=>+other
++})
}
def+toJson(map:+Map[String,+Any]):+JSONObject+=+{
++JSONObject(map.map+{
++++case+(key,+innerMap:+Map[String,+Any])+=>
++++++(key,+toJson(innerMap))
++++case+(key,+innerArray:+List[Any])+=>
++++++(key,+toJson(innerArray))
++++case+(key,+other)+=>
++++++(key,+other)
++})
}|code-block|syntax|javascript|657266|entityMap^0|K|P|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

This code will convert many different objects, and doesn't require any libraries beyond the built-in the <code>scala.util.parsing.json._</code>. It won't properly handle edge cases like Maps with integers as keys.

<pre><code>import scala.util.parsing.json.{JSONArray, JSONObject}
def toJson(arr: List[Any]): JSONArray = {
 JSONArray(arr.map {
 case (innerMap: Map[String, Any]) =&gt; toJson(innerMap)
 case (innerArray: List[Any]) =&gt; toJson(innerArray)
 case (other) =&gt; other
 })
}
def toJson(map: Map[String, Any]): JSONObject = {
 JSONObject(map.map {
 case (key, innerMap: Map[String, Any]) =&gt;
 (key, toJson(innerMap))
 case (key, innerArray: List[Any]) =&gt;
 (key, toJson(innerArray))
 case (key, other) =&gt;
 (key, other)
 })
}
</code></pre>

blocks|key|874541|text|通过@Raja补充答案。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|874542|对于那些嵌套的对象，我在本地修改了类，使其具有所需的toString()，如下所示：|offset|length|style|CODE|874543|case+class+MList[T]()+extends+MutableList[T]+{+++override+def+toString()+=+"["+%2B+this.toList.mkString(",")+%2B+"]"+}|874544|然后在Map对象中，我使用这个MList而不是标准的List。这样，通过调用JSONObject(map).toString()，我的map对象就可以很好地打印出来。|874545|entityMap^0|0|Q|A|0|0|36|0|F|5|Q|4|12|Q|1V|3|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|O|8|@$D|P|E|Q|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|R|8|@$D|S|E|T|F|G]]|9|@]|A|$]]|$1|J|3|K|5|6|7|U|8|@$D|V|E|W|F|G]|$D|X|E|Y|F|G]|$D|Z|E|10|F|G]|$D|11|E|12|F|G]]|9|@]|A|$]]|$1|L|3|-4|5|6|7|13|8|@]|9|@]|A|$]]]|M|$]]

Supplementing the answer by @Raja.

For those nested object, I locally modify the class to have my wanted <code>toString()</code> like this way:

<code>case class MList[T]() extends MutableList[T] {
 override def toString() = "[" + this.toList.mkString(",") + "]"
}</code>

Then inside the Map object, I use this <code>MList</code> instead of the standard <code>List</code>. That way, my <code>map</code> object prints out fine by calling <code>JSONObject(map).toString()</code>.

So I have a Map in Scala like this:

<pre><code>val m = Map[String, String](
 "a" -&gt; "theA",
 "b" -&gt; "theB",
 "c" -&gt; "theC",
 "d" -&gt; "theD",
 "e" -&gt; "theE"
)
</code></pre>

and I want to serialize this structure into a JSON string using lift-json.

Do any of you know how to do this?

How do you serialize a Map to JSON in Scala?

JSON

因此，我在Scala中有一个这样的Map：val m = Map[String, String](    "a" -> "theA",    "b" -> "theB",    "c" -> "theC",    "d" -> "theD",    "e" -> "theE")我想使用lift-json将这个结构序列化...

问如何在Scala中将Map序列化为JSON？
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