使用Play解析Scala（2.10.1）中的JSON文件

Question

我是scala的一名新手，我在這里要做的就是使用scala解析一個JSON文件，然后將其打印出來。 我在編譯時遇到無法解決的錯誤。 在此先感謝您的任何幫助。 PFB scala代碼，SBT文件，JSON文件和錯誤：

json_example.scala

import scala.io.Source
import play.api.libs.json._
import play.api.libs.json._


object Test extends App  {


val line :String = "Foo";

val filename = "users.json"
for (line <- Source.fromFile(filename).getLines().mkString) {
println(line);
val json: JsValue = Json.parse(line);

 }
 }

JSON文件（ users.json ）

{"users":[
    {"ID":"1","firstName":"John", "lastName":"Doe"},
    {"ID":"2","firstName":"Anna", "lastName":"Smith"},
    {"ID":"3","firstName":"Peter", "lastName":"Jones"}
    {"ID":"1","firstName":"Stewie", "lastName":"Doe"},
    {"ID":"2","firstName":"Chris", "lastName":"Smith"},
    {"ID":"3","firstName":"Louis", "lastName":"Jones"}
    {"ID":"2","firstName":"Brian", "lastName":"Smith"},
    {"ID":"3","firstName":"Meg", "lastName":"Jones"}

]}

SBT文件（simple.sbt）

lazy val root = (project in file(".")).

settings(
name := "JSON_GRAPHX",
version := "1.0",
scalaVersion := "2.10.1",

libraryDependencies ++= Seq("com.github.scala-incubator.io" %% "scala-io-file" % "0.4.2",
                       "com.typesafe.play" %% "play-json" % "2.3.4"),

                      resolvers += "Typesafe Repo" at "http://repo.typesafe.com/typesafe/releases/"


)

錯誤

[info] Set current project to JSON_GRAPHX (in build file:/F:/Graphx_app/JSON_GRAPHX/)
[info] Compiling 1 Scala source to F:\Graphx_app\JSON_GRAPHX\target\scala-2.10\classes...
[error] F:\Graphx_app\JSON_GRAPHX\json_example.scala:15: overloaded method value parse with alternatives:
[error]   (input: Array[Byte])play.api.libs.json.JsValue <and>
[error]   (input: String)play.api.libs.json.JsValue
[error]  cannot be applied to (Char)
[error]  val json: JsValue = Json.parse(line);
[error]                           ^
[error] one error found
[error] (compile:compileIncremental) Compilation failed
[error] Total time: 4 s, completed Aug 18, 2016 8:51:22 PM

Answer 1

要構建JSON對象，您可以直接在mkString返回的String調用parse方法。 就像是：

val json = Json.parse(Source.fromFile(filename).getLines().mkString)

通過做：

for (line <- Source.fromFile(filename).getLines().mkString)

實際上，您正在遍歷Json String的所有字符-這就是為什么您收到無法將parse方法應用於Char的錯誤的原因。

擁有JSON對象后，您可以將其縮小打印：

println(Json.stringify(json))

或者您可以以可讀格式打印它：

println(Json.prettyPrint(son))