如何在Scala中使用lift-json解析JSON? [英] How to parse JSON with lift-json in Scala?

问题描述

当我尝试解析 json 对象时，出现以下错误.

When I am trying parse the json object I am getting the below error.

import net.liftweb.json._

object SarahEmailPluginConfigTest {
  implicit val formats = DefaultFormats

  case class Mailserver(url: String, username: String, password: String)

  val json = parse("""{"url": "imap.yahoo.com", "username": "myusername", "password": "mypassword" }""")

  def main(args: Array[String]) {
    val m = json.extract[Mailserver]
    println(m.url)
    println(m.username)
    println(m.password)
  }
}

我添加了lift-json_2.9.0-1-2.4.jar"到我的构建路径，我收到以下错误:

I have added "lift-json_2.9.0-1-2.4.jar " to my build path and I am getting following error:

找不到参数格式的隐含值:net.liftweb.json.Formats

could not find implicit value for parameter formats: net.liftweb.json.Formats

方法提取的参数不足:(隐式格式:net.liftweb.json.Formats，隐式 mf:scala.reflect.Manifest[MailServer])MailServer.未指定值参数格式，mf

not enough arguments for method extract: (implicit formats: net.liftweb.json.Formats, implicit mf: scala.reflect.Manifest[MailServer])MailServer. Unspecified value parameters formats, mf

推荐答案

您的示例适用于 Scala 2.11.7 和 lift-json-2.6.2.你用的是什么版本的scala?从您上面给出的 jar 的名称来看，您应该使用 scala 2.9.* ，它已经很老了.如果您不在 Scala 2.9.* 上，我想这是因为 Scala 版本之间的二进制不兼容.如果您使用 sbt，请尝试以下 build.sbt:

Your example works for me on scala 2.11.7 and lift-json-2.6.2. What version of scala are you using? From the name of the jar you gave above you should be using scala 2.9.* which is pretty old. If you're not on scala 2.9.* I guess it is because of binary incompatibilities between the Scala versions. If you are using sbt, try the following as build.sbt:

name := "<name of your project>"

scalaVersion := "2.11.7"

libraryDependencies += "net.liftweb" %% "lift-json" % "2.6.2"

然后您可以删除旧的 jar 文件，因为 sbt 会为您处理.

You can then remove the old jar file because sbt takes care of that for you.

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