Question

我正在使用Scala - 我使用JacksMapper它工作正常，这里是代码

import java.io.FileOutputStream
import java.io.ObjectOutputStream
import java.io.FileInputStream
import java.io.ObjectInputStream
import scala.util.Marshal
import java.io.ByteArrayOutputStream
import java.io.PrintWriter
import scala.util.parsing.json.JSONObject
import scala.util.parsing.json.JSON
import scala.util.parsing.json.JSONArray
import java.util.concurrent.atomic.AtomicReference
import scala.collection.mutable._
//import com.lambdaworks.jacks.JacksMapper
import java.io.BufferedReader
import java.io.FileReader
import net.liftweb.json._
import net.liftweb.json.JsonDSL._

import net.liftweb.json.JsonAST._
import net.liftweb.json.Extraction._
import net.liftweb.json.Printer._

//import com.codahale.jerkson.Json._

object jsonTest extends Serializable{

  def main(args: Array[String]): Unit = {

    var i = 1
    val map = new HashMap[String, Any]() with scala.collection.mutable.SynchronizedMap[String, Any]

    while(i < 10000)
    {

    var in_list = List[Any]()
    in_list :+= "dummy"
    in_list :+= "dummy"
    in_list :+= "dummy"

    val in_map = HashMap[String,Any]()
    in_map("dummy"+i) = in_list

    var out_list = List[Any]()
    out_list :+= "cat1" 
    out_list :+= "hash1"
    out_list :+= 100
    out_list :+= (System.currentTimeMillis()/1000).toInt
    out_list :+= in_map

    map("dummy"+i) = out_list
    i = i + 1
    }

    val json = JacksMapper.writeValueAsString[scala.collection.immutable.Map[String,Any]](map.toMap)



    Some(new PrintWriter("foo.txt")).foreach{p => p.write(json); p.close}
    val t1 = System.currentTimeMillis()

    val br : BufferedReader = new BufferedReader(new FileReader("foo.txt"));
    val sb:StringBuilder = new StringBuilder();
      var line = br.readLine();

       while (line != null) {
           sb.append    (line);
           sb.append("\n");
           line = br.readLine();
       }
       val content = sb.toString();
       br.close()

       println(content.length())

    val obj = JacksMapper.readValue[scala.collection.immutable.Map[String,Any]](content)
       val obj = scala.collection.immutable.Map[String,Any]
    println(obj("dummy3"))
    println(System.currentTimeMillis() - t1)


  }

  }

但我正在尝试使用Lift_Json进行scala。请告诉我如何使用Lift_Json标签更改上述代码我得到了Lift_Json的Jar文件，并使用简单的解析，如compact（render（json））。

Answer 1

这样的事情应该能够完成你想要做的事情。它将生成您的测试Map，然后将其序列化为JSON字符串并将其写入文件。下一步将重新读取并将其提取到您可以读取的地图 - 如上例所示。

import net.liftweb.json._
import java.io._

implicit val formats = net.liftweb.json.DefaultFormats

val map = {
  val mb = new scala.collection.mutable.HashMap[String, Any]()
  (1 to 10000).foreach { i =>
    val in_list = "dummy" :: "dummy" :: "dummy" :: Nil
    val in_map = Map("dummy%s".format(i) -> in_list)
    mb += "dummy%s".format(i) -> List("cat1", "hash1", 100, (System.currentTimeMillis()/1000).toInt, in_map) 
  }
  mb.toMap
}

val json = Extraction.decompose(map)

val jsonStrOut = Printer.pretty(JsonAST.render(json))
val fileName = "foo.txt"

val fw = new FileWriter(fileName)
fw.write(jsonStrOut)
fw.close()

val jsonStrIn = scala.io.Source.fromFile(fileName).mkString

val obj = parse(jsonStrIn).asInstanceOf[JObject].values
println(obj("dummy3"))

虽然这是可行的，但我强烈建议利用case classes和其他Scala结构来帮助进行序列化和反序列化。 Lift非常善于处理这些对象。除非有理由在大地图中包含所有内容，否则我认为从长远来看，你会为自己省去很多麻烦。

在Scala中使用Lift-JSON将map转换为字符串

1 个答案: