如何使用Scala生成下面的Json对象结构：
{
"name": "flare",
"children": [{
"name": "analytics",
"children": [{
"name": "cluster",
"children": [{
"name": "AgglomerativeCluster",
"size": 3938
}, {
"name": "CommunityStructure",
"size": 3812
}, {
"name": "HierarchicalCluster",
"size": 6714
}, {
"name": "MergeEdge",
"size": 743
}]
}, {
"name": "graph",
"children": [{
"name": "BetweennessCentrality",
"size": 3534
}, {
"name": "LinkDistance",
"size": 5731
}, {
"name": "MaxFlowMinCut",
"size": 7840
}, {
"name": "ShortestPaths",
"size": 5914
}, {
"name": "SpanningTree",
"size": 3416
}]
}, {
"name": "optimization",
"children": [{
"name": "AspectRatioBanker",
"size": 7074
}]
}]
}, {
"name": "animate",
"children": [{
"name": "Easing",
"size": 17010
}, {
"name": "FunctionSequence",
"size": 5842
}, {
"name": "interpolate",
"children": [{
"name": "ArrayInterpolator",
"size": 1983
}, {
"name": "ColorInterpolator",
"size": 2047
}, {
"name": "DateInterpolator",
"size": 1375
}, {
"name": "Interpolator",
"size": 8746
}, {
"name": "MatrixInterpolator",
"size": 2202
}, {
"name": "NumberInterpolator",
"size": 1382
}, {
"name": "ObjectInterpolator",
"size": 1629
}, {
"name": "PointInterpolator",
"size": 1675
}, {
"name": "RectangleInterpolator",
"size": 2042
}]
}, {
"name": "ISchedulable",
"size": 1041
}, {
"name": "Parallel",
"size": 5176
}, {
"name": "Pause",
"size": 449
}, {
"name": "Scheduler",
"size": 5593
}, {
"name": "Sequence",
"size": 5534
}, {
"name": "Transition",
"size": 9201
}, {
"name": "Transitioner",
"size": 19975
}, {
"name": "TransitionEvent",
"size": 1116
}, {
"name": "Tween",
"size": 6006
}]
}, {
"name": "data",
"children": [{
"name": "converters",
"children": [{
"name": "Converters",
"size": 721
}, {
"name": "DelimitedTextConverter",
"size": 4294
}, {
"name": "GraphMLConverter",
"size": 9800
}, {
"name": "IDataConverter",
"size": 1314
}, {
"name": "JSONConverter",
"size": 2220
}]
}, {
"name": "DataField",
"size": 1759
}, {
"name": "DataSchema",
"size": 2165
}, {
"name": "DataSet",
"size": 586
}, {
"name": "DataSource",
"size": 3331
}, {
"name": "DataTable",
"size": 772
}, {
"name": "DataUtil",
"size": 3322
}]
}, {
"name": "display",
"children": [{
"name": "DirtySprite",
"size": 8833
}, {
"name": "LineSprite",
"size": 1732
}, {
"name": "RectSprite",
"size": 3623
}, {
"name": "TextSprite",
"size": 10066
}]
}, {
"name": "flex",
"children": [{
"name": "FlareVis",
"size": 4116
}]
}, {
"name": "physics",
"children": [{
"name": "DragForce",
"size": 1082
}, {
"name": "GravityForce",
"size": 1336
}, {
"name": "IForce",
"size": 319
}, {
"name": "NBodyForce",
"size": 10498
}, {
"name": "Particle",
"size": 2822
}, {
"name": "Simulation",
"size": 9983
}, {
"name": "Spring",
"size": 2213
}, {
"name": "SpringForce",
"size": 1681
}]
}]
};
}
这是我到目前为止所做的：
object DendorgramTORecursive {
def getObject = {
val topLevelNode = new com.data.recursive.DendogramVO
topLevelNode.setName("flare")
val level1Node = new com.data.recursive.Children
level1Node.setName("analytics")
val level1NodeData = new java.util.ArrayList[com.data.recursive.Children]()
level1NodeData.add(level1Node);
level1Node.setChildren(level1NodeData)
//topLevelNode.setChildren(level1Node)
topLevelNode
}
}
package com.data.recursive;
import java.util.List;
public class DendogramVO {
private List<Children> children;
private String name;
public List<Children> getChildren() {
return this.children;
}
public void setChildren(List<Children> children) {
this.children = children;
}
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
}
package com.data.recursive;
import java.util.List;
public class Children {
private List<Children> children;
private String name;
public List<Children> getChildren() {
return children;
}
public void setChildren(List<Children> children) {
this.children = children;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
返回json：
"{"children":[{"children":[{"name":"cluster","children":[{"name":"AgglomerativeCluster","size":3938},{"name":"TestCLuster","size":3938}]}],"name":"analytics"}],"name":"flare"}"
这看起来很麻烦，我觉得应该有一个更干净的方法吗？
答案 0 :(得分：2)
建议你去coursera.org学习新课程：反应式编程原理。
在第一堂课中，有一个很好的Json演讲。
abstract class JSON
case class JSeq (elems: List[JSON]) extends JSON
case class JObj (bindings: Map[String, JSON]) extends JSON
case class JNum (num: Double) extends JSON
case class JStr (str: String) extends JSON
case class JBool(b: Boolean) extends JSON
case object JNull extends JSON
val data = JObj(Map(
”firstName” -> JStr(”John”),
”lastName” -> JStr(”Smith”),
”address” -> JObj(Map(
”streetAddress” -> JStr(”21 2nd Street”),
”state” -> JStr(”NY”),
”postalCode” -> JNum(10021)
)),
”phoneNumbers” -> JSeq(List(
JObj(Map(
”type” -> JStr(”home”), ”number” -> JStr(”212 555-1234”)
)),
JObj(Map(
”type” -> JStr(”fax”), ”number” -> JStr(”646 555-4567”)
)) )) ))
def show(json: JSON): String = json match {
case JSeq(elems) =>
”[” + (elems map show mkString ”, ”) + ”]”
case JObj(bindings) =>
val assocs = bindings map {
case (key, value) => ”\”” + key + ”\”: ” + show(value)
}
”{” + (assocs mkString ”, ”) + ”}”
case JNum(num) => num.toString
case JStr(str) => ’\”’ + str + ’\”’
case JBool(b) => b.toString
case JNull => ”null”
}
答案 1 :(得分：1)
使用JSON4S，您可以使用简单的案例类：
case class Node(name: String, children: Option[List[Node]], size: Option[Int])
以下是如何构建Node个对象的树并打印生成的JSON：
object WriteJson extends App {
import org.json4s.DefaultFormats
import org.json4s.native.Serialization.{write, writePretty}
val node1 = Node("AgglomerativeCluster", None, Some(3938))
val node2 = Node("cluster", Some(List(node1)), None)
val node3 = Node("analytics", Some(List(node2)), None)
val node4 = Node("flare", Some(List(node3)), None)
implicit val formats = DefaultFormats
println(writePretty(node4))
}
这就是你读JSON的方法：
object ReadJson extends App {
import org.json4s._
import org.json4s.native.JsonMethods._
val json =
"""
|{
| "name": "flare",
| "children": [
| {
| "name": "analytics",
| "children": [
| {
| "name": "cluster",
| "children": [
| {
| "name": "AgglomerativeCluster",
| "size": 3938
| }
| ]
| },
| ]
| }
| ]
|}
""".stripMargin
implicit val formats = DefaultFormats
val node = parse(json).extract[Node]
println(node) // Node(flare,Some(List(Node(analytics,Some(List(Node(cluster,Some(List(Node(AgglomerativeCluster,None,Some(3938)))),None))),None))),None)
}
Node类适用于所有值，因为两个不同的成员（children和size）都包含Option。您可以使用isDefined来确定某个值是否包含数据，例如node.children.isDefined。
答案 2 :(得分：0)
我使用Google GSON库以及我写的一些helper functions。它允许一些有点酷，几乎是文字的JSON语法，如下所示。
JSON(
"lis" -> List("", true, 2.0, 3L, JSON(), null),
"obj" -> JSON(
"nested_key" -> JSON()
)
)
答案 3 :(得分：0)
scala pickling将转换为JSON和从JSON转换。我认为这是一个Typesafe项目。
答案 4 :(得分：0)
使用Genson，您可以轻松地将scala Map / Seq或case类映射到Json并返回。
import com.owlike.genson.defaultGenson_
val json = toJson(Map("name" -> "foo"))
val value = fromJson[Map[String, String](json)
此外，它可能更多的是品味问题，但Genson并没有像其他lib一样大量使用implicits。例如，您不会使用implicits配置它，而是使用更经典的构建器，使您的代码更具可读性。
import com.owlike.genson._
object CustomGenson {
lazy val customGenson = new ScalaGenson(
new GensonBuilder()
.useIndentation(true)
.useDateAsTimestamp(true)
.withBundle(new JodaTimeBundle())
.create()
)
}
// then just import it in the places you want to use this instance instead of the default one
import CustomGenson.customGenson._