json数据格式：

[{"studentName":"lily","studentAge":12},{"studentName":"lucy","studentAge":15}]

pom：

<dependency>
    <groupId>org.apache.spark</groupId>
    <artifactId>spark-core_2.11</artifactId>
    <version>2.2.1</version>
</dependency>
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.44</version>
</dependency>

val conf = new SparkConf().setMaster("local").setAppName("json test")
val sc = new SparkContext(conf)
val textFile = sc.textFile("f:/data/*.txt")
textFile.map(JSON.parseArray)  //解析为json数组
  .flatMap(_.toArray)　　//json数组转为java数组，通过flatmap拉平
  .map(_.asInstanceOf[JSONObject])　　//把每个对象转成jsonobject
  .map(x => (x.getString("studentName"), (x.getInteger("studentAge"), 1)))　　//通过jsonobject的方法处理数据

//方法二
val yiqings = JSON.parseArray(value.reduce(_ + _), classOf[自定义样例类]).toArray().toList.asInstanceOf[List[自定义样例类]]
//转换成RDD
val value1 = sc.makeRDD(yiqings)