spark-学习笔记--21 RDD 转换为 DataFrame--使用反射

 RDD 转换为  DataFrame--使用反射

 

 

 

	
	public static void main(String[] args) {
		
		SparkConf conf  = new SparkConf().setMaster("local").setAppName("PersonDataFrame");
		JavaSparkContext sc = new JavaSparkContext(conf);
		SQLContext sqlContext = new org.apache.spark.sql.SQLContext(sc);
		JavaRDD<String> textFile = sc.textFile("d://json.txt");
		JavaRDD<Person> mapPerson = textFile.map(new Function<String, Person>() {

			@Override
			public Person call(String arg0) throws Exception {
				
				Person p = JSONObject.parseObject(arg0, Person.class);
				
				return p;
			}
		});
		
		
		//使用反射
		//RDD 转换为 DataFrame
	       DataFrame schemaPeople = sqlContext.createDataFrame(mapPerson, Person.class);
		schemaPeople.show();
		
		//指定表名
		schemaPeople.registerTempTable("people");
		//使用sql操作
		DataFrame teenagers = sqlContext.sql("SELECT name FROM people WHERE age >= 25");
		teenagers.show();
		
	
		
	}