sparksql分組後topN（JAVA）

<!-- spark -->
<dependency>
    <groupId>org.apache.spark</groupId>
    <artifactId>spark-core_2.10</artifactId>
    <version>1.6.0</version>
</dependency>
<dependency>
    <groupId>org.apache.spark</groupId>
    <artifactId>spark-sql_2.10</artifactId>
    <version>1.6.0</version>
</dependency>
<dependency>
    <groupId>org.apache.spark</groupId>
    <artifactId>spark-hive_2.10</artifactId>
    <version>1.6.0</version>
</dependency>

public class RowNumberTopN {
    public static void main(String[] args) {
        SparkConf conf = new SparkConf().setAppName("RowNumberTopN").setMaster("local");

        JavaSparkContext sc = new JavaSparkContext(conf);
        HiveContext hiveContext = new HiveContext(sc.sc());
        hiveContext.sql("drop table if exists sales");
        //創建銷售表
        hiveContext.sql("create table if not exists sales(product STRING,category STRING,revenue BIGINT)");
        hiveContext.sql("LOAD DATA LOCAL INPATH '/user/local/spark/resources/sales.txt' INTO TABLE sales");
        //進行row_number分組
        DataFrame topnDF = hiveContext.sql("SELECT product,category,revenue FROM (\n" +
                "SELECT product,category,revenue,row_number() OVER (PARTITION BY category ORDER BY revenue DESC) rank\n" +
                "FROM sales\n" +
                ") topn_sales where rank<=3");
        hiveContext.sql("drop table if exists top3_sales");
        topnDF.saveAsTable("top3_sales");
        sc.close();
    }
}