[SPARK-15031][EXAMPLE] Use SparkSession in examples

## What changes were proposed in this pull request?
Use `SparkSession` according to [SPARK-15031](https://issues.apache.org/jira/browse/SPARK-15031)

`MLLLIB` is not recommended to use now, so examples in `MLLIB` are ignored in this PR.
`StreamingContext` can not be directly obtained from `SparkSession`, so example in `Streaming` are ignored too.

cc andrewor14

## How was this patch tested?
manual tests with spark-submit

Author: Zheng RuiFeng <ruifengz@foxmail.com>

Closes #13164 from zhengruifeng/use_sparksession_ii.

1 files changed, 7 insertions, 4 deletions

diff --git a/examples/src/main/python/pagerank.py b/examples/src/main/python/pagerank.py
index 2fdc9773d4..a399a9c37c 100755
--- a/examples/src/main/python/pagerank.py
+++ b/examples/src/main/python/pagerank.py
@@ -25,7 +25,7 @@ import re
 import sys
 from operator import add
 
-from pyspark import SparkContext
+from pyspark.sql import SparkSession
 
 
 def computeContribs(urls, rank):
@@ -51,14 +51,17 @@ if __name__ == "__main__":
           file=sys.stderr)
 
     # Initialize the spark context.
-    sc = SparkContext(appName="PythonPageRank")
+    spark = SparkSession\
+        .builder\
+        .appName("PythonPageRank")\
+        .getOrCreate()
 
     # Loads in input file. It should be in format of:
     #     URL         neighbor URL
     #     URL         neighbor URL
     #     URL         neighbor URL
     #     ...
-    lines = sc.textFile(sys.argv[1], 1)
+    lines = spark.read.text(sys.argv[1]).rdd.map(lambda r: r[0])
 
     # Loads all URLs from input file and initialize their neighbors.
     links = lines.map(lambda urls: parseNeighbors(urls)).distinct().groupByKey().cache()
@@ -79,4 +82,4 @@ if __name__ == "__main__":
     for (link, rank) in ranks.collect():
         print("%s has rank: %s." % (link, rank))
 
-    sc.stop()
+    spark.stop()