[SPARK-5090] [EXAMPLES] The improvement of python converter for hbase

Hi,

Following the discussion in http://apache-spark-developers-list.1001551.n3.nabble.com/python-converter-in-HBaseConverter-scala-spark-examples-td10001.html. I made some modification in three files in package examples:
1. HBaseConverters.scala: the new converter will converts all the records in an hbase results into a single string
2. hbase_input.py: as the value string may contain several records, we can use ast package to convert the string into dict
3. HBaseTest.scala: as the package examples use hbase 0.98.7 the original constructor HTableDescriptor is deprecated. The updation to new constructor is made

Author: GenTang <gen.tang86@gmail.com>

Closes #3920 from GenTang/master and squashes the following commits:

d2153df [GenTang] import JSONObject precisely
4802481 [GenTang] dump the result into a singl String
62df7f0 [GenTang] remove the comment
21de653 [GenTang] return the string in json format
15b1fe3 [GenTang] the modification of comments
5cbbcfc [GenTang] the improvement of pythonconverter
ceb31c5 [GenTang] the modification for adapting updation of hbase
3253b61 [GenTang] the modification accompanying the improvement of pythonconverter

examples/src/main/python/hbase_inputformat.py

@@ -18,6 +18,7 @@
 from __future__ import print_function
 
 import sys
+import json
 
 from pyspark import SparkContext
 
@@ -27,24 +28,24 @@ Create test data in HBase first:
 hbase(main):016:0> create 'test', 'f1'
 0 row(s) in 1.0430 seconds
 
-hbase(main):017:0> put 'test', 'row1', 'f1', 'value1'
+hbase(main):017:0> put 'test', 'row1', 'f1:a', 'value1'
 0 row(s) in 0.0130 seconds
 
-hbase(main):018:0> put 'test', 'row2', 'f1', 'value2'
+hbase(main):018:0> put 'test', 'row1', 'f1:b', 'value2'
 0 row(s) in 0.0030 seconds
 
-hbase(main):019:0> put 'test', 'row3', 'f1', 'value3'
+hbase(main):019:0> put 'test', 'row2', 'f1', 'value3'
 0 row(s) in 0.0050 seconds
 
-hbase(main):020:0> put 'test', 'row4', 'f1', 'value4'
+hbase(main):020:0> put 'test', 'row3', 'f1', 'value4'
 0 row(s) in 0.0110 seconds
 
 hbase(main):021:0> scan 'test'
 ROW                           COLUMN+CELL
- row1                         column=f1:, timestamp=1401883411986, value=value1
- row2                         column=f1:, timestamp=1401883415212, value=value2
- row3                         column=f1:, timestamp=1401883417858, value=value3
- row4                         column=f1:, timestamp=1401883420805, value=value4
+ row1                         column=f1:a, timestamp=1401883411986, value=value1
+ row1                         column=f1:b, timestamp=1401883415212, value=value2
+ row2                         column=f1:, timestamp=1401883417858, value=value3
+ row3                         column=f1:, timestamp=1401883420805, value=value4
 4 row(s) in 0.0240 seconds
 """
 if __name__ == "__main__":
@@ -64,6 +65,8 @@ if __name__ == "__main__":
     table = sys.argv[2]
     sc = SparkContext(appName="HBaseInputFormat")
 
+    # Other options for configuring scan behavior are available. More information available at
+    # https://github.com/apache/hbase/blob/master/hbase-server/src/main/java/org/apache/hadoop/hbase/mapreduce/TableInputFormat.java
     conf = {"hbase.zookeeper.quorum": host, "hbase.mapreduce.inputtable": table}
     if len(sys.argv) > 3:
         conf = {"hbase.zookeeper.quorum": host, "zookeeper.znode.parent": sys.argv[3],
@@ -78,6 +81,8 @@ if __name__ == "__main__":
         keyConverter=keyConv,
         valueConverter=valueConv,
         conf=conf)
+    hbase_rdd = hbase_rdd.flatMapValues(lambda v: v.split("\n")).mapValues(json.loads)
+
     output = hbase_rdd.collect()
     for (k, v) in output:
         print((k, v))

examples/src/main/scala/org/apache/spark/examples/pythonconverters/HBaseConverters.scala

@@ -18,20 +18,34 @@
 package org.apache.spark.examples.pythonconverters
 
 import scala.collection.JavaConversions._
+import scala.util.parsing.json.JSONObject
 
 import org.apache.spark.api.python.Converter
 import org.apache.hadoop.hbase.client.{Put, Result}
 import org.apache.hadoop.hbase.io.ImmutableBytesWritable
 import org.apache.hadoop.hbase.util.Bytes
+import org.apache.hadoop.hbase.KeyValue.Type
+import org.apache.hadoop.hbase.CellUtil
 
 /**
- * Implementation of [[org.apache.spark.api.python.Converter]] that converts an
- * HBase Result to a String
+ * Implementation of [[org.apache.spark.api.python.Converter]] that converts all
+ * the records in an HBase Result to a String
  */
 class HBaseResultToStringConverter extends Converter[Any, String] {
   override def convert(obj: Any): String = {
+    import collection.JavaConverters._
     val result = obj.asInstanceOf[Result]
-    Bytes.toStringBinary(result.value())
+    val output = result.listCells.asScala.map(cell =>
+        Map(
+          "row" -> Bytes.toStringBinary(CellUtil.cloneRow(cell)),
+          "columnFamily" -> Bytes.toStringBinary(CellUtil.cloneFamily(cell)),
+          "qualifier" -> Bytes.toStringBinary(CellUtil.cloneQualifier(cell)),
+          "timestamp" -> cell.getTimestamp.toString,
+          "type" -> Type.codeToType(cell.getTypeByte).toString,
+          "value" -> Bytes.toStringBinary(CellUtil.cloneValue(cell))
+        )
+    )
+    output.map(JSONObject(_).toString()).mkString("\n")
   }
 }