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陆续好多人会问，在写入Hbase的时候总是会出现空指针的问题，而检查程序，看起来一点也没有错。
如报的错误大致如下：
Error: application failed with exception
java.lang.RuntimeException: java.lang.NullPointerException
at org.apache.hadoop.hbase.client.RpcRetryingCaller.callWithoutRetries(RpcRetryingCaller.java:209)
at org.apache.hadoop.hbase.client.ClientScanner.call(ClientScanner.java:288)
at org.apache.hadoop.hbase.client.ClientScanner.nextScanner(ClientScanner.java:268)
at org.apache.hadoop.hbase.client.ClientScanner.initializeScannerInConstruction(ClientScanner.java:140)
at org.apache.hadoop.hbase.client.ClientScanner.<init>(ClientScanner.java:135)
at org.apache.hadoop.hbase.client.HTable.getScanner(HTable.java:802)
at org.apache.hadoop.hbase.client.MetaScanner.metaScan(MetaScanner.java:200)
at org.apache.hadoop.hbase.client.MetaScanner.metaScan(MetaScanner.java:85)
at org.apache.hadoop.hbase.client.MetaScanner.allTableRegions(MetaScanner.java:310)
at org.apache.hadoop.hbase.client.HTable.getRegionLocations(HTable.java:666)
at org.apache.hadoop.hbase.util.RegionSizeCalculator.<init>(RegionSizeCalculator.java:79)
at org.apache.hadoop.hbase.util.RegionSizeCalculator.<init>(RegionSizeCalculator.java:64)
at org.apache.hadoop.hbase.mapreduce.TableInputFormatBase.getSplits(TableInputFormatBase.java:160)
at org.apache.spark.rdd.NewHadoopRDD.getPartitions(NewHadoopRDD.scala:98)
at org.apache.spark.rdd.RDD$$anonfun$partitions$2.apply(RDD.scala:220)
at org.apache.spark.rdd.RDD$$anonfun$partitions$2.apply(RDD.scala:218)
at scala.Option.getOrElse(Option.scala:120)
at org.apache.spark.rdd.RDD.partitions(RDD.scala:218)
at org.apache.spark.SparkContext.runJob(SparkContext.scala:1335)
at org.apache.spark.rdd.RDD.count(RDD.scala:925)
at HBaseTest$.main(HBaseTest.scala:27)
at HBaseTest.main(HBaseTest.scala)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.apache.spark.deploy.SparkSubmit$.launch(SparkSubmit.scala:367)
at org.apache.spark.deploy.SparkSubmit$.main(SparkSubmit.scala:77)
at org.apache.spark.deploy.SparkSubmit.main(SparkSubmit.scala)
Caused by: java.lang.NullPointerException
at org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher.getMetaReplicaNodes(ZooKeeperWatcher.java:269)
at org.apache.hadoop.hbase.zookeeper.MetaRegionTracker.blockUntilAvailable(MetaRegionTracker.java:241)
at org.apache.hadoop.hbase.client.ZooKeeperRegistry.getMetaRegionLocation(ZooKeeperRegistry.java:62)
at org.apache.hadoop.hbase.client.ConnectionManager$HConnectionImplementation.locateMeta(ConnectionManager.java:1213)
at org.apache.hadoop.hbase.client.ConnectionManager$HConnectionImplementation.locateRegion(ConnectionManager.java:1174)
at org.apache.hadoop.hbase.client.RpcRetryingCallerWithReadReplicas.getRegionLocations(RpcRetryingCallerWithReadReplicas.java:294)
at org.apache.hadoop.hbase.client.ScannerCallableWithReplicas.call(ScannerCallableWithReplicas.java:130)
at org.apache.hadoop.hbase.client.ScannerCallableWithReplicas.call(ScannerCallableWithReplicas.java:55)
at org.apache.hadoop.hbase.client.RpcRetryingCaller.callWithoutRetries(RpcRetryingCaller.java:201)
... 28 more
今天就将这种问题解决方法写成博客，其实解决办法非常简单。其问题主要发生在这行代码当中。
hbaseContext.bulkPut[(Array[Byte], Array[(Array[Byte], Array[Byte], Array[Byte])])](rdd,
tableName,
(putRecord) => {
val put = new Put(putRecord._1)
putRecord._2.foreach((putValue) => put.add(putValue._1, putValue._2, putValue._3))
put
},
true);
}
这个问题，主要原因在于从HiveContext中访问的DataFrame中，遍历的某些行里面putRecord中的某一个单元值为NULL，所以就会抛出这种异常。
因此在put.add的时候首先需要进行判断一下。
如 putRecord.IsNullAt(index)，这样进行判断，如果为NULL值，简单设个特定的字符串，马上什么问题全部解决。
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