hadoop - 从HBase提取数据时，在RDD中获取Null数据

Question

我需要使用Spark API从HBase提取数据，并像SparkSQL一样在数据顶部进行查询。

我所做的事情如下:

创建Spark conf对象

创建的HBase对象

编写JAVPairRDD以获取记录。

我的主要类(class)代码如下:

import java.io.Serializable;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.mapreduce.TableInputFormat;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.spark.api.java.JavaPairRDD;
import org.apache.spark.api.java.JavaRDD;
import org.apache.spark.api.java.JavaSparkContext;
import org.apache.spark.api.java.function.PairFunction;
import org.apache.spark.examples.sql.JavaSparkSQL;
import org.apache.spark.sql.DataFrame;
import org.apache.spark.sql.SQLContext;
import org.apache.spark.sql.hive.HiveContext;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.spark.api.java.function.Function;

import scala.Tuple2;

import com.lsr.LSRTar;
import com.lsr.utils.*;
import com.spark.hbase.TestData;

public class SparkSQLHBaseMain extends SparkJob implements Serializable{
    public static final String APPNAME = "Spark-SQL HBase Application";

    public static Logger logger = LoggerFactory.getLogger(SparkSQLHBaseMain.class);

    public static void main(String[] args) {
        logger.info("Calling method runJob()");
        new SparkSQLHBaseMain().runJob();
    }

    public void runJob() {
        final JavaSparkContext javaSparkContext = getSparkContext(APPNAME);
        logger.info("Spark Object created !!!");
        SQLContext sqlContext = new SQLContext(javaSparkContext);
        Configuration hbaseConfig = HBaseUtils.getHBaseConf();

        hbaseConfig.set(TableInputFormat.INPUT_TABLE, "emp");
        hbaseConfig.set(TableInputFormat.SCAN_COLUMN_FAMILY, "a"); // column family 
        hbaseConfig.set(TableInputFormat.SCAN_COLUMNS, "a:id a:name");

        JavaPairRDD<ImmutableBytesWritable, Result> hBaseRDD = 
                  javaSparkContext.newAPIHadoopRDD(hbaseConfig, TableInputFormat.class, ImmutableBytesWritable.class, Result.class);

        JavaRDD<TestData> rowPairRDD = hBaseRDD.map(new Function<Tuple2<ImmutableBytesWritable, Result>, TestData>() {
                    public TestData call(Tuple2<ImmutableBytesWritable, Result> entry) throws Exception {
                        TestData cd = new TestData();
                        Result r = entry._2;
                        String keyRow = Bytes.toString(r.getRow());
                        cd.setRowkey(keyRow);
                        cd.setId((String) Bytes.toString(r.getValue(Bytes.toBytes("a"), Bytes.toBytes("id"))));
                        cd.setName((String) Bytes.toString(r.getValue(Bytes.toBytes("a"), Bytes.toBytes("name"))));
                        return cd;
                    }
                });
        System.out.println("Result : \n"+"ID : "+rowPairRDD.id()+"Name : "+rowPairRDD.name());

        DataFrame dataFrame = sqlContext.createDataFrame(rowPairRDD, TestData.class);
        dataFrame.show();
        dataFrame.cache();
        dataFrame.repartition(100);
        dataFrame.printSchema();
    }

}

我的Bean类代码如下:

package com.spark.hbase;

import java.io.Serializable;

public class TestData extends java.lang.Object implements Serializable{
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    String keyRow;
    String id;
    String name;
    public void setRowkey(String keyRow) {
        this.keyRow = keyRow;
    }

    public void setId(String id) {
        this.id = id;
    }

    public void setName(String name) {
        this.name = name;
    }

}

低于异常:

17/01/18 12:28:54 INFO HBaseUtils: HBase is running !!!
HBase is running!
17/01/18 12:28:56 INFO MemoryStore: Block broadcast_0 stored as values in memory (estimated size 214.5 KB, free 214.5 KB)
17/01/18 12:28:57 INFO MemoryStore: Block broadcast_0_piece0 stored as bytes in memory (estimated size 25.0 KB, free 239.5 KB)
17/01/18 12:28:57 INFO BlockManagerInfo: Added broadcast_0_piece0 in memory on localhost:43929 (size: 25.0 KB, free: 257.8 MB)
17/01/18 12:28:57 INFO SparkContext: Created broadcast 0 from newAPIHadoopRDD at SparkSQLHBaseMain.java:49
Result : 
ID : 1Name : null
Exception in thread "main" java.lang.NullPointerException
    at org.spark-project.guava.reflect.TypeToken.method(TypeToken.java:465)
    at org.apache.spark.sql.catalyst.JavaTypeInference$$anonfun$2.apply(JavaTypeInference.scala:110)
    at org.apache.spark.sql.catalyst.JavaTypeInference$$anonfun$2.apply(JavaTypeInference.scala:109)
    at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:244)
    at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:244)
    at scala.collection.IndexedSeqOptimized$class.foreach(IndexedSeqOptimized.scala:33)
    at scala.collection.mutable.ArrayOps$ofRef.foreach(ArrayOps.scala:108)
    at scala.collection.TraversableLike$class.map(TraversableLike.scala:244)
    at scala.collection.mutable.ArrayOps$ofRef.map(ArrayOps.scala:108)
    at org.apache.spark.sql.catalyst.JavaTypeInference$.org$apache$spark$sql$catalyst$JavaTypeInference$$inferDataType(JavaTypeInference.scala:109)
    at org.apache.spark.sql.catalyst.JavaTypeInference$.inferDataType(JavaTypeInference.scala:54)
    at org.apache.spark.sql.SQLContext.getSchema(SQLContext.scala:941)
    at org.apache.spark.sql.SQLContext.createDataFrame(SQLContext.scala:572)
    at org.apache.spark.sql.SQLContext.createDataFrame(SQLContext.scala:591)
    at com.ril.jio.spark.sql.SparkSQLHBaseMain.runJob(SparkSQLHBaseMain.java:63)
    at com.ril.jio.spark.sql.SparkSQLHBaseMain.main(SparkSQLHBaseMain.java:35)

我的Spark＆HBase正常工作。

请帮助我解决此问题。

Answer 1

我认为您的代码应如下所示:(未测试)
rowPairRDD之后

JavaRDD<TestData> rowPairRDD = ....

使用 foreach()对RDD进行迭代以读取记录

rowPairRDD.foreach(new VoidFunction<TestData>() {
    public void call(TestData entry) {
        System.out.println("Result : ID : " + entry.id() + " Name : " + entry.name());
    }
}