MapReduce操作Hbase史上最完整范例

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Hbase里的数据量一般都小不了，因此MapReduce跟Hbase就成了天然的好搭档。本文中，本博主将给出最详细的用MR读取Hbase中数据的实例。

1.ZK授权表

首先一点来说，Hbase是强依赖于ZK的。博主所在的team，就经常出现ZK连接数太多被打爆然后Hbase挂了的情况。一般在访问Hbase表之前，需要通过访问ZK得到授权：

    /*** 为hbase表授权。** @param tableConfigKey 任意一个字符串。* @param tableName 需要授权的表名, scan涉及到的表不需要额外授权。* @param job 相关job。* @throws IOException*/public static void initAuthentication(String tableConfigKey, String tableName, Job job) throws IOException {Configuration peerConf = job.getConfiguration();peerConf.set(tableConfigKey, tableName);ZKUtil.applyClusterKeyToConf(peerConf, tableName);if (User.isHBaseSecurityEnabled(peerConf)) {LOGGER.info("Obtaining remote user authentication token with table:{}", tableName);try {User.getCurrent().obtainAuthTokenForJob(peerConf, job);} catch (InterruptedException ex) {LOGGER.info("Interrupted obtaining remote user authentication token");LOGGER.error("Obtained remote user authentication token with table:{}, error:\n", tableName, ex);Thread.interrupted();}LOGGER.info("Obtained remote user authentication token with table:{}", tableName);}}

代码相对比较简单，都是Hbase与ZK提供的一些辅助工具类。不解释。

2.thrift对象转化

本例中操作的对象为XX表，Column Family为"P", Qualifer 为"P"与"C"，里面对应的value都是thrift对象。其中"P"对应的thrift对象为:

struct UserProfile {1: optional byte sex; 2: optional i32 age;3: optional string phoneBrand;4: optional string locationProvince;
}

"C"对应的thrift对象为:

struct UserClickInfo {1: required i32 totolAck;2: required i32 totalClick;3: optional map<i64, map<string, i32>> ackClick;
}

这个时候我们就需要经常将Bytes转化为thrift对象，通用的方法为：

    /*** convert byte array to thrift object.** @param <T> type of thrift object.* @param thriftObj an thrift object.* @return byte array if convert succeeded, <code>null</code> if convert failed.* @throws TException*/public static final <T extends TBase<T, ?>> T convertBytesToThriftObject(byte[] raw, T thriftObj) throws TException {if (ArrayUtils.isEmpty(raw)) {return null;}Validate.notNull(thriftObj, "thriftObj");TDeserializer serializer = new TDeserializer(new TBinaryProtocol.Factory());serializer.deserialize(thriftObj, raw);return thriftObj;}

3.Map阶段读取Hbase里的数据

在Map阶段对Hbase表扫描，得出数据

 //输出的KV均为Textstatic class ReadMapper extends TableMapper<Text,Text> {@Overrideprotected void map(ImmutableBytesWritable key, Result res, Context context) throws IOException,InterruptedException{String uuid = StringUtils.reverse(Bytes.toString(key.copyBytes()));if (res == null || res.isEmpty()) return;res.getFamilyMap(USER_FEATURE_COLUMN_FAMILY);for(KeyValue kv:res.list()) {String qualifier = Bytes.toString(kv.getQualifier());//String qualifier = kv.getKeyString();if(qualifier.equals("P")) {try {UserProfile userProfile = new UserProfile();convertBytesToThriftObject(kv.getValue(), userProfile);String profileRes = userProfile.getAge() + "," + userProfile.getSex() + ","+ userProfile.getPhoneBrand() + "," + userProfile.getLocationProvince();context.write(new Text(uuid),new Text(profileRes));} catch (Exception ex) {}}else if(qualifier.equals("C")) {UserClickInfo userClickInfo = new UserClickInfo();try {convertBytesToThriftObject(kv.getValue(), userClickInfo);Map<Long,Map<String,Integer>> resMap = userClickInfo.getAckClick();for(Map.Entry<Long,Map<String,Integer>> entry:resMap.entrySet()) {String appid = String.valueOf(entry.getKey());int click = entry.getValue().get("click");int ack = entry.getValue().get("ack");String all = appid + "," + String.valueOf(click) + "," + String.valueOf(ack);context.write(new Text(uuid),new Text(all));}int allClick = userClickInfo.getTotalClick();int allAck = userClickInfo.getTotolAck();String allNum = "999," + String.valueOf(allClick) + "," + String.valueOf(allAck);context.write(new Text(uuid),new Text(allNum));} catch (Exception ex) {}}}}}

4.run方法里配置相关驱动

run方法里需要配置一些相关的参数，保证任务的顺利进行。
其中，TableMapReduceUtil.addDependencyJars方法添加了完成任务一些必要的类。

    public int run(String[] args) throws Exception{Configuration conf = HBaseConfiguration.create();Job job = Job.getInstance(conf,"read_data_from_hbase");job.setJarByClass(ReadDataFromHbase.class);job.setMapOutputKeyClass(Text.class);job.setMapOutputValueClass(Text.class);job.setReducerClass(ReadReducer.class);job.setSpeculativeExecution(false);TableMapReduceUtil.addDependencyJars(job.getConfiguration(),StringUtils.class, TimeUtils.class, Util.class,CompressionCodec.class, TStructDescriptor.class, ObjectMapper.class, CompressionCodecName.class, BytesInput.class);Scan scan = new Scan();//对整个CF扫描scan.addFamily(USER_FEATURE_COLUMN_FAMILY);String table = "XXX";initAuthentication(table,table,job);TableMapReduceUtil.initTableMapperJob(table,scan,ReadMapper.class,Text.class,Text.class,job);String output = "";FileSystem.get(job.getConfiguration()).delete(new Path(output), true);FileOutputFormat.setOutputPath(job,new Path(output));return job.waitForCompletion(true) ? 0 : 1;}

5.完整的代码

package XXX.XXX.XXX.mr_job_and_tools.task;import com.twitter.elephantbird.thrift.TStructDescriptor;
import XXX.XXX.XXX.XXX.common.util.TimeUtils;
import XXX.XXX.XXX.thrift.UserClickInfo;
import XXX.XXX.XXX.thrift.UserProfile;
import org.apache.commons.lang.ArrayUtils;
import org.apache.commons.lang.Validate;
import org.apache.commons.lang3.StringUtils;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil;
import org.apache.hadoop.hbase.mapreduce.TableMapper;
import org.apache.hadoop.hbase.security.User;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.zookeeper.ZKUtil;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
import org.apache.parquet.bytes.BytesInput;
import org.apache.parquet.format.CompressionCodec;
import org.apache.parquet.format.Util;
import org.apache.parquet.hadoop.metadata.CompressionCodecName;
import org.apache.thrift.TBase;
import org.apache.thrift.TDeserializer;
import org.apache.thrift.TException;
import org.apache.thrift.protocol.TBinaryProtocol;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import shaded.parquet.org.codehaus.jackson.map.ObjectMapper;import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;/*** Created by WangLei on 17-3-13.*/
public class ReadDataFromHbase extends Configured implements Tool{private static final Logger LOGGER = LoggerFactory.getLogger(ReadDataFromHbase.class);public static final byte[] USER_FEATURE_COLUMN_FAMILY = Bytes.toBytes("P");/*** convert byte array to thrift object.** @param <T> type of thrift object.* @param thriftObj an thrift object.* @return byte array if convert succeeded, <code>null</code> if convert failed.* @throws TException*/public static final <T extends TBase<T, ?>> T convertBytesToThriftObject(byte[] raw, T thriftObj) throws TException {if (ArrayUtils.isEmpty(raw)) {return null;}Validate.notNull(thriftObj, "thriftObj");TDeserializer serializer = new TDeserializer(new TBinaryProtocol.Factory());serializer.deserialize(thriftObj, raw);return thriftObj;}/*** 为hbase表授权。** @param tableConfigKey 任意一个字符串。* @param tableName 需要授权的表名, scan涉及到的表不需要额外授权。* @param job 相关job。* @throws IOException*/public static void initAuthentication(String tableConfigKey, String tableName, Job job) throws IOException {Configuration peerConf = job.getConfiguration();peerConf.set(tableConfigKey, tableName);ZKUtil.applyClusterKeyToConf(peerConf, tableName);if (User.isHBaseSecurityEnabled(peerConf)) {LOGGER.info("Obtaining remote user authentication token with table:{}", tableName);try {User.getCurrent().obtainAuthTokenForJob(peerConf, job);} catch (InterruptedException ex) {LOGGER.info("Interrupted obtaining remote user authentication token");LOGGER.error("Obtained remote user authentication token with table:{}, error:\n", tableName, ex);Thread.interrupted();}LOGGER.info("Obtained remote user authentication token with table:{}", tableName);}}static class ReadMapper extends TableMapper<Text,Text> {@Overrideprotected void map(ImmutableBytesWritable key, Result res, Context context) throws IOException,InterruptedException{String uuid = StringUtils.reverse(Bytes.toString(key.copyBytes()));if (res == null || res.isEmpty()) return;res.getFamilyMap(USER_FEATURE_COLUMN_FAMILY);for(KeyValue kv:res.list()) {String qualifier = Bytes.toString(kv.getQualifier());//String qualifier = kv.getKeyString();if(qualifier.equals("P")) {try {UserProfile userProfile = new UserProfile();convertBytesToThriftObject(kv.getValue(), userProfile);String profileRes = userProfile.getAge() + "," + userProfile.getSex() + ","+ userProfile.getPhoneBrand() + "," + userProfile.getLocationProvince();context.write(new Text(uuid),new Text(profileRes));} catch (Exception ex) {}}else if(qualifier.equals("C")) {UserClickInfo userClickInfo = new UserClickInfo();try {convertBytesToThriftObject(kv.getValue(), userClickInfo);Map<Long,Map<String,Integer>> resMap = userClickInfo.getAckClick();for(Map.Entry<Long,Map<String,Integer>> entry:resMap.entrySet()) {String appid = String.valueOf(entry.getKey());int click = entry.getValue().get("click");int ack = entry.getValue().get("ack");String all = appid + "," + String.valueOf(click) + "," + String.valueOf(ack);context.write(new Text(uuid),new Text(all));}int allClick = userClickInfo.getTotalClick();int allAck = userClickInfo.getTotolAck();String allNum = "999," + String.valueOf(allClick) + "," + String.valueOf(allAck);context.write(new Text(uuid),new Text(allNum));} catch (Exception ex) {}}}}}static class ReadReducer extends Reducer<Text,Text,Text,Text> {@Overrideprotected void reduce(Text key, Iterable<Text> values, Context context) throws IOException,InterruptedException{List<String> resultList = new ArrayList<String>();for(Text each:values) {resultList.add(each.toString());}String res = StringUtils.join(resultList,":");context.write(key,new Text(res));}}@Overridepublic int run(String[] args) throws Exception{Configuration conf = HBaseConfiguration.create();Job job = Job.getInstance(conf,"read_data_from_hbase");job.setJarByClass(ReadDataFromHbase.class);job.setMapOutputKeyClass(Text.class);job.setMapOutputValueClass(Text.class);job.setReducerClass(ReadReducer.class);job.setSpeculativeExecution(false);TableMapReduceUtil.addDependencyJars(job.getConfiguration(),StringUtils.class, TimeUtils.class, Util.class,CompressionCodec.class, TStructDescriptor.class, ObjectMapper.class, CompressionCodecName.class, BytesInput.class);Scan scan = new Scan();//对整个CF扫描scan.addFamily(USER_FEATURE_COLUMN_FAMILY);String table = "XXX";initAuthentication(table,table,job);TableMapReduceUtil.initTableMapperJob(table,scan,ReadMapper.class,Text.class,Text.class,job);String output = "";FileSystem.get(job.getConfiguration()).delete(new Path(output), true);FileOutputFormat.setOutputPath(job,new Path(output));return job.waitForCompletion(true) ? 0 : 1;}public static void main(String[] args) throws Exception{System.exit(ToolRunner.run(new ReadDataFromHbase(),args));}
}

然后将代码打包，提交到集群上运行对应的shell脚本即可。

6.版本信息

本文中的代码，对应的hadoop版本为2.6,Hbase版本为0.98。