1. 上传数据到hdfs中
2. 写Map\Reduce过程
3. 输出结果到hbase中
Tips:
1. 因为map是从hdfs中取数据,因此没有太大变化;而reduce需要输出结果到hbase中,所以这里继承了TableReduce<keyin,valuein,keyout>,这里没有valueout,但是规定TableReduce的valueout必须是Put或者Delete实例。
2. 已经确定了输入输出路径,所以不用在eclipse中配置Run Configuration了。
import java.io.IOException;
import java.util.StringTokenizer;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.client.HBaseAdmin;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.mapreduce.TableOutputFormat;
import org.apache.hadoop.hbase.mapreduce.TableReducer;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
public class WordCountHBase {
/**
* @param args
* @throws IOException
* @throws ClassNotFoundException
* @throws InterruptedException
*/
public static void main(String[] args) throws IOException, InterruptedException, ClassNotFoundException {
// TODO Auto-generated method stub
String tablename = "wordcount";
Configuration conf = new Configuration();
conf.set(TableOutputFormat.OUTPUT_TABLE, tablename);
createHBaseTable(tablename);
Job job = new Job(conf,"WordCount table");
job.setJarByClass(WordCountHBase.class);
job.setNumReduceTasks(3);
job.setMapperClass(Map.class);
job.setReducerClass(Reduce.class);
job.setMapOutputKeyClass(Text.class);
job.setMapOutputValueClass(IntWritable.class);
job.setInputFormatClass(TextInputFormat.class);
job.setOutputFormatClass(TableOutputFormat.class);
// 设置输入目录
FileInputFormat.addInputPath(job, new Path("hdfs://master:9000/input/wordcount/*"));
System.exit(job.waitForCompletion(true)0:1);
}
public static class Map extends Mapper<LongWritable, Text, Text, IntWritable> {
private final static IntWritable one = new IntWritable(1);
private Text text = new Text();
@Override
public void map(LongWritable key, Text value, Context context) throws IOException,InterruptedException{
String s = value.toString();
StringTokenizer st = new StringTokenizer(s);
while(st.hasMoreTokens()) {
text.set(st.nextToken());
context.write(text, one);
}
}
}
public static class Reduce extends TableReducer<Text, IntWritable, NullWritable> {
@Override
public void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException,InterruptedException{
int sum = 0;
for(IntWritable i:values) {
sum+=i.get();
}
Put put = new Put(Bytes.toBytes(key.toString()));
// row,columnFamily:column,value = word,content:count,sum
put.add(Bytes.toBytes("content"),Bytes.toBytes("count"),Bytes.toBytes(String.valueOf(sum)));
context.write(NullWritable.get(), put);
}
}
/**
* create a table
* @param tablename
* @throws IOException
*/
public static void createHBaseTable(String tablename) throws IOException {
HTableDescriptor htd = new HTableDescriptor(tablename);
HColumnDescriptor col = new HColumnDescriptor("content");
htd.addFamily(col);
Configuration cfg = HBaseConfiguration.create();
HBaseAdmin admin = new HBaseAdmin(cfg);
if(admin.tableExists(tablename)) {
System.out.println("table exists,trying recreate table!");
admin.disableTable(tablename);
admin.deleteTable(tablename);
admin.createTable(htd);
}
else {
System.out.println("create new table:"+tablename);
admin.createTable(htd);
}
}
}
结果: