hbase关于mapreduce读取写入
package cn.luxh.app;import java.io.IOException;import java.util.StringTokenizer;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.hbase.HBaseConfiguration;import org.apache.hadoop.hbase.client.Put;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.mapreduce.TableReducer;import org.apache.hadoop.hbase.util.Bytes;import org.apache.hadoop.io.IntWritable;import org.apache.hadoop.io.Text;import org.apache.hadoop.mapreduce.Job;/** * @author Luxh * */public class WordStat { /** * TableMapper<Text,IntWritable> Text:输出的key类型，IntWritable：输出的value类型 */ public static class MyMapper extends TableMapper<Text,IntWritable>{ private static IntWritable one = new IntWritable(1); private static Text word = new Text(); @Override protected void map(ImmutableBytesWritable key, Result value, Context context) throws IOException, InterruptedException { //表里面只有一个列族，所以我就直接获取每一行的值 String words = Bytes.toString(value.list().get(0).getValue()); StringTokenizer st = new StringTokenizer(words); while (st.hasMoreTokens()) { String s = st.nextToken(); word.set(s); context.write(word, one); } } } /** * TableReducer<Text,IntWritable> Text:输入的key类型，IntWritable：输入的value类型，ImmutableBytesWritable：输出类型 */ public static class MyReducer extends TableReducer<Text,IntWritable,ImmutableBytesWritable>{ @Override protected void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException { int sum = 0; for(IntWritable val:values) { sum+=val.get(); } //添加一行记录，每一个单词作为行键 Put put = new Put(Bytes.toBytes(key.toString())); //在列族result中添加一个标识符num,赋值为每个单词出现的次数 //String.valueOf(sum)先将数字转化为字符串，否则存到数据库后会变成\x00\x00\x00\x这种形式 //然后再转二进制存到hbase。 put.add(Bytes.toBytes("result"), Bytes.toBytes("num"), Bytes.toBytes(String.valueOf(sum))); context.write(new ImmutableBytesWritable(Bytes.toBytes(key.toString())),put); } } public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException { Configuration conf = HBaseConfiguration.create(); Job job = new Job(conf,"wordstat"); job.setJarByClass(Blog.class); Scan scan = new Scan(); //指定要查询的列族 scan.addColumn(Bytes.toBytes("content"),null); //指定Mapper读取的表为word TableMapReduceUtil.initTableMapperJob("word", scan, MyMapper.class, Text.class, IntWritable.class, job); //指定Reducer写入的表为stat TableMapReduceUtil.initTableReducerJob("stat", MyReducer.class, job); System.exit(job.waitForCompletion(true)?0:1); }}
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