【大数据系列】基于MapReduce的数据处理 SequenceFile序列化文件

package com.slp;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.SequenceFile;
import org.apache.hadoop.io.SequenceFile.Reader;
import org.apache.hadoop.io.SequenceFile.Writer;
import org.apache.hadoop.io.Text;
import org.junit.Test;
public class TestSequenceFile {

@Test
public void write() throws IOException{
Configuration conf = new Configuration();
conf.set("fs.defaultFS", "hdfs://www.node1.com:9000/");
FileSystem fs  = FileSystem.get(conf);
Path path = new Path("hdfs://www.node1.com:9000/home/hadoop/seq.seq");
Writer writer  = SequenceFile.createWriter(fs, conf, path, IntWritable.class, Text.class);
writer.append(new IntWritable(1), new Text("tom1"));
writer.append(new IntWritable(2), new Text("tom2"));
writer.append(new IntWritable(3), new Text("tom3"));
writer.append(new IntWritable(4), new Text("tom4"));
writer.close();
System.out.println("over");
}

@Test
public void readSeq() throws IOException{
Configuration conf = new Configuration();
conf.set("fs.defaultFS", "hdfs://www.node1.com:9000/");
FileSystem fs  = FileSystem.get(conf);
Path path = new Path("hdfs://www.node1.com:9000/home/hadoop/seq.seq");
Reader reader = new SequenceFile.Reader(fs, path, conf);
IntWritable key = new IntWritable();
Text value = new Text();
while(reader.next(key, value)){
System.out.println(key+"="+value);
}
reader.close();
}
}