write & read a sequence file（基于全新2.2.0API）

write & read a sequence file

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write & read a sequence file

 import java.io.IOException;

 import org.apache.hadoop.io.SequenceFile;
 import org.apache.hadoop.io.SequenceFile.Writer;
 import org.apache.hadoop.io.SequenceFile.Reader;
 import org.apache.hadoop.io.IntWritable;
 import org.apache.hadoop.io.Text;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.conf.Configuration;

 public class MySequenceFile {
   static private final String[] DATA =  {
       "this is the first",
       "this is the second",
       "this is the third",
       "this is the forth"
     };  

   public static void main(String[] args) throws IOException {
     Configuration conf = new Configuration();
     FileSystem fs = FileSystem.get(conf);
     Path path = new Path(args[0]);
     IntWritable key = new IntWritable();
     Text value = new Text();

     SequenceFile.Writer writer = null;

     writer = SequenceFile.createWriter(conf, Writer.file(path), Writer.keyClass(key.getClass()), Writer.valueClass(value.getClass()));
     for( int i = 0; i < 1000; i++ ) {
       key.set(i + 1);
       value.set(DATA[i % DATA.length]);
       writer.append(key,value);
     }
     writer.close();
     SequenceFile.Reader reader = new SequenceFile.Reader(conf, Reader.file(path));
     while( reader.next(key, value) ) {
       String syncSeen = reader.syncSeen() ? "*" : "#";
       System.err.println(key + "\t" + value + "\t" + reader.getPosition()+ "\t" + syncSeen);
     }
     reader.close();
   }
 }