import java.io.*;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.io.IOUtils;import org.apache.hadoop.io.compress.CompressionCodec;import org.apache.hadoop.io.compress.CompressionOutputStream;import org.apache.hadoop.io.compress.GzipCodec;import org.apache.hadoop.util.ReflectionUtils;public class TestBlock2 {		public static void main(String[] args) throws Exception {//		Configuration conf = new Configuration();//		Class
      codecClass = Class.forName("org.apache.hadoop.io.compress.GzipCodec");//		CompressionCodec codec = (CompressionCodec) ReflectionUtils.newInstance(codecClass, conf);		CompressionCodec codec = new GzipCodec();				InputStream in  = new FileInputStream(new File("a.txt"));				File fileOut = new File("a.txt"+codec.getDefaultExtension());		FileOutputStream outStream = new FileOutputStream(fileOut);				CompressionOutputStream out = codec.createOutputStream(outStream);				IOUtils.copyBytes(in, out, 4096, false);		in.close();//		out.close();		outStream.close();			}}

　　测试该代码的时候，犯了个基础的错误，在流的关闭上没有把最后引用的流关闭。

即 out.close(); 导致的问题就是压缩流 CompressionOutputStream 没有把压缩的内容输出到文件中。

NOTE: 记得关闭相应的流。