使用Hadoop API 解压缩 HDFS文件

　　压缩完了，当然需要解压缩了。

　　直接上代码：

private static void getFile(String filePath) throws IOException, ClassNotFoundException {

        FileSystem fs = FileSystem.get(URI.create(filePath), HDFSConf.getConf());
        Path path = new Path(filePath);
        if (fs.exists(path) ) {


            FSDataInputStream in;
            FSDataOutputStream out;
            Path outPath;

            FileStatus file = fs.getFileStatus(path);
            // 该压缩方法对应的文件扩展名

            outPath = new Path(filePath.substring(0,filePath.indexOf(".")) + ".new");
            logger.info("out put path is : " + outPath.toString());

            if (fs.createNewFile(outPath)) {

                CompressionCodecFactory factory = new CompressionCodecFactory(HDFSConf.getConf());
                CompressionCodec codec = factory.getCodec(file.getPath());
                in = fs.open(file.getPath());
                InputStream cin = codec.createInputStream(in);
                logger.info("create file  : " + outPath.toString());

                out = fs.append(outPath);

                // 缓冲区设为5MB
                IOUtils.copyBytes(cin, out, 1024 * 1024 * 5, false);

                out.flush();
                cin.close();
                in.close();
                out.close();


                logger.info("Decompress file successful");
            } else {
                logger.error("File exists");
            }


        } else {
            logger.info("There is no file :" + filePath);
        }

    }

打包执行：　　

[hadoop@venn05 venn]$ java -cp compressHdfsFile-1.0-SNAPSHOT.jar com.utstarcom.hdfs.DeCompressFile /aaa/test/viewlog_20180402.log.gz
2018-06-10 04:21:44.562 [Common.java] [main] 
INFO : start init : 
2018-06-10 04:21:44.566 [Common.java] [main] 
INFO : properties path : /opt/hadoop/tmp/venn/
/opt/hadoop/tmp/venn/hdfs.properties
default.compress.format
hdfs.uri
2018-06-10 04:21:44.568 [Common.java] [main] 
INFO : get System enviroment : 46
2018-06-10 04:21:44.569 [Common.java] [main] 
INFO : properties path : {hdfs.uri=hdfs://venn06:8020, default.compress.format=bz2}
hdfs://venn06:8020/aaa/test/viewlog_20180402.log.gz
log4j:WARN No appenders could be found for logger (org.apache.hadoop.util.Shell).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
2018-06-10 04:21:46.409 [DeCompressFile.java] [main] 
INFO : out put path is : hdfs://venn06:8020/aaa/test/viewlog_20180402.new
2018-06-10 04:21:46.623 [DeCompressFile.java] [main] 
INFO : create file : hdfs://venn06:8020/aaa/test/viewlog_20180402.new
2018-06-10 04:22:24.566 [DeCompressFile.java] [main] 
INFO : Decompress file successful
cost : 
39 s

　文件大小： 249.4 M ，解压后大小：1.4 G，执行时间 39 s，很不错

文件大小：
[hadoop@ut01 venn]$ hadoop fs -ls /aaa/test/
18/06/10 04:26:29 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Found 3 items
-rw-r--r-- 3 hadoop supergroup 1515343101 2018-06-03 17:07 /aaa/test/viewlog_20180402.log
-rw-r--r-- 3 hadoop supergroup 261506977 2018-06-09 15:46 /aaa/test/viewlog_20180402.log.gz
-rw-r--r-- 3 hadoop supergroup 1515343101 2018-06-09 15:43 /aaa/test/viewlog_20180402.new
[hadoop@ut01 venn]$ hadoop fs -ls -h /aaa/test/
18/06/10 04:26:38 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Found 3 items
-rw-r--r-- 3 hadoop supergroup 1.4 G 2018-06-03 17:07 /aaa/test/viewlog_20180402.log
-rw-r--r-- 3 hadoop supergroup 249.4 M 2018-06-09 15:46 /aaa/test/viewlog_20180402.log.gz
-rw-r--r-- 3 hadoop supergroup 1.4 G 2018-06-09 15:43 /aaa/test/viewlog_20180402.new

　项目地址：码云