hadoop学习笔记4：java实现hdfs -ls/-lsr

作业1：java代码实现hadoop fs -lsr的功能，调用FileSystem.listStatus(...)方法，显示结果，要求结果显示样式如hadoop fs -ls xxx的结果类似。

 

作业2：java 代码实现 hadoop fs -lsr 的功能

------上面两题的代码如下：

package hdfs;

import java.io.IOException;

import java.net.URI;

import java.net.URISyntaxException;

import org.apache.commons.lang.time.DateFormatUtils;

import org.apache.hadoop.conf.Configuration;

import org.apache.hadoop.fs.FileStatus;

import org.apache.hadoop.fs.FileSystem;

import org.apache.hadoop.fs.Path;

public class TestFIleSystem {

        public static void main(String[] args) throws IOException,

                     URISyntaxException {

               final FileSystem fs = FileSystem.get( new URI("hdfs://chaoren1:9012" ),

                            new Configuration());

               FileStatus[] listStatus = fs.listStatus( new Path("/" ));

               // java代码实现hadoop fs - lsr的功能，调用FileSystem.listStatus(...)方法，显示结果，要求结果显示样式如 hadoop fs -ls  xxx的结果类似。

               //ls (fs);

               // java 代码实现 hadoop fs - lsr 的功能

               lsr(fs, listStatus);

       }

        private static void lsr(FileSystem fs, FileStatus[] listStatus)

                      throws IOException {

               for (FileStatus fileStatus : listStatus) {

                      // 判断是否是文件夹

                      final boolean isdir = fileStatus.isDir();

                      final String permission = fileStatus.getPermission().toString();

                      final short replication = fileStatus.getReplication();

                      final String group = fileStatus.getGroup().toString();

                      final String owner = fileStatus.getOwner().toString();

                      final long blockSize = fileStatus.getBlockSize();

                      final String modificationTime = DateFormatUtils.format (

                                  fileStatus.getModificationTime(), "yyyy-MM-dd HH:mm:ss");

                      final String path = fileStatus.getPath().toString();

                      final String substringPath = path.substring(20, path.length());

                     System. out.println((isdir ? "d" : "-" )+ permission + "  "

                                  + (replication > 0 ? replication : "-").toString() + " "

                                  + owner + " " + group + "  " + blockSize + "\t\t"

                                  + modificationTime + " " + substringPath);

                      if (isdir) {

                            lsr(fs, fs.listStatus(fileStatus.getPath()));

                     }

              }

       }

        private static void ls( final FileSystem fs) throws IOException {

               final FileStatus[] listStatus = fs.listStatus(new Path( "/"));

               for (FileStatus fileStatus : listStatus) {

                      // 判断是否是文件夹

                      final boolean isdir = fileStatus.isDir();

                      final String permission = fileStatus.getPermission().toString();

                      final short replication = fileStatus.getReplication();

                      final String group = fileStatus.getGroup().toString();

                      final String owner = fileStatus.getOwner().toString();

                      final long blockSize = fileStatus.getBlockSize();

                      final String modificationTime = DateFormatUtils.format (

                                  fileStatus.getModificationTime(), "yyyy-MM-dd HH:mm:ss");

                      final String path = fileStatus.getPath().toString();

                      final String substringPath = path.substring(20, path.length());

                     System. out.println((isdir ? "d" : "-" ) + permission + "  "

                                  + (replication > 0 ? replication : "-").toString() + " "

                                  + owner + " " + group + "  " + blockSize + "\t\t"

                                  + modificationTime + " " + substringPath);

              }

       }

}

作业3： 从NameNode的源代码中找到NameNode是一个RPC Server的证据

      (提示，只需要找到RPC.getServer的调用即可)