import org.apache.hadoop.tools.TableListing; //导入依赖的package包/类
private int listSpanReceivers(List<String> args) throws IOException {
  SpanReceiverInfo infos[] = remote.listSpanReceivers();
  if (infos.length == 0) {
    System.out.println("[no span receivers found]");
    return 0;
  }
  TableListing listing = new TableListing.Builder().
      addField("ID").
      addField("CLASS").
      showHeaders().
      build();
  for (SpanReceiverInfo info : infos) {
    listing.addRow("" + info.getId(), info.getClassName());
  }
  System.out.println(listing.toString());
  return 0;
}
 

import org.apache.hadoop.tools.TableListing; //导入依赖的package包/类
@Override
public int run(Configuration conf, List<String> args) throws IOException {
  if (!args.isEmpty()) {
    System.err.println("Can't understand argument: " + args.get(0));
    return 1;
  }

  final DistributedFileSystem dfs = AdminHelper.getDFS(conf);
  try {
    final TableListing listing = new TableListing.Builder()
      .addField("").addField("", true)
      .wrapWidth(AdminHelper.MAX_LINE_WIDTH).hideHeaders().build();
    final RemoteIterator<EncryptionZone> it = dfs.listEncryptionZones();
    while (it.hasNext()) {
      EncryptionZone ez = it.next();
      listing.addRow(ez.getPath(), ez.getKeyName());
    }
    System.out.println(listing.toString());
  } catch (IOException e) {
    System.err.println(prettifyException(e));
    return 2;
  }

  return 0;
}
 

import org.apache.hadoop.tools.TableListing; //导入依赖的package包/类
@Override
public String getLongUsage() {
  TableListing listing = AdminHelper.getOptionDescriptionListing();
  listing.addRow("<path>", "A path to cache. The path can be " +
      "a directory or a file.");
  listing.addRow("<pool-name>", "The pool to which the directive will be " +
      "added. You must have write permission on the cache pool "
      + "in order to add new directives.");
  listing.addRow("-force",
      "Skips checking of cache pool resource limits.");
  listing.addRow("<replication>", "The cache replication factor to use. " +
      "Defaults to 1.");
  listing.addRow("<time-to-live>", "How long the directive is " +
      "valid. Can be specified in minutes, hours, and days, e.g. " +
      "30m, 4h, 2d. Valid units are [smhd]." +
      " \"never\" indicates a directive that never expires." +
      " If unspecified, the directive never expires.");
  return getShortUsage() + "\n" +
    "Add a new cache directive.\n\n" +
    listing.toString();
}
 

import org.apache.hadoop.tools.TableListing; //导入依赖的package包/类
@Override
public int run(Configuration conf, List<String> args) throws IOException {
  if (!args.isEmpty()) {
    System.err.println("Can't understand argument: " + args.get(0));
    return 1;
  }

  final DistributedFileSystem dfs = getDFS(conf);
  try {
    final TableListing listing = new TableListing.Builder()
      .addField("").addField("", true)
      .wrapWidth(MAX_LINE_WIDTH).hideHeaders().build();
    final RemoteIterator<EncryptionZone> it = dfs.listEncryptionZones();
    while (it.hasNext()) {
      EncryptionZone ez = it.next();
      listing.addRow(ez.getPath(), ez.getKeyName());
    }
    System.out.println(listing.toString());
  } catch (IOException e) {
    System.err.println(prettifyException(e));
    return 2;
  }

  return 0;
}
 

import org.apache.hadoop.tools.TableListing; //导入依赖的package包/类
@Override
public String getLongUsage() {
  TableListing listing = getOptionDescriptionListing();
  listing.addRow("<path>", "A path to cache. The path can be " +
      "a directory or a file.");
  listing.addRow("<pool-name>", "The pool to which the directive will be " +
      "added. You must have write permission on the cache pool "
      + "in order to add new directives.");
  listing.addRow("-force",
      "Skips checking of cache pool resource limits.");
  listing.addRow("<replication>", "The cache replication factor to use. " +
      "Defaults to 1.");
  listing.addRow("<time-to-live>", "How long the directive is " +
      "valid. Can be specified in minutes, hours, and days, e.g. " +
      "30m, 4h, 2d. Valid units are [smhd]." +
      " \"never\" indicates a directive that never expires." +
      " If unspecified, the directive never expires.");
  return getShortUsage() + "\n" +
    "Add a new cache directive.\n\n" +
    listing.toString();
}
 

import org.apache.hadoop.tools.TableListing; //导入依赖的package包/类
@Override
public String getLongUsage() {
  final TableListing listing = AdminHelper.getOptionDescriptionListing();
  listing.addRow("<path>", "The path of the encryption zone to create. " +
    "It must be an empty directory.");
  listing.addRow("<keyName>", "Name of the key to use for the " +
      "encryption zone.");
  return getShortUsage() + "\n" +
    "Create a new encryption zone.\n\n" +
    listing.toString();
}
 

import org.apache.hadoop.tools.TableListing; //导入依赖的package包/类
@Override
public String getLongUsage() {
  final TableListing listing = AdminHelper.getOptionDescriptionListing();
  listing.addRow("<command-name>", "The command for which to get " +
      "detailed help. If no command is specified, print detailed help for " +
      "all commands");
  return getShortUsage() + "\n" +
      "Get detailed help about a command.\n\n" +
      listing.toString();
}
 

import org.apache.hadoop.tools.TableListing; //导入依赖的package包/类
@Override
public String getLongUsage() {
  final TableListing listing = AdminHelper.getOptionDescriptionListing();
  listing.addRow("<path>",
      "The path of the file/directory for getting the storage policy");
  return getShortUsage() + "\n" +
      "Get the storage policy of a file/directory.\n\n" +
      listing.toString();
}