alluxio.shell.command.HelpCommand.java Source code

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Here is the source code for alluxio.shell.command.HelpCommand.java

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/*
 * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
 * (the "License"). You may not use this work except in compliance with the License, which is
 * available at www.apache.org/licenses/LICENSE-2.0
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied, as more fully set forth in the License.
 *
 * See the NOTICE file distributed with this work for information regarding copyright ownership.
 */

package alluxio.shell.command;

import alluxio.client.file.FileSystem;
import alluxio.exception.AlluxioException;
import alluxio.shell.AlluxioShellUtils;

import org.apache.commons.cli.CommandLine;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.SortedSet;
import java.util.TreeSet;

import javax.annotation.concurrent.ThreadSafe;

/**
 * Command for print help message for the given command. If there isn't given command, print help
 * messages for all supported commands.
 */
@ThreadSafe
public final class HelpCommand extends AbstractShellCommand {

    /**
     * @param fs the filesystem of Alluxio
     */
    public HelpCommand(FileSystem fs) {
        super(fs);
    }

    @Override
    public String getCommandName() {
        return "help";
    }

    private final Map<String, ShellCommand> mCommands = new HashMap<>();

    @Override
    public int run(CommandLine cl) throws AlluxioException, IOException {
        String[] args = cl.getArgs();
        SortedSet<String> sortedCmds = null;
        AlluxioShellUtils.loadCommands(mFileSystem, mCommands);
        if (args.length == 0) {
            // print help messages for all supported commands.
            sortedCmds = new TreeSet<>(mCommands.keySet());
            for (String cmd : sortedCmds) {
                printCommandInfo(cmd);
            }
        } else if (mCommands.containsKey(args[0])) {
            printCommandInfo(args[0]);
        } else {
            System.out.println(args[0] + " is an unknown command.");
        }
        return 0;
    }

    private void printCommandInfo(String commandName) {
        System.out.format("%-60s%s%n", "       [" + mCommands.get(commandName).getUsage() + "]   ",
                mCommands.get(commandName).getDescription());
    }

    @Override
    public String getUsage() {
        return "help <command>";
    }

    @Override
    public String getDescription() {
        return "Prints help message for the given command. "
                + "If there isn't given command, prints help messages for all supported commands.";
    }

    @Override
    public boolean validateArgs(String... args) {
        boolean valid = args.length <= getNumOfArgs();
        if (!valid) {
            System.out.println(getCommandName() + " takes at most " + getNumOfArgs() + " arguments, " + " not "
                    + args.length + "\n");
        }
        return valid;
    }

    @Override
    protected int getNumOfArgs() {
        return 1;
    }

}