CommandLine 和 Options

用到的jar包

        <dependency>
            <groupId>commons-cli</groupId>
            <artifactId>commons-cli</artifactId>
            <version>1.3.1</version>
        </dependency>

Option 的格式

Option(String opt, String longOpt, boolean hasArg, String description)

选项名，选项全称，是否有参数（如果true时没有参数会抛异常），描述

例如：

new Option("h","help",false,"print help");

Option 合法性校验

OptionValidator.class

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.commons.cli;

/**
 * Validates an Option string.
 *
 * @version $Id: OptionValidator.java 1544819 2013-11-23 15:34:31Z tn $
 * @since 1.1
 */
final class OptionValidator
{
    /**
     * Validates whether <code>opt</code> is a permissible Option
     * shortOpt.  The rules that specify if the <code>opt</code>
     * is valid are:
     *
     * <ul>
     *  <li>a single character <code>opt</code> that is either
     *  ' '(special case), '?', '@' or a letter</li>
     *  <li>a multi character <code>opt</code> that only contains
     *  letters.</li>
     * </ul>
     * <p>
     * In case {@code opt} is {@code null} no further validation is performed.
     *
     * @param opt The option string to validate, may be null
     * @throws IllegalArgumentException if the Option is not valid.
     */
    static void validateOption(String opt) throws IllegalArgumentException
    {
        // if opt is NULL do not check further
        if (opt == null)
        {
            return;
        }
        
        // handle the single character opt
        if (opt.length() == 1)
        {
            char ch = opt.charAt(0);

            if (!isValidOpt(ch))
            {
                throw new IllegalArgumentException("Illegal option name '" + ch + "'");
            }
        }

        // handle the multi character opt
        else
        {
            for (char ch : opt.toCharArray())
            {
                if (!isValidChar(ch))
                {
                    throw new IllegalArgumentException("The option '" + opt + "' contains an illegal "
                                                       + "character : '" + ch + "'");
                }
            }
        }
    }

    /**
     * Returns whether the specified character is a valid Option.
     *
     * @param c the option to validate
     * @return true if <code>c</code> is a letter, '?' or '@', otherwise false.
     */
    private static boolean isValidOpt(char c)
    {
        return isValidChar(c) || c == '?' || c == '@';
    }

    /**
     * Returns whether the specified character is a valid character.
     *
     * @param c the character to validate
     * @return true if <code>c</code> is a letter.
     */
    private static boolean isValidChar(char c)
    {
        return Character.isJavaIdentifierPart(c);
    }
}

常见异常

• org.apache.commons.cli.UnrecognizedOptionException
• org.apache.commons.cli.MissingOptionException
• org.apache.commons.cli.MissingArgumentException

CommandLine commandLine = parser.parse(options, args);

如果args开启某option，但options中不包含时，未识别选项

如果args开启某option，该option已设置为包含参数，但args 中没有该option参数时，丢失参数

如果某option已设置为必须，但args中未开启该option是，丢失选项

小样

package cli;

import org.apache.commons.cli.CommandLine;
import org.apache.commons.cli.CommandLineParser;
import org.apache.commons.cli.DefaultParser;
import org.apache.commons.cli.Option;
import org.apache.commons.cli.Options;
import org.apache.commons.cli.ParseException;

public class TestCommandline {
    public static void main(String[] args) throws ParseException {
        Options options = new Options();
        Option opt = new Option("n", "namesrvAddr", true,
                "Name server address list, eg: 192.168.0.1:9876;192.168.0.2:9876");
        opt.setRequired(false);
        options.addOption(opt);

        CommandLineParser parser = new DefaultParser();
        CommandLine commandLine = parser.parse(options, args);

        String optNmae = "n";
        if (commandLine.hasOption(optNmae)) {
            System.out.println(commandLine.getOptionValue(optNmae));
            for (String s : commandLine.getOptionValues(optNmae)) {
                System.out.print(s+" ");
            }
        }
    }
}

入参：

-n 192.168.0.1:9876 -n 192.168.0.2:9876

结果：

192.168.0.1:9876
192.168.0.1:9876 192.168.0.2:9876

小结

必须由『-』开启选项，短横后面需合法，由空格（不限个数）区分选项和参数。

一个选项只能跟一个参数。

选项参数对之外的自动忽略。

两个相同的选项参数由左至右依次被设置到参数数组中。