rocketmq学习笔记 二 官方实例

学习rocketmq的时候，官方实例中有一些 operation

就是将命令行输入的参数，转化为java程序的入参 

其实很有意思的，咱们看下option的构造参数

public Option(String opt, String longOpt, boolean hasArg, String description)
        throws IllegalArgumentException
    {
        argName = "arg";
        numberOfArgs = -1;
        values = new ArrayList();
        OptionValidator.validateOption(opt);
        this.opt = opt;
        this.longOpt = longOpt;
        if(hasArg)
            numberOfArgs = 1;
        this.description = description;
    }

 public static CommandLine buildCommandline(String[] args) {
        final Options options = new Options();
        // ////////////////////////////////////////////////////
        Option opt = new Option("h", "help", false, "Print help");
        opt.setRequired(false);
        options.addOption(opt);

        opt = new Option("g", "consumerGroup", true, "Consumer Group Name");
        opt.setRequired(true);
        options.addOption(opt);

        opt = new Option("t", "topic", true, "Topic Name");
        opt.setRequired(true);
        options.addOption(opt);

        opt = new Option("s", "subscription", true, "subscription");
        opt.setRequired(false);
        options.addOption(opt);

        opt = new Option("f", "returnFailedHalf", true, "return failed result, for half message");
        opt.setRequired(true);
        options.addOption(opt);

        // ////////////////////////////////////////////////////

        PosixParser parser = new PosixParser();
        HelpFormatter hf = new HelpFormatter();
        hf.setWidth(110);
        CommandLine commandLine = null;
        try {
            commandLine = parser.parse(options, args);
            if (commandLine.hasOption('h')) {
                hf.printHelp("producer", options, true);
                return null;
            }
        } catch (ParseException e) {
            hf.printHelp("producer", options, true);
            return null;
        }

        return commandLine;
    }