Java tutorial
/* This file is part of VoltDB. * Copyright (C) 2008-2012 VoltDB Inc. * * VoltDB is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * VoltDB is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with VoltDB. If not, see <http://www.gnu.org/licenses/>. */ package org.voltdb; import java.lang.annotation.ElementType; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.annotation.Target; import java.lang.reflect.Field; import java.util.Map; import java.util.Map.Entry; import java.util.TreeMap; import org.apache.commons.cli.CommandLine; import org.apache.commons.cli.CommandLineParser; import org.apache.commons.cli.HelpFormatter; import org.apache.commons.cli.Options; import org.apache.commons.cli.PosixParser; public abstract class CLIConfig { @Retention(RetentionPolicy.RUNTIME) // Make this annotation accessible at runtime via reflection. @Target({ ElementType.FIELD }) // This annotation can only be applied to class methods. public @interface Option { String opt() default ""; String shortOpt() default ""; boolean hasArg() default true; boolean required() default false; String desc() default ""; } @Retention(RetentionPolicy.RUNTIME) // Make this annotation accessible at runtime via reflection. @Target({ ElementType.FIELD }) // This annotation can only be applied to class methods. public @interface AdditionalArgs { String opt() default ""; boolean hasArg() default false; boolean required() default false; String desc() default ""; } // Apache Commons CLI API - requires JAR protected final Options options = new Options(); protected Options helpmsgs = new Options(); protected String cmdName = "command"; protected String configDump; protected String usage; public void exitWithMessageAndUsage(String msg) { System.err.println(msg); printUsage(); System.exit(-1); } public void printUsage() { // automatically generate the help statement HelpFormatter formatter = new HelpFormatter(); formatter.printHelp(cmdName, helpmsgs, false); } private void assignValueToField(Field field, String value) throws Exception { if ((value == null) || (value.length() == 0)) { return; } field.setAccessible(true); Class<?> cls = field.getType(); if ((cls == boolean.class) || (cls == Boolean.class)) field.set(this, Boolean.parseBoolean(value)); else if ((cls == byte.class) || (cls == Byte.class)) field.set(this, Byte.parseByte(value)); else if ((cls == short.class) || (cls == Short.class)) field.set(this, Short.parseShort(value)); else if ((cls == int.class) || (cls == Integer.class)) field.set(this, Integer.parseInt(value)); else if ((cls == long.class) || (cls == Long.class)) field.set(this, Long.parseLong(value)); else if ((cls == float.class) || (cls == Float.class)) field.set(this, Float.parseFloat(value)); else if ((cls == double.class) || (cls == Double.class)) field.set(this, Double.parseDouble(value)); else if ((cls == String.class)) field.set(this, value); else if (value.length() == 1 && ((cls == char.class) || (cls == Character.class))) field.set(this, value.charAt(0)); else { System.err.println( "Parsing failed. Reason: can not assign " + value + " to " + cls.toString() + " class"); printUsage(); System.exit(-1); } } public void parse(String cmdName, String[] args) { this.cmdName = cmdName; try { options.addOption("help", "h", false, "Print this message"); // add all of the declared options to the cli for (Field field : getClass().getDeclaredFields()) { if (field.isAnnotationPresent(Option.class)) { Option option = field.getAnnotation(Option.class); String opt = option.opt(); if ((opt == null) || (opt.trim().length() == 0)) { opt = field.getName(); } String shortopt = option.shortOpt(); if ((shortopt == null) || (shortopt.trim().length() == 0)) { options.addOption(null, opt, option.hasArg(), option.desc()); helpmsgs.addOption(null, opt, option.hasArg(), option.desc()); } else { options.addOption(shortopt, opt, option.hasArg(), option.desc()); helpmsgs.addOption(shortopt, opt, option.hasArg(), option.desc()); } } else if (field.isAnnotationPresent(AdditionalArgs.class)) { AdditionalArgs params = field.getAnnotation(AdditionalArgs.class); String opt = params.opt(); if ((opt == null) || (opt.trim().length() == 0)) { opt = field.getName(); } options.addOption(opt, params.hasArg(), params.desc()); } } CommandLineParser parser = new PosixParser(); CommandLine cmd = parser.parse(options, args); if (cmd.hasOption("help")) { printUsage(); System.exit(0); } String[] leftargs = cmd.getArgs(); int leftover = 0; // string key-value pairs Map<String, String> kvMap = new TreeMap<String, String>(); for (Field field : getClass().getDeclaredFields()) { if (field.isAnnotationPresent(Option.class)) { Option option = field.getAnnotation(Option.class); String opt = option.opt(); if ((opt == null) || (opt.trim().length() == 0)) { opt = field.getName(); } if (cmd.hasOption(opt)) { if (option.hasArg()) { assignValueToField(field, cmd.getOptionValue(opt)); } else { if (field.getType().equals(boolean.class) || field.getType().equals(Boolean.class)) { field.setAccessible(true); try { field.set(this, true); } catch (Exception e) { throw new IllegalArgumentException(e); } } else { printUsage(); } } } else { if (option.required()) { printUsage(); } } field.setAccessible(true); kvMap.put(opt, field.get(this).toString()); } else if (field.isAnnotationPresent(AdditionalArgs.class)) { // Deal with --table=BLHA, offer nice error message later leftover++; } } if (leftargs != null) { if (leftargs.length <= leftover) { Field[] fields = getClass().getDeclaredFields(); for (int i = 0, j = 0; i < leftargs.length; i++) { for (; j < fields.length; j++) { if (fields[j].isAnnotationPresent(AdditionalArgs.class)) break; } fields[j].setAccessible(true); fields[j].set(this, leftargs[i]); } } else { System.err.println("Expected " + leftover + " args, but receive " + leftargs.length + " args"); printUsage(); System.exit(-1); } } // check that the values read are valid // this code is specific to your app validate(); // build a debug string StringBuilder sb = new StringBuilder(); for (Entry<String, String> e : kvMap.entrySet()) { sb.append(e.getKey()).append(" = ").append(e.getValue()).append("\n"); } configDump = sb.toString(); } catch (Exception e) { System.err.println("Parsing failed. Reason: " + e.getMessage()); printUsage(); System.exit(-1); } } public void validate() { } public String getConfigDumpString() { return configDump; } }