Java tutorial
/* * 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.hadoop.hbase.util; import java.io.IOException; import java.util.Set; import java.util.TreeSet; import org.apache.commons.cli.BasicParser; 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.ParseException; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.classification.InterfaceAudience; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.hbase.HBaseConfiguration; import org.apache.hadoop.util.Tool; import org.apache.hadoop.util.ToolRunner; /** * Common base class used for HBase command-line tools. Simplifies workflow and * command-line argument parsing. */ @InterfaceAudience.Private public abstract class AbstractHBaseTool implements Tool { protected static final int EXIT_SUCCESS = 0; protected static final int EXIT_FAILURE = 1; private static final String SHORT_HELP_OPTION = "h"; private static final String LONG_HELP_OPTION = "help"; private static final Log LOG = LogFactory.getLog(AbstractHBaseTool.class); private final Options options = new Options(); protected Configuration conf = null; private static final Set<String> requiredOptions = new TreeSet<String>(); protected String[] cmdLineArgs = null; /** * Override this to add command-line options using {@link #addOptWithArg} * and similar methods. */ protected abstract void addOptions(); /** * This method is called to process the options after they have been parsed. */ protected abstract void processOptions(CommandLine cmd); /** The "main function" of the tool */ protected abstract int doWork() throws Exception; @Override public Configuration getConf() { return conf; } @Override public void setConf(Configuration conf) { this.conf = conf; } @Override public final int run(String[] args) throws IOException { if (conf == null) { LOG.error("Tool configuration is not initialized"); throw new NullPointerException("conf"); } CommandLine cmd; try { // parse the command line arguments cmd = parseArgs(args); cmdLineArgs = args; } catch (ParseException e) { LOG.error("Error when parsing command-line arguemnts", e); printUsage(); return EXIT_FAILURE; } if (cmd.hasOption(SHORT_HELP_OPTION) || cmd.hasOption(LONG_HELP_OPTION) || !sanityCheckOptions(cmd)) { printUsage(); return EXIT_FAILURE; } processOptions(cmd); int ret = EXIT_FAILURE; try { ret = doWork(); } catch (Exception e) { LOG.error("Error running command-line tool", e); return EXIT_FAILURE; } return ret; } private boolean sanityCheckOptions(CommandLine cmd) { boolean success = true; for (String reqOpt : requiredOptions) { if (!cmd.hasOption(reqOpt)) { LOG.error("Required option -" + reqOpt + " is missing"); success = false; } } return success; } protected CommandLine parseArgs(String[] args) throws ParseException { options.addOption(SHORT_HELP_OPTION, LONG_HELP_OPTION, false, "Show usage"); addOptions(); CommandLineParser parser = new BasicParser(); return parser.parse(options, args); } protected void printUsage() { HelpFormatter helpFormatter = new HelpFormatter(); helpFormatter.setWidth(80); String usageHeader = "Options:"; String usageFooter = ""; String usageStr = "bin/hbase " + getClass().getName() + " <options>"; helpFormatter.printHelp(usageStr, usageHeader, options, usageFooter); } protected void addRequiredOptWithArg(String opt, String description) { requiredOptions.add(opt); addOptWithArg(opt, description); } protected void addRequiredOptWithArg(String shortOpt, String longOpt, String description) { requiredOptions.add(longOpt); addOptWithArg(shortOpt, longOpt, description); } protected void addOptNoArg(String opt, String description) { options.addOption(opt, false, description); } protected void addOptNoArg(String shortOpt, String longOpt, String description) { options.addOption(shortOpt, longOpt, false, description); } protected void addOptWithArg(String opt, String description) { options.addOption(opt, true, description); } protected void addOptWithArg(String shortOpt, String longOpt, String description) { options.addOption(shortOpt, longOpt, true, description); } /** * Parse a number and enforce a range. */ public static long parseLong(String s, long minValue, long maxValue) { long l = Long.parseLong(s); if (l < minValue || l > maxValue) { throw new IllegalArgumentException( "The value " + l + " is out of range [" + minValue + ", " + maxValue + "]"); } return l; } public static int parseInt(String s, int minValue, int maxValue) { return (int) parseLong(s, minValue, maxValue); } /** Call this from the concrete tool class's main function. */ protected void doStaticMain(String args[]) { int ret; try { ret = ToolRunner.run(HBaseConfiguration.create(), this, args); } catch (Exception ex) { LOG.error("Error running command-line tool", ex); ret = EXIT_FAILURE; } System.exit(ret); } }