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.jxtadoop.util; import java.io.FileNotFoundException; import java.io.IOException; import java.io.PrintStream; import java.net.URI; import java.net.URL; import java.net.URLClassLoader; import org.apache.commons.cli.CommandLine; import org.apache.commons.cli.CommandLineParser; import org.apache.commons.cli.GnuParser; import org.apache.commons.cli.HelpFormatter; import org.apache.commons.cli.Option; import org.apache.commons.cli.OptionBuilder; 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.jxtadoop.conf.Configuration; import org.apache.jxtadoop.fs.FileSystem; import org.apache.jxtadoop.fs.Path; /** * <code>GenericOptionsParser</code> is a utility to parse command line * arguments generic to the Hadoop framework. * * <code>GenericOptionsParser</code> recognizes several standarad command * line arguments, enabling applications to easily specify a namenode, a * jobtracker, additional configuration resources etc. * * <h4 id="GenericOptions">Generic Options</h4> * * <p>The supported generic options are:</p> * <p><blockquote><pre> * -conf <configuration file> specify a configuration file * -D <property=value> use value for given property * -fs <local|namenode:port> specify a namenode * -jt <local|jobtracker:port> specify a job tracker * -files <comma separated list of files> specify comma separated * files to be copied to the map reduce cluster * -libjars <comma separated list of jars> specify comma separated * jar files to include in the classpath. * -archives <comma separated list of archives> specify comma * separated archives to be unarchived on the compute machines. * </pre></blockquote></p> * * <p>The general command line syntax is:</p> * <p><tt><pre> * bin/hadoop command [genericOptions] [commandOptions] * </pre></tt></p> * * <p>Generic command line arguments <strong>might</strong> modify * <code>Configuration </code> objects, given to constructors.</p> * * <p>The functionality is implemented using Commons CLI.</p> * * <p>Examples:</p> * <p><blockquote><pre> * $ bin/hadoop dfs -fs darwin:8020 -ls /data * list /data directory in dfs with namenode darwin:8020 * * $ bin/hadoop dfs -D fs.default.name=darwin:8020 -ls /data * list /data directory in dfs with namenode darwin:8020 * * $ bin/hadoop dfs -conf hadoop-site.xml -ls /data * list /data directory in dfs with conf specified in hadoop-site.xml * * $ bin/hadoop job -D mapred.job.tracker=darwin:50020 -submit job.xml * submit a job to job tracker darwin:50020 * * $ bin/hadoop job -jt darwin:50020 -submit job.xml * submit a job to job tracker darwin:50020 * * $ bin/hadoop job -jt local -submit job.xml * submit a job to local runner * * $ bin/hadoop jar -libjars testlib.jar * -archives test.tgz -files file.txt inputjar args * job submission with libjars, files and archives * </pre></blockquote></p> * * @see Tool * @see ToolRunner */ public class GenericOptionsParser { private static final Log LOG = LogFactory.getLog(GenericOptionsParser.class); private Configuration conf; private CommandLine commandLine; /** * Create an options parser with the given options to parse the args. * @param opts the options * @param args the command line arguments */ public GenericOptionsParser(Options opts, String[] args) { this(new Configuration(), new Options(), args); } /** * Create an options parser to parse the args. * @param args the command line arguments */ public GenericOptionsParser(String[] args) { this(new Configuration(), new Options(), args); } /** * Create a <code>GenericOptionsParser<code> to parse only the generic Hadoop * arguments. * * The array of string arguments other than the generic arguments can be * obtained by {@link #getRemainingArgs()}. * * @param conf the <code>Configuration</code> to modify. * @param args command-line arguments. */ public GenericOptionsParser(Configuration conf, String[] args) { this(conf, new Options(), args); } /** * Create a <code>GenericOptionsParser</code> to parse given options as well * as generic Hadoop options. * * The resulting <code>CommandLine</code> object can be obtained by * {@link #getCommandLine()}. * * @param conf the configuration to modify * @param options options built by the caller * @param args User-specified arguments */ public GenericOptionsParser(Configuration conf, Options options, String[] args) { parseGeneralOptions(options, conf, args); this.conf = conf; } /** * Returns an array of Strings containing only application-specific arguments. * * @return array of <code>String</code>s containing the un-parsed arguments * or <strong>empty array</strong> if commandLine was not defined. */ public String[] getRemainingArgs() { return (commandLine == null) ? new String[] {} : commandLine.getArgs(); } /** * Get the modified configuration * @return the configuration that has the modified parameters. */ public Configuration getConfiguration() { return conf; } /** * Returns the commons-cli <code>CommandLine</code> object * to process the parsed arguments. * * Note: If the object is created with * {@link #GenericOptionsParser(Configuration, String[])}, then returned * object will only contain parsed generic options. * * @return <code>CommandLine</code> representing list of arguments * parsed against Options descriptor. */ public CommandLine getCommandLine() { return commandLine; } /** * Specify properties of each generic option */ @SuppressWarnings("static-access") private static Options buildGeneralOptions(Options opts) { Option fs = OptionBuilder.withArgName("local|namenode:port").hasArg().withDescription("specify a namenode") .create("fs"); Option jt = OptionBuilder.withArgName("local|jobtracker:port").hasArg() .withDescription("specify a job tracker").create("jt"); Option oconf = OptionBuilder.withArgName("configuration file").hasArg() .withDescription("specify an application configuration file").create("conf"); Option property = OptionBuilder.withArgName("property=value").hasArg() .withDescription("use value for given property").create('D'); Option libjars = OptionBuilder.withArgName("paths").hasArg() .withDescription("comma separated jar files to include in the classpath.").create("libjars"); Option files = OptionBuilder.withArgName("paths").hasArg() .withDescription("comma separated files to be copied to the " + "map reduce cluster") .create("files"); Option archives = OptionBuilder.withArgName("paths").hasArg() .withDescription("comma separated archives to be unarchived" + " on the compute machines.") .create("archives"); opts.addOption(fs); opts.addOption(jt); opts.addOption(oconf); opts.addOption(property); opts.addOption(libjars); opts.addOption(files); opts.addOption(archives); return opts; } /** * Modify configuration according user-specified generic options * @param conf Configuration to be modified * @param line User-specified generic options */ private void processGeneralOptions(Configuration conf, CommandLine line) { if (line.hasOption("fs")) { FileSystem.setDefaultUri(conf, line.getOptionValue("fs")); } if (line.hasOption("jt")) { conf.set("mapred.job.tracker", line.getOptionValue("jt")); } if (line.hasOption("conf")) { String[] values = line.getOptionValues("conf"); for (String value : values) { conf.addResource(new Path(value)); } } try { if (line.hasOption("libjars")) { conf.set("tmpjars", validateFiles(line.getOptionValue("libjars"), conf)); //setting libjars in client classpath URL[] libjars = getLibJars(conf); if (libjars != null && libjars.length > 0) { conf.setClassLoader(new URLClassLoader(libjars, conf.getClassLoader())); Thread.currentThread().setContextClassLoader( new URLClassLoader(libjars, Thread.currentThread().getContextClassLoader())); } } if (line.hasOption("files")) { conf.set("tmpfiles", validateFiles(line.getOptionValue("files"), conf)); } if (line.hasOption("archives")) { conf.set("tmparchives", validateFiles(line.getOptionValue("archives"), conf)); } } catch (IOException ioe) { System.err.println(StringUtils.stringifyException(ioe)); } if (line.hasOption('D')) { String[] property = line.getOptionValues('D'); for (String prop : property) { String[] keyval = prop.split("=", 2); if (keyval.length == 2) { conf.set(keyval[0], keyval[1]); } } } conf.setBoolean("mapred.used.genericoptionsparser", true); } /** * If libjars are set in the conf, parse the libjars. * @param conf * @return libjar urls * @throws IOException */ public static URL[] getLibJars(Configuration conf) throws IOException { String jars = conf.get("tmpjars"); if (jars == null) { return null; } String[] files = jars.split(","); URL[] cp = new URL[files.length]; for (int i = 0; i < cp.length; i++) { Path tmp = new Path(files[i]); cp[i] = FileSystem.getLocal(conf).pathToFile(tmp).toURI().toURL(); } return cp; } /** * takes input as a comma separated list of files * and verifies if they exist. It defaults for file:/// * if the files specified do not have a scheme. * it returns the paths uri converted defaulting to file:///. * So an input of /home/user/file1,/home/user/file2 would return * file:///home/user/file1,file:///home/user/file2 * @param files * @return */ private String validateFiles(String files, Configuration conf) throws IOException { if (files == null) return null; String[] fileArr = files.split(","); String[] finalArr = new String[fileArr.length]; for (int i = 0; i < fileArr.length; i++) { String tmp = fileArr[i]; String finalPath; Path path = new Path(tmp); URI pathURI = path.toUri(); FileSystem localFs = FileSystem.getLocal(conf); if (pathURI.getScheme() == null) { //default to the local file system //check if the file exists or not first if (!localFs.exists(path)) { throw new FileNotFoundException("File " + tmp + " does not exist."); } finalPath = path.makeQualified(localFs).toString(); } else { // check if the file exists in this file system // we need to recreate this filesystem object to copy // these files to the file system jobtracker is running // on. FileSystem fs = path.getFileSystem(conf); if (!fs.exists(path)) { throw new FileNotFoundException("File " + tmp + " does not exist."); } finalPath = path.makeQualified(fs).toString(); try { fs.close(); } catch (IOException e) { } ; } finalArr[i] = finalPath; } return StringUtils.arrayToString(finalArr); } /** * Parse the user-specified options, get the generic options, and modify * configuration accordingly * @param conf Configuration to be modified * @param args User-specified arguments * @return Command-specific arguments */ private String[] parseGeneralOptions(Options opts, Configuration conf, String[] args) { opts = buildGeneralOptions(opts); CommandLineParser parser = new GnuParser(); try { commandLine = parser.parse(opts, args, true); processGeneralOptions(conf, commandLine); return commandLine.getArgs(); } catch (ParseException e) { LOG.warn("options parsing failed: " + e.getMessage()); HelpFormatter formatter = new HelpFormatter(); formatter.printHelp("general options are: ", opts); } return args; } /** * Print the usage message for generic command-line options supported. * * @param out stream to print the usage message to. */ public static void printGenericCommandUsage(PrintStream out) { out.println("Generic options supported are"); out.println("-conf <configuration file> specify an application configuration file"); out.println("-D <property=value> use value for given property"); out.println("-fs <local|namenode:port> specify a namenode"); out.println("-jt <local|jobtracker:port> specify a job tracker"); out.println("-files <comma separated list of files> " + "specify comma separated files to be copied to the map reduce cluster"); out.println("-libjars <comma separated list of jars> " + "specify comma separated jar files to include in the classpath."); out.println("-archives <comma separated list of archives> " + "specify comma separated archives to be unarchived" + " on the compute machines.\n"); out.println("The general command line syntax is"); out.println("bin/hadoop command [genericOptions] [commandOptions]\n"); } }