| /** |
| * 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.util; |
| |
| import java.lang.reflect.InvocationTargetException; |
| import java.lang.reflect.Method; |
| import java.util.Map; |
| import java.util.TreeMap; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| |
| /** A driver that is used to run programs added to it |
| */ |
| @InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce"}) |
| @InterfaceStability.Unstable |
| public class ProgramDriver { |
| |
| /** |
| * A description of a program based on its class and a |
| * human-readable description. |
| */ |
| Map<String, ProgramDescription> programs; |
| |
| public ProgramDriver(){ |
| programs = new TreeMap<String, ProgramDescription>(); |
| } |
| |
| static private class ProgramDescription { |
| |
| static final Class<?>[] paramTypes = new Class<?>[] {String[].class}; |
| |
| /** |
| * Create a description of an example program. |
| * @param mainClass the class with the main for the example program |
| * @param description a string to display to the user in help messages |
| * @throws SecurityException if we can't use reflection |
| * @throws NoSuchMethodException if the class doesn't have a main method |
| */ |
| public ProgramDescription(Class<?> mainClass, |
| String description) |
| throws SecurityException, NoSuchMethodException { |
| this.main = mainClass.getMethod("main", paramTypes); |
| this.description = description; |
| } |
| |
| /** |
| * Invoke the example application with the given arguments |
| * @param args the arguments for the application |
| * @throws Throwable The exception thrown by the invoked method |
| */ |
| public void invoke(String[] args) |
| throws Throwable { |
| try { |
| main.invoke(null, new Object[]{args}); |
| } catch (InvocationTargetException except) { |
| throw except.getCause(); |
| } |
| } |
| |
| public String getDescription() { |
| return description; |
| } |
| |
| private Method main; |
| private String description; |
| } |
| |
| private static void printUsage(Map<String, ProgramDescription> programs) { |
| System.out.println("Valid program names are:"); |
| for(Map.Entry<String, ProgramDescription> item : programs.entrySet()) { |
| System.out.println(" " + item.getKey() + ": " + |
| item.getValue().getDescription()); |
| } |
| } |
| |
| /** |
| * This is the method that adds the classed to the repository |
| * @param name The name of the string you want the class instance to be called with |
| * @param mainClass The class that you want to add to the repository |
| * @param description The description of the class |
| * @throws NoSuchMethodException |
| * @throws SecurityException |
| */ |
| public void addClass(String name, Class<?> mainClass, String description) |
| throws Throwable { |
| programs.put(name , new ProgramDescription(mainClass, description)); |
| } |
| |
| /** |
| * This is a driver for the example programs. |
| * It looks at the first command line argument and tries to find an |
| * example program with that name. |
| * If it is found, it calls the main method in that class with the rest |
| * of the command line arguments. |
| * @param args The argument from the user. args[0] is the command to run. |
| * @return -1 on error, 0 on success |
| * @throws NoSuchMethodException |
| * @throws SecurityException |
| * @throws IllegalAccessException |
| * @throws IllegalArgumentException |
| * @throws Throwable Anything thrown by the example program's main |
| */ |
| public int run(String[] args) |
| throws Throwable |
| { |
| // Make sure they gave us a program name. |
| if (args.length == 0) { |
| System.out.println("An example program must be given as the" + |
| " first argument."); |
| printUsage(programs); |
| return -1; |
| } |
| |
| // And that it is good. |
| ProgramDescription pgm = programs.get(args[0]); |
| if (pgm == null) { |
| System.out.println("Unknown program '" + args[0] + "' chosen."); |
| printUsage(programs); |
| return -1; |
| } |
| |
| // Remove the leading argument and call main |
| String[] new_args = new String[args.length - 1]; |
| for(int i=1; i < args.length; ++i) { |
| new_args[i-1] = args[i]; |
| } |
| pgm.invoke(new_args); |
| return 0; |
| } |
| |
| /** |
| * API compatible with Hadoop 1.x |
| */ |
| public void driver(String[] argv) throws Throwable { |
| if (run(argv) == -1) { |
| System.exit(-1); |
| } |
| } |
| |
| } |