| /** |
| * 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.tools; |
| |
| import java.io.PrintStream; |
| |
| import org.apache.hadoop.conf.Configured; |
| import org.apache.hadoop.util.Tool; |
| |
| /** |
| * This program is a CLI utility base class utilizing hadoop Tool class. |
| */ |
| public abstract class CommandShell extends Configured implements Tool { |
| |
| private PrintStream out = System.out; |
| private PrintStream err = System.err; |
| |
| /** The subcommand instance for this shell command, if any. */ |
| private SubCommand subcommand = null; |
| |
| /** |
| * Return usage string for the command including any summary of subcommands. |
| */ |
| public abstract String getCommandUsage(); |
| |
| public void setSubCommand(SubCommand cmd) { |
| subcommand = cmd; |
| } |
| |
| public void setOut(PrintStream p) { |
| out = p; |
| } |
| |
| public PrintStream getOut() { |
| return out; |
| } |
| |
| public void setErr(PrintStream p) { |
| err = p; |
| } |
| |
| public PrintStream getErr() { |
| return err; |
| } |
| |
| @Override |
| public int run(String[] args) throws Exception { |
| int exitCode = 0; |
| try { |
| exitCode = init(args); |
| if (exitCode != 0 || subcommand == null) { |
| printShellUsage(); |
| return exitCode; |
| } |
| if (subcommand.validate()) { |
| subcommand.execute(); |
| } else { |
| printShellUsage(); |
| exitCode = 1; |
| } |
| } catch (Exception e) { |
| printShellUsage(); |
| printException(e); |
| return 1; |
| } |
| return exitCode; |
| } |
| |
| /** |
| * Parse the command line arguments and initialize subcommand instance. |
| * @param args |
| * @return 0 if the argument(s) were recognized, 1 otherwise |
| */ |
| protected abstract int init(String[] args) throws Exception; |
| |
| protected final void printShellUsage() { |
| if (subcommand != null) { |
| out.println(subcommand.getUsage()); |
| } else { |
| out.println(getCommandUsage()); |
| } |
| out.flush(); |
| } |
| |
| protected void printException(Exception ex){ |
| ex.printStackTrace(err); |
| } |
| |
| /** |
| * Base class for any subcommands of this shell command. |
| */ |
| protected abstract class SubCommand { |
| |
| public boolean validate() { |
| return true; |
| } |
| |
| public abstract void execute() throws Exception; |
| |
| public abstract String getUsage(); |
| } |
| } |