ape.ApeCommand.java Source code

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Here is the source code for ape.ApeCommand.java

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/**
  * Copyright (c) 2012 Yahoo! Inc. All rights reserved.
  * Licensed 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. See accompanying LICENSE file.
*/

package ape;

import java.io.IOException;
import java.util.Iterator;
import java.util.ServiceLoader;

import org.apache.commons.cli.Option;
import org.apache.commons.cli.ParseException;

/**
 * This is the abstract class that every Ape command must extend.
 * 
 *
 */
public abstract class ApeCommand {
    private static ServiceLoader<ApeCommand> loader = ServiceLoader.load(ApeCommand.class);

    public abstract String getName();

    protected abstract boolean runImpl(String[] args) throws ParseException, IOException;

    public abstract Option getOption();

    public boolean exec(String[] args) throws ParseException, IOException {
        return runImpl(args);
    }

    /**
     * This method uses the iterator inside the ServiceLoader class 
     * to get all the options that represents each implementation of ApeCommand
     */
    public static ApeCommand getCommand(String cmdname) {
        String name = cmdname.toLowerCase();

        Iterator<ApeCommand> iter = loader.iterator();
        while (iter.hasNext()) {
            ApeCommand ac = iter.next();
            if (name.equals(ac.getName().toLowerCase())) {
                return ac;
            }
        }
        return null;
    }
}