com.ngdata.hbaseindexer.cli.BaseCli.java Source code

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Here is the source code for com.ngdata.hbaseindexer.cli.BaseCli.java

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/*
 * Copyright 2013 NGDATA nv
 *
 * 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.
 */
package com.ngdata.hbaseindexer.cli;

import com.google.common.collect.Lists;
import joptsimple.OptionParser;
import joptsimple.OptionException;
import joptsimple.OptionSet;
import org.apache.commons.io.IOUtils;
import org.apache.log4j.LogManager;
import org.apache.log4j.PropertyConfigurator;

import java.io.IOException;
import java.io.InputStream;
import java.util.regex.Pattern;

/**
 * Provides a basic framework for the various CLI tools.
 *
 * <p>Implementations can implement or override the following methods:</p>
 *
 * <ul>
 *     <li>{@link #setupOptionParser()}</li>
 *     <li>{@link #getCmdName()}</li>
 *     <li>{@link #run(OptionSet)}</li>
 *     <li>{@link #cleanup()}</li>
 * </ul>
 *
 * <p>Implementations should call the {@link #run(String[])} method from their "public static void main".</p>
 */
public abstract class BaseCli {
    public void run(String[] args) throws Exception {
        OptionParser parser = setupOptionParser();

        OptionSet options = null;
        try {
            options = parser.parse(args);
        } catch (OptionException e) {
            System.out.println("Error parsing command line options:");
            System.out.println(e.getMessage());
            printHelp(parser);
            System.exit(1);
        }

        if (options.has("h")) {
            printHelp(parser);
            System.exit(1);
        }

        if (!options.has("default-log")) {
            LogManager.resetConfiguration();
            PropertyConfigurator.configure(BaseCli.class.getResource("cli-log4j.properties"));
        }

        try {
            run(options);
        } catch (CliException e) {
            System.err.println();
            System.err.println(e.getMessage());
            System.exit(e.getExitCode());
        } catch (Exception e) {
            System.err.println();
            e.printStackTrace(System.err);
            System.exit(1);
        } finally {
            try {
                cleanup();
            } catch (Throwable t) {
                System.err.println("Error during cleanup:");
                t.printStackTrace();
            }
        }
    }

    /**
     * Optionally override this to add CLI options. The canonical usage is to first call super,
     * and then add your own options to it.
     */
    protected OptionParser setupOptionParser() {
        OptionParser parser = new OptionParser();
        parser.acceptsAll(Lists.newArrayList("h", "help"), "shows help for this command");
        parser.acceptsAll(Lists.newArrayList("dl", "default-log"), "don't override log4j config");
        return parser;
    }

    /**
     * The name of this command, for use in informational messages.
     */
    protected abstract String getCmdName();

    /**
     * Any cleanup that should be done. Called from a finally block around the {@link #run(OptionSet)} method.
     */
    protected void cleanup() {
    }

    /**
     * This method is where the actual work should be done. The canonical usage is to first call
     * super.
     */
    protected abstract void run(OptionSet options) throws Exception;

    protected void printHelp(OptionParser parser) throws IOException {
        printHelpHeader();
        parser.printHelpOn(System.out);
        printHelpFooter();
    }

    protected void printHelpHeader() throws IOException {
        String className = getClass().getName();
        String helpHeaderPath = className.replaceAll(Pattern.quote("."), "/") + "_help_header.txt";
        InputStream is = getClass().getClassLoader().getResourceAsStream(helpHeaderPath);
        if (is != null) {
            IOUtils.copy(is, System.out);
            System.out.println();
            System.out.println();
        }
    }

    protected void printHelpFooter() throws IOException {
        String className = getClass().getName();
        String helpHeaderPath = className.replaceAll(Pattern.quote("."), "/") + "_help_footer.txt";
        InputStream is = getClass().getClassLoader().getResourceAsStream(helpHeaderPath);
        if (is != null) {
            System.out.println();
            IOUtils.copy(is, System.out);
            System.out.println();
        }
    }
}