ActiveMQ example source code file (AbstractCommand.java)

This example ActiveMQ source code file (AbstractCommand.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - ActiveMQ tags/keywords

abstractcommand, command, command_option_delimeter, command_option_delimeter, commandcontext, d, d, exception, exception, list, string, string, unrecognized, util

The ActiveMQ AbstractCommand.java source code

/**
 * 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.activemq.console.command;

import java.util.List;

import org.apache.activemq.ActiveMQConnectionMetaData;
import org.apache.activemq.console.CommandContext;

public abstract class AbstractCommand implements Command {
    public static final String COMMAND_OPTION_DELIMETER = ",";

    private boolean isPrintHelp;
    private boolean isPrintVersion;

    protected CommandContext context;

    public void setCommandContext(CommandContext context) {
        this.context = context;
    }
    
    /**
     * Execute a generic command, which includes parsing the options for the
     * command and running the specific task.
     * 
     * @param tokens - command arguments
     * @throws Exception
     */
    public void execute(List<String> tokens) throws Exception {
        // Parse the options specified by "-"
        parseOptions(tokens);

        // Print the help file of the task
        if (isPrintHelp) {
            printHelp();

            // Print the AMQ version
        } else if (isPrintVersion) {
            context.printVersion(ActiveMQConnectionMetaData.PROVIDER_VERSION);

            // Run the specified task
        } else {
            runTask(tokens);
        }
    }

    /**
     * Parse any option parameters in the command arguments specified by a '-'
     * as the first character of the token.
     * 
     * @param tokens - command arguments
     * @throws Exception
     */
    protected void parseOptions(List<String> tokens) throws Exception {
        while (!tokens.isEmpty()) {
            String token = tokens.remove(0);
            if (token.startsWith("-")) {
                // Token is an option
                handleOption(token, tokens);
            } else {
                // Push back to list of tokens
                tokens.add(0, token);
                return;
            }
        }
    }

    /**
     * Handle the general options for each command, which includes -h, -?,
     * --help, -D, --version.
     * 
     * @param token - option token to handle
     * @param tokens - succeeding command arguments
     * @throws Exception
     */
    protected void handleOption(String token, List<String> tokens) throws Exception {
        isPrintHelp = false;
        isPrintVersion = false;
        // If token is a help option
        if (token.equals("-h") || token.equals("-?") || token.equals("--help")) {
            isPrintHelp = true;
            tokens.clear();

            // If token is a version option
        } else if (token.equals("--version")) {
            isPrintVersion = true;
            tokens.clear();
        } else if (token.startsWith("-D")) {
            // If token is a system property define option
            String key = token.substring(2);
            String value = "";
            int pos = key.indexOf("=");
            if (pos >= 0) {
                value = key.substring(pos + 1);
                key = key.substring(0, pos);
            }
            System.setProperty(key, value);
        } else {
            // Token is unrecognized
            context.printInfo("Unrecognized option: " + token);
            isPrintHelp = true;
        }
    }

    /**
     * Run the specific task.
     * 
     * @param tokens - command arguments
     * @throws Exception
     */
    protected abstract void runTask(List<String> tokens) throws Exception;

    /**
     * Print the help messages for the specific task
     */
    protected abstract void printHelp();
}