src/org/apache/osgi/bundle/shell/HelpCommandImpl.java

/*
 *   Copyright 2005 The Apache Software Foundation
 *
 *   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 org.apache.osgi.bundle.shell;

import java.io.PrintStream;

import org.apache.osgi.service.shell.Command;
import org.apache.osgi.service.shell.ShellService;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;

public class HelpCommandImpl implements Command
{
    private BundleContext m_context = null;

    public HelpCommandImpl(BundleContext context)
    {
        m_context = context;
    }

    public String getName()
    {
        return "help";
    }

    public String getUsage()
    {
        return "help";
    }

    public String getShortDescription()
    {
        return "display shell commands.";
    }

    public void execute(String s, PrintStream out, PrintStream err)
    {
        try {
            // Get a reference to the shell service.
            ServiceReference ref = m_context.getServiceReference(
                org.apache.osgi.service.shell.ShellService.class.getName());

            if (ref != null)
            {
                ShellService ss = (ShellService) m_context.getService(ref);
                String[] cmds = ss.getCommands();
                String[] usage = new String[cmds.length];
                String[] desc = new String[cmds.length];
                int maxUsage = 0;
                for (int i = 0; i < cmds.length; i++)
                {
                    usage[i] = ss.getCommandUsage(cmds[i]);
                    desc[i] = ss.getCommandDescription(cmds[i]);
                    // Just in case the command has gone away.
                    if ((usage[i] != null) && (desc[i] != null))
                    {
                        maxUsage = Math.max(maxUsage, usage[i].length());
                    }
                }
                StringBuffer sb = new StringBuffer();
                for (int i = 0; i < cmds.length; i++)
                {
                    // Just in case the command has gone away.
                    if ((usage[i] != null) && (desc[i] != null))
                    {
                        sb.delete(0, sb.length());
                        for (int j = 0; j < (maxUsage - usage[i].length()); j++)
                        {
                            sb.append(' ');
                        }
                        out.println(usage[i] + sb + " - " + desc[i]);
                    }
                }
            }
            else
            {
                err.println("No ShellService is unavailable.");
            }
        } catch (Exception ex) {
            err.println(ex.toString());
        }
    }
}