Jetty example source code file (Holder.java)

This example Jetty source code file (Holder.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 - Jetty tags/keywords

abstractlifecycle, class, exception, exception, holder, holder, illegalaccessexception, instantiationexception, io, map, map, no, servlet, servlethandler, string, string, util

The Jetty Holder.java source code

// ========================================================================
// Copyright 1996-2005 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// 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.mortbay.jetty.servlet;

import java.io.Serializable;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;

import javax.servlet.UnavailableException;

import org.mortbay.component.AbstractLifeCycle;
import org.mortbay.log.Log;
import org.mortbay.util.Loader;


/* --------------------------------------------------------------------- */
/** 
 * @author Greg Wilkins
 */
public class Holder extends AbstractLifeCycle implements Serializable
{
    protected transient Class _class;
    protected String _className;
    protected String _displayName;
    protected Map _initParams;
    protected boolean _extInstance;

    /* ---------------------------------------------------------------- */
    protected String _name;
    protected ServletHandler _servletHandler;

    protected Holder()
    {}

    /* ---------------------------------------------------------------- */
    protected Holder(Class held)
    {
        _class=held;
        if (held!=null)
        {
            _className=held.getName();
            _name=held.getName()+"-"+this.hashCode();
        }
    }

    /* ------------------------------------------------------------ */
    public void doStart()
        throws Exception
    {
        //if no class already loaded and no classname, make servlet permanently unavailable
        if (_class==null && (_className==null || _className.equals("")))
            throw new UnavailableException("No class for Servlet or Filter", -1);
        
        //try to load class
        if (_class==null)
        {
            try
            {
                _class=Loader.loadClass(Holder.class, _className);
                if(Log.isDebugEnabled())Log.debug("Holding {}",_class);
            }
            catch (Exception e)
            {
                Log.warn(e);
                throw new UnavailableException(e.getMessage(), -1);
            }
        }
    }
    
    /* ------------------------------------------------------------ */
    public void doStop()
    {
        if (!_extInstance)
            _class=null;
    }
    
    /* ------------------------------------------------------------ */
    public String getClassName()
    {
        return _className;
    }
    
    /* ------------------------------------------------------------ */
    public Class getHeldClass()
    {
        return _class;
    }
    
    /* ------------------------------------------------------------ */
    public String getDisplayName()
    {
        return _displayName;
    }

    /* ---------------------------------------------------------------- */
    public String getInitParameter(String param)
    {
        if (_initParams==null)
            return null;
        return (String)_initParams.get(param);
    }
    
    /* ------------------------------------------------------------ */
    public Enumeration getInitParameterNames()
    {
        if (_initParams==null)
            return Collections.enumeration(Collections.EMPTY_LIST);
        return Collections.enumeration(_initParams.keySet());
    }

    /* ---------------------------------------------------------------- */
    public Map getInitParameters()
    {
        return _initParams;
    }
    
    /* ------------------------------------------------------------ */
    public String getName()
    {
        return _name;
    }
    
    /* ------------------------------------------------------------ */
    /**
     * @return Returns the servletHandler.
     */
    public ServletHandler getServletHandler()
    {
        return _servletHandler;
    }
    
    /* ------------------------------------------------------------ */
    public synchronized Object newInstance()
        throws InstantiationException,
               IllegalAccessException
    {
        if (_class==null)
            throw new InstantiationException("!"+_className);
        return _class.newInstance();
    }
    
    public void destroyInstance(Object instance)
    throws Exception
    {
    }
    
    /* ------------------------------------------------------------ */
    /**
     * @param className The className to set.
     */
    public void setClassName(String className)
    {
        _className = className;
        _class=null;
    }
    
    /* ------------------------------------------------------------ */
    /**
     * @param className The className to set.
     */
    public void setHeldClass(Class held)
    {
        _class=held;
        _className = held!=null?held.getName():null;
    }
    
    /* ------------------------------------------------------------ */
    public void setDisplayName(String name)
    {
        _displayName=name;
    }
    
    /* ------------------------------------------------------------ */
    public void setInitParameter(String param,String value)
    {
        if (_initParams==null)
            _initParams=new HashMap(3);
        _initParams.put(param,value);
    }
    
    /* ---------------------------------------------------------------- */
    public void setInitParameters(Map map)
    {
        _initParams=map;
    }
    
    /* ------------------------------------------------------------ */
    /**
     * The name is a primary key for the held object.
     * Ensure that the name is set BEFORE adding a Holder
     * (eg ServletHolder or FilterHolder) to a ServletHandler.
     * @param name The name to set.
     */
    public void setName(String name)
    {
        _name = name;
    }
    
    /* ------------------------------------------------------------ */
    /**
     * @param servletHandler The {@link ServletHandler} that will handle requests dispatched to this servlet.
     */
    public void setServletHandler(ServletHandler servletHandler)
    {
        _servletHandler = servletHandler;
    }
    
    /* ------------------------------------------------------------ */
    public String toString()
    {
        return _name;
    }
}