httpwrapper.java

OSGI这是一个中间件,与UPNP齐名,是用于移植到嵌入式平台之上

/*
 * Copyright (c) 2003, KNOPFLERFISH project
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following
 * conditions are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials
 *   provided with the distribution.
 *
 * - Neither the name of the KNOPFLERFISH project nor the names of its
 *   contributors may be used to endorse or promote products derived
 *   from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.knopflerfish.bundle.httpconsole;

import java.util.Hashtable;
import javax.servlet.http.HttpServlet;

import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceListener;
import org.osgi.framework.ServiceReference;
import org.osgi.framework.InvalidSyntaxException;
import org.osgi.framework.ServiceEvent;
import org.osgi.util.tracker.ServiceTracker;
import org.osgi.service.http.HttpService;
import org.osgi.service.http.HttpContext;

/**
 * <p>
 * Wrapper class which listens for all framework services of
 * class HttpServlet or HttpContext. Each such service is picked
 * up and installed into actual running HttpServices
 * </p>
 * <p>
 * <p>
 * The alias used for the servlet/resource is taken from the 
 * PROP_ALIAS service property.
 * </p>
 * <p>
 * The resource dir used for contexts is taken from the 
 * PROP_DIR service property.
 * </p>
 */
public class HttpWrapper {

  /**
   * Service property name for HttpServlet and HttpContexts alias
   *
   * <p>
   * Value is <tt>httpwrapper.resource.alias</tt>
   * </p>
   */
  public static String PROP_ALIAS = "httpwrapper.resource.alias";

  /**
   * Service property name for HttpContext resource dir
   *
   * <p>
   * Value is <tt>httpwrapper.resource.dir</tt>
   * </p>
   */
  public static String PROP_DIR   = "httpwrapper.resource.dir";

  BundleContext  bc;
  ServiceTracker httpTracker;

  HttpWrapper(BundleContext bc) {
    this.bc = bc;
  }
  
  void open() {
    try {
      String httpFilter = 
	System.getProperty("org.knopflerfish.httpconsole.filter",
			   "(objectclass=org.osgi.service.http.HttpService)");
      httpTracker = new ServiceTracker(bc, bc.createFilter(httpFilter), null);
      httpTracker.open();
    } catch (InvalidSyntaxException e) {
      throw new RuntimeException("Failed to set up http tracker: " + e);
    }

    ServiceListener sl = new ServiceListener() {
	public void serviceChanged(ServiceEvent ev) {
	  ServiceReference sr = ev.getServiceReference();
	  switch(ev.getType()) {
	  case ServiceEvent.REGISTERED:
	    {
              register(sr);
	    }
	    break;
	  case ServiceEvent.UNREGISTERING:
	    {
              unregister(sr);
	    }
	    break;
	  }
	}
      };
    
    String filter = 
      "(|" + 
      "(objectclass=" + HttpServlet.class.getName() + ")" + 
      "(objectclass=" + HttpContext.class.getName() + ")" + 
      ")";

    try {
      bc.addServiceListener(sl, filter);
      ServiceReference[] srl = bc.getServiceReferences(null, filter);
      for(int i = 0; srl != null && i < srl.length; i++) {
	sl.serviceChanged(new ServiceEvent(ServiceEvent.REGISTERED,
					   srl[i]));
      }
    } catch (InvalidSyntaxException e) { 
      e.printStackTrace(); 
    }
  }
  
  void register(ServiceReference sr) {
    // resource is either a HttpServlet or a HttpContext
    // Use instanceof to check the type
    Object resource = bc.getService(sr); 

    // all resources must have an alias
    String alias    = (String)sr.getProperty(PROP_ALIAS);

    if(resource == null) {
      Activator.log.warn("http resource is null");
      return;
    }
    if(alias == null || "".equals(alias)) {
      Activator.log.warn(PROP_ALIAS + " must be set, is " + alias);
      return;
    }

    Object[] httplist = httpTracker.getServices();
    
    for(int i = 0; httplist != null && i < httplist.length; i++) {
      HttpService http = (HttpService)httplist[i];
      try {
	if(resource instanceof HttpServlet) {
	  Hashtable props = new Hashtable();
	  http.registerServlet(alias, (HttpServlet)resource, props, null);
	} else if(resource instanceof HttpContext) {
	  String dir        = (String)sr.getProperty(PROP_DIR);
	  http.registerResources(alias, dir, (HttpContext)resource);
	}
      } catch (Exception e) {
	Activator.log.error("Failed to register resource, alias=" + alias, e);
      }
    }
  }
  
  void unregister(ServiceReference sr) {
    String alias        = (String)sr.getProperty(PROP_ALIAS);
    
    Object[] httplist = httpTracker.getServices();
    
    for(int i = 0; httplist != null && i < httplist.length; i++) {
      HttpService http = (HttpService)httplist[i];
      try {
	http.unregister(alias);
      } catch (Exception e) {
	Activator.log.error("Failed to unregister resource, alias=" + alias, e);
      }
      bc.ungetService(sr);
    }
  }
}