让OSGi支持JSF Web开发

让OSGi支持JSF Web开发

1. 按照以下代码改写你自己的Activator (或者将代码中的"/pages"改成你的jsf网页路径)：
注意加粗的那段代码(使用当前的class loader来加载jsf的FacesServlet)

package  net.andyluo.singlife.jsf.demo;

import  java.io.IOException;
import  java.util.Dictionary;
import  java.util.Hashtable;

import  javax.faces.webapp.FacesServlet;
import  javax.servlet.Servlet;
import  javax.servlet.ServletConfig;
import  javax.servlet.ServletContextEvent;
import  javax.servlet.ServletContextListener;
import  javax.servlet.ServletException;
import  javax.servlet.ServletRequest;
import  javax.servlet.ServletResponse;

import  org.eclipse.equinox.http.helper.BundleEntryHttpContext;
import  org.eclipse.equinox.http.helper.ContextPathServletAdaptor;
import  org.eclipse.equinox.jsp.jasper.JspServlet;
import  org.osgi.framework.BundleActivator;
import  org.osgi.framework.BundleContext;
import  org.osgi.framework.ServiceReference;
import  org.osgi.service.http.HttpContext;
import  org.osgi.service.http.HttpService;
import  org.osgi.util.tracker.ServiceTracker;

import  com.sun.faces.config.ConfigureListener;

public   class  Activator  implements  BundleActivator 
{

     private  ServiceTracker httpServiceTracker;

     public   void  start(BundleContext context)  throws  Exception 
     {
        httpServiceTracker  =   new  HttpServiceTracker(context);
        httpServiceTracker.open();
    }

     public   void  stop(BundleContext context)  throws  Exception 
     {
        httpServiceTracker.close();
    }

     private   class  HttpServiceTracker  extends  ServiceTracker 
     {

         private   static   final  String PATH  =   " /jsf " ;

         public  HttpServiceTracker(BundleContext context) 
         {
             super (context, HttpService. class .getName(),  null );
        }

         public  Object addingService(ServiceReference reference) 
         {
             final  HttpService httpService  =  (HttpService) context
                    .getService(reference);
             try  
             {
                HttpContext commonContext  =   new  BundleEntryHttpContext(context
                        .getBundle(),  " /pages " );
                httpService.registerResources(PATH,  " / " , commonContext);

                JspServlet jspServlet  =   new  JspServlet(context.getBundle(),
                         " /pages " );
                Servlet adaptedJspServlet  =   new  ContextPathServletAdaptor(
                        jspServlet, PATH);
                httpService.registerServlet(PATH  +   " /*.jsp " , adaptedJspServlet,
                         null , commonContext);

                Dictionary initparams  =   new  Hashtable();
                initparams.put( " servlet-name " ,  " Faces Servlet " );
                Servlet adaptedFacesServlet  =   new  ServletContextListenerServletAdaptor(
                         new  ConfigureListener(),  new  FacesServlet(), jspServlet
                                .getJspLoader());
                adaptedFacesServlet  =   new  ContextPathServletAdaptor(
                        adaptedFacesServlet, PATH);
                httpService.registerServlet(PATH  +   " /*.jsf " ,
                        adaptedFacesServlet, initparams, commonContext);

            }   catch  (Exception e) 
             {
                e.printStackTrace();
            }
             return  httpService;
        }

         public   void  removedService(ServiceReference reference, Object service) 
         {
             final  HttpService httpService  =  (HttpService) service;
            httpService.unregister(PATH);  // $NON-NLS-1$
            httpService.unregister(PATH  +   " /*.jsp " );  // $NON-NLS-1$
            httpService.unregister(PATH  +   " /*.jsf " );  // $NON-NLS-1$            
             super .removedService(reference, service);
        }
    }

     public   class  ServletContextListenerServletAdaptor  implements  Servlet 
     {
         private  ServletConfig config;

         private  ServletContextListener listener;

         private  Servlet delegate;

         private  ClassLoader jspLoader;

         public  ServletContextListenerServletAdaptor(
                ServletContextListener listener, Servlet delegate,
                ClassLoader jspLoader) 
         {
             this .listener  =  listener;
             this .delegate  =  delegate;
             this .jspLoader  =  jspLoader;
        }

         public   void  init(ServletConfig config)  throws  ServletException 
         {
             this .config  =  config;
            ClassLoader original  =  Thread.currentThread()
                    .getContextClassLoader();
             try  
             {
                Thread.currentThread().setContextClassLoader(jspLoader);
                listener.contextInitialized( new  ServletContextEvent(config
                        .getServletContext()));
                delegate.init(config);
            }   finally  
             {
                Thread.currentThread().setContextClassLoader(original);
            }
        }

         public   void  service(ServletRequest req, ServletResponse resp)
                 throws  ServletException, IOException 
         {
            ClassLoader original  =  Thread.currentThread()
                    .getContextClassLoader();
             try  
             {
                Thread.currentThread().setContextClassLoader(jspLoader);
                delegate.service(req, resp);
            }   finally  
             {
                Thread.currentThread().setContextClassLoader(original);
            }
        }

         public   void  destroy() 
         {
            ClassLoader original  =  Thread.currentThread()
                    .getContextClassLoader();
             try  
             {
                Thread.currentThread().setContextClassLoader(jspLoader);
                delegate.destroy();
                listener.contextDestroyed( new  ServletContextEvent(config
                        .getServletContext()));
                config  =   null ;
            }   finally  
             {
                Thread.currentThread().setContextClassLoader(original);
            }
        }

         public  ServletConfig getServletConfig() 
         {
             return  config;
        }

         public  String getServletInfo() 
         {
             return   "" ;
        }
    }

}

2. 因为JspServlet中没有返回class loader的方法，所以我们要更改一下JspServlet的实现代码（hack一下）：更改equinox的 org.eclipse.equinox.jsp.jasper_*.jar中的 org.eclipse.equinox.jsp.jasper.JspServlet类：（可以下载JspServlet的源代码，在本地更改编译成功 后将class文件覆盖到org.eclipse.equinox.jsp.jasper_*.jar中）

添加以下方法：
    public ClassLoader getJspLoader()
    {
        return this.jspLoader;
    }

如此即可^_^, 其实就是让FacesServlet使用JspServlet的ClassLoader，这样就不会出现"Can't find FacesContext"错误了。