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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.marmotta.platform.core.servlet;
 
 
 import java.net.URL;
 import java.util.List;

This filter is used by KiWi for initialisation of the KiWi system on startup of the server. It does not perform any actual filtering. For this purpose, a listener would have been better, but CDI in Jetty does not support injection into listeners, so we "abuse" a filter for this purpose. Filters always get initialised before servlets, so by adding the KiWiFilter as the first entry into web.xml, we can ensure that the KiWi initialisation is done before everything else.

User: sschaffe

 
 public class MarmottaResourceFilter implements Filter {
 
     @Inject
     private Logger log;
 
     @Inject
 
     @Inject
     private ModuleService moduleService;
 
     @Inject @Any
     private Instance<MarmottaHttpFilterfilters;
 
     private List<MarmottaHttpFilterfilterList;

    
Called by the web container to indicate to a filter that it is being placed into service. The servlet container calls the init method exactly once after instantiating the filter. The init method must complete successfully before the filter is asked to do any filtering work.

The web container cannot place the filter into service if the init method either
1.Throws a ServletException
2.Does not return within a time period defined by the web container

 
     @Override
     public void init(FilterConfig filterConfigthrows ServletException {
         .info("Apache Marmotta Resource Filter {} starting up ... ".getConfiguration("kiwi.version"));
 
 
         // initialise filter chain and sort it according to priority
         this.  = new ArrayList<MarmottaHttpFilter>();
 
         for(MarmottaHttpFilter filter : ) {
             try {
                 filter.init(filterConfig);
                 .add(filter);
 
                 .debug("module {}: registered filter {}".getModuleConfiguration(filter.getClass()).getModuleName(), filter.getClass().getCanonicalName());
             } catch (ServletException ex) {
                 .error("could not instantiate filter {}, servlet exception during initialisation ({})",filter.getClass(),ex.getMessage());
             }
         }
 
         Collections.sort(,new FilterComparator());
 
    }



    
The doFilter method of the Filter is called by the container each time a request/response pair is passed through the chain due to a client request for a resource at the end of the chain. The FilterChain passed in to this method allows the Filter to pass on the request and response to the next entity in the chain.

A typical implementation of this method would follow the following pattern:-
1. Examine the request
2. Optionally wrap the request object with a custom implementation to filter content or headers for input filtering
3. Optionally wrap the response object with a custom implementation to filter content or headers for output filtering
4. a) Either invoke the next entity in the chain using the FilterChain object (chain.doFilter()),
* 4. b) or not pass on the request/response pair to the next entity in the filter chain to block the request processing
* 5. Directly set headers on the response after invocation of the next entity in the filter chain.

    @Override
    public void doFilter(ServletRequest requestServletResponse responseFilterChain chainthrows IOExceptionServletException {
        URL url = null;
        String prefix = nullpath = null;
        if (request instanceof HttpServletRequest) {
            url    = new URL(((HttpServletRequest)request).getRequestURL().toString());
            prefix = ((HttpServletRequest)request).getContextPath();
            if(url.getPath().startsWith(prefix)) {
                path = url.getPath().substring(prefix.length());
            }
        }
        new LMFFilterChain(path,chain).doFilter(request,response);
    }




    
Called by the web container to indicate to a filter that it is being taken out of service. This method is only called once all threads within the filter's doFilter method have exited or after a timeout period has passed. After the web container calls this method, it will not call the doFilter method again on this instance of the filter.

This method gives the filter an opportunity to clean up any resources that are being held (for example, memory, file handles, threads) and make sure that any persistent state is synchronized with the filter's current state in memory.

    @Override
    public void destroy() {
        for(MarmottaHttpFilter filter : ) {
            filter.destroy();
        }
    }


    
A special filter chain that implements the LMFHttpFilter calls
    private class LMFFilterChain implements FilterChain {
        private Iterator<MarmottaHttpFilterfilters;
        private String path;
        private FilterChain originalChain;
        LMFFilterChain(String pathFilterChain originalChain) {
            this.     = path;
            this. = .iterator();
            this. = originalChain;
        }
        @Override
        public void doFilter(ServletRequest requestServletResponse responsethrows IOExceptionServletException {
            if(.hasNext()) {
                MarmottaHttpFilter filter = .next();
                if(.matches(filter.getPattern())) {
                    filter.doFilter(request,response,this);
                } else {
                    doFilter(request,response);
                }
            } else {
                .doFilter(request,response);
            }
        }
    }
    private static class FilterComparator implements Comparator<MarmottaHttpFilter>, Serializable {
        private static final long serialVersionUID = -7264645592168345092L;

        
Compares its two arguments for order. Returns a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.

Parameters:
o1 the first object to be compared.
o2 the second object to be compared.
Returns:
a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.
Throws:
java.lang.ClassCastException if the arguments' types prevent them from being compared by this comparator.
        @Override
        public int compare(MarmottaHttpFilter o1MarmottaHttpFilter o2) {
            if(o1.getPriority() < o2.getPriority())
                return -1;
            else if(o1.getPriority() > o2.getPriority()) return 1;
            else
                return 0;
        }
    }
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