# UnitOfWorkFilter.java

    /*
     * Copyright (c) 2008, Rickard Öberg. All Rights Reserved.
     *
     * 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.qi4j.library.http;

    import java.io.IOException;
    import javax.servlet.Filter;
    import javax.servlet.FilterChain;
    import javax.servlet.FilterConfig;
    import javax.servlet.ServletException;
    import javax.servlet.ServletRequest;
    import javax.servlet.ServletResponse;
    import org.qi4j.api.injection.scope.Structure;
    import org.qi4j.api.unitofwork.UnitOfWork;
    import org.qi4j.api.unitofwork.UnitOfWorkFactory;

    /**
     * JAVADOC
     */
    public class UnitOfWorkFilter
        implements Filter
    {
        @Structure private UnitOfWorkFactory uowf;

        @Override
        public void init( FilterConfig filterConfig )
            throws ServletException
        {
        }

        @Override
        public void doFilter( ServletRequest request, ServletResponse response, FilterChain chain )
            throws IOException, ServletException
        {
            UnitOfWork unitOfWork = uowf.newUnitOfWork();
            try
            {
                chain.doFilter( request, response );

                if( unitOfWork.isOpen() )
                {
                    unitOfWork.complete();
                }
            }
            catch( Exception e )
            {
                unitOfWork.discard();
            }

        }

        @Override
        public void destroy()
        {
        }
    }