org.impalaframework.web.servlet.invocation.InvocationChain.java Source code

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Here is the source code for org.impalaframework.web.servlet.invocation.InvocationChain.java

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/*
 * Copyright 2007-2010 the original author or authors.
 * 
 * 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.impalaframework.web.servlet.invocation;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.Servlet;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.impalaframework.web.servlet.invoker.HttpServiceInvoker;
import org.springframework.util.ObjectUtils;

/**
 * Implements Filter and Servlet invocation chain. 
 * Filters invoked in order (as long as each filter calls {@link FilterChain#doFilter(ServletRequest, ServletResponse)}.
 * Finally, {@link Servlet#service(ServletRequest, ServletResponse)} is invoked.
 * 
 * This allows for the same filter/servlet invocation orders as occurs in a web container.
 * The main difference, however, is that only filters/servlets defined within the module are invoked.
 * 
 * @author Phil Zoio
 */
public class InvocationChain implements HttpServiceInvoker, FilterChain {

    private static final Log logger = LogFactory.getLog(InvocationChain.class);

    private final List<Filter> filters = new ArrayList<Filter>();
    private final Servlet servlet;
    private int filterCount;

    private boolean incomplete;

    /**
     * Invocation chain consisting of zero or more filters, plus optional servlet
     * @param filters
     * @param servlet
     */
    public InvocationChain(List<Filter> filters, Servlet servlet) {
        super();
        if (filters != null) {
            this.filters.addAll(filters);
        }
        this.servlet = servlet;
    }

    public void invoke(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
            throws ServletException, IOException {

        if (filterCount < filters.size()) {
            int currentCount = filterCount;
            filterCount++;

            Filter filter = filters.get(currentCount);

            if (logger.isDebugEnabled())
                logger.debug("Getting filter for " + currentCount + ObjectUtils.identityToString(filter));

            filter.doFilter(request, response, this);
        } else if (servlet != null) {
            servlet.service(request, response);
        } else {
            incomplete = true;
        }
    }

    public void doFilter(ServletRequest request, ServletResponse response) throws IOException, ServletException {

        invoke((HttpServletRequest) request, (HttpServletResponse) response, this);

    }

    public boolean isComplete() {
        return !incomplete;
    }

    @Override
    public String toString() {
        StringBuffer buffer = new StringBuffer(500);
        buffer.append(this.getClass().getName()).append(": ");
        buffer.append("filters = ");
        if (this.filters != null)
            buffer.append(this.filters.toString());
        else
            buffer.append("value is null");
        buffer.append(", ");
        buffer.append("servlet = ");
        if (this.servlet != null)
            buffer.append(this.servlet.toString());
        else
            buffer.append("value is null");
        buffer.append("\n");
        return buffer.toString();
    }

}