com.mindmutex.draugiem.DraugiemHttpFilter.java Source code

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Here is the source code for com.mindmutex.draugiem.DraugiemHttpFilter.java

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/**
 * Copyright (C) 2011 by mindmutex.com
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package com.mindmutex.draugiem;

import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.mindmutex.draugiem.exceptions.DraugiemException;
import com.mindmutex.draugiem.filters.InnerFilter;
import com.mindmutex.draugiem.filters.InnerFilterChain;
import com.mindmutex.draugiem.filters.OncePerRequestFilter;

/**
 * Web application filter that would load draugiem.properties
 * configuration file and execute the internal filter chain which
 * would do something like authentication, authentication timeout
 * and session to context.
 *
 * The filters are defined in configuration file. If none is specified
 * the defaults are assumed {@link InnerFilterChain#createDefault(Properties)}.
 *
 * The default filter chain is chained even if the inner chain fails.
 *
 * Example:
 * <pre>
 *   <filter>
 *      <filter-name>DraugiemHttpFilter</filter-name>
 *      <filter-class>com.mindmutex.draugiem.DraugiemHttpFilter</filter-class>
 *      <init-param>
 *         <param-name>configPath</param-name>
 *         <param-value>META-INF/draugiem.properties</param-value>
 *   </init-param>
 *   </filter>
 *
 *   <filter-mapping>
 *      <filter-name>DraugiemHttpFilter</filter-name>
 *      <url-pattern>/*</url-pattern>
 *   </filter-mapping>
 * </pre>
 *
 * @author ivarsv
 */
public class DraugiemHttpFilter extends OncePerRequestFilter {
    private Logger logger = LoggerFactory.getLogger(getClass());

    /**
     * Default draugiem.properties configuration file path.
     */
    public static String DEFAULT_CONFIG_PATH = "draugiem.properties";

    /**
     * Configuration options provided through the properties file.
     */
    private Properties configuration = null;

    /**
     * Inner filter chain containing draugiem.lv
     * library specific filters.
     */
    private InnerFilterChain innerChain = null;

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        String configPath = filterConfig.getInitParameter("configPath");
        if (configPath == null) {
            configPath = DEFAULT_CONFIG_PATH;
        }

        ClassLoader classLoader = getClass().getClassLoader();
        InputStream inputStream = classLoader.getResourceAsStream(configPath);
        if (inputStream == null) {
            throw new ServletException("unable to load configuration file: " + configPath);
        }
        configuration = new Properties();
        try {
            configuration.load(inputStream);
        } catch (IOException ex) {
            throw new ServletException(ex);
        }
        configureFilter();

        logger.info("Initialised");
    }

    /**
     * Configure the filter before the internal
     * filter chain is executed.
     */
    private void configureFilter() {
        // creates inner filter chain
        String filters = configuration.getProperty("application.filters");
        if (filters == null || filters.equalsIgnoreCase("default")) {
            innerChain = InnerFilterChain.createDefault(configuration);
        } else {
            innerChain = new InnerFilterChain(configuration);
            String packageName = getClass().getPackage().getName();

            String[] classNames = filters.split(",");
            for (String className : classNames) {
                className = StringUtils.trim(className);
                if (className.startsWith(".")) {
                    className = packageName + className;
                }
                try {
                    Class<?> clazz = Class.forName(className);

                    Object filter = clazz.newInstance();
                    if (!(filter instanceof InnerFilter)) {
                        throw new DraugiemException("application.filters must implement inner filter interface");
                    }
                    logger.info("Adding Filter: {}", className);

                    innerChain.addInnerFilter((InnerFilter) filter);
                } catch (ClassNotFoundException ex) {
                    throw new DraugiemException(ex);
                } catch (InstantiationException ex) {
                    throw new DraugiemException(ex);
                } catch (IllegalAccessException ex) {
                    throw new DraugiemException(ex);
                }
            }
        }
    }

    @Override
    public void doInternalFilter(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
            throws IOException, ServletException {

        try {
            innerChain.reset();
            innerChain.doFilter(request, response);

            filterChain.doFilter(request, response);
        } catch (Exception ex) {
            throw new ServletException(ex);
        }
    }
}