classloaderfilterchain.java

来自「RESIN 3.2 最新源码」· Java 代码 · 共 82 行

/*
 * Copyright (c) 1998-2008 Caucho Technology -- all rights reserved
 *
 * This file is part of Resin(R) Open Source
 *
 * Each copy or derived work must preserve the copyright notice and this
 * notice unmodified.
 *
 * Resin Open Source is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Resin Open Source is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
 * of NON-INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Resin Open Source; if not, write to the
 *   Free SoftwareFoundation, Inc.
 *   59 Temple Place, Suite 330
 *   Boston, MA 02111-1307  USA
 *
 * @author Scott Ferguson
 */

package com.caucho.server.dispatch;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import java.io.IOException;

/**
 * Represents the next filter in a filter chain.  The final filter will
 * be the servlet itself.
 */
public class ClassLoaderFilterChain implements FilterChain {
  // Loader to use.
  private final ClassLoader _loader;
  private final FilterChain _next;

  /**
   * Creates a new FilterChainFilter.
   *
   * @param next the next filterChain
   * @param filter the user's filter
   */
  public ClassLoaderFilterChain(FilterChain next, ClassLoader loader)
  {
    _next = next;
    _loader = loader;
  }
  
  /**
   * Invokes the next filter in the chain or the final servlet at
   * the end of the chain.
   *
   * @param request the servlet request
   * @param response the servlet response
   * @since Servlet 2.3
   */
  public void doFilter(ServletRequest request,
                       ServletResponse response)
    throws ServletException, IOException
  {
    Thread thread = Thread.currentThread();
    ClassLoader oldLoader = thread.getContextClassLoader();

    try {
      thread.setContextClassLoader(_loader);

      _next.doFilter(request, response);
    } finally {
      thread.setContextClassLoader(oldLoader);
    }
  }
}