ServerInterceptor.java :  » RSS-RDF » sesame » org » openrdf » http » server » Java Open Source

/*
 * Copyright Aduna (http://www.aduna-software.com/) (c) 2007.
 *
 * Licensed under the Aduna BSD-style license.
 */
package org.openrdf.http.server;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;


/**
 * Base class for single-use request interceptors. This implementation sets the
 * thread name to something sensible at the start of the request handling and
 * resets the name at the end. This is useful for logging frameworks that make
 * use of thread names, such as Log4J. Should not be a singleton bean! Configure
 * as inner bean in openrdf-servlet.xml
 * 
 * @author Herko ter Horst
 */
public abstract class ServerInterceptor extends HandlerInterceptorAdapter {

  private String origThreadName;

  @Override
  public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
    throws Exception
  {
    origThreadName = Thread.currentThread().getName();
    Thread.currentThread().setName(getThreadName());

    setRequestAttributes(request);

    return super.preHandle(request, response, handler);
  }

  @Override
  public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler,
      Exception exception)
    throws Exception
  {
    cleanUpResources();
    Thread.currentThread().setName(origThreadName);
  }

  /**
   * Determine the thread name to use. Called before the request is forwarded
   * to a handler.
   * 
   * @param request
   *        the request
   * @return a name that makes sense based on the request
   * @throws ServerHTTPException
   *         if it was impossible to determine a name due to an internal error
   */
  protected abstract String getThreadName()
    throws ServerHTTPException;

  /**
   * Set attributes for this request. Called before the request is forwarded to
   * a handler. By default, this method does nothing.
   * 
   * @param request
   *        the request
   * @throws ClientHTTPException
   *         if it was impossible to set one or more attributes due to a bad
   *         request on the part of the client
   * @throws ServerHTTPException
   *         if it was impossible to set one or more attributes due to an
   *         internal error
   */
  protected void setRequestAttributes(HttpServletRequest request)
    throws ClientHTTPException, ServerHTTPException
  {
  }

  /**
   * Clean up resources used in handling this request. Called after the request
   * is handled and a the view is rendered (or an exception has occurred). By
   * default, this method does nothing.
   * 
   * @throws ServerHTTPException
   *         if some resources could not be cleaned up because of an internal
   *         error
   */
  protected void cleanUpResources()
    throws ServerHTTPException
  {
  }
}