responseheaderfilter.java

esri的ArcGIS Server超级学习模板程序（for java）

package com.esri.solutions.jitk.web.util;

import java.io.IOException;
import java.util.Enumeration;

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 javax.servlet.http.HttpServletResponse;

/**
 * Sets response headers on resources applied to this Filter.  The
 * response headers that are to set are configured via init-params
 * of this Filter in the Web Deployment Descriptor.  Example:
 * 
 * <init-param>
 * 	<param-name>Cache-Control</param-name>
 *  <param-value>max-age=3600</param-value>
 * </init-param>
 * 
 * This will set the Cache-Control header on the response to "max-age=3600".
 */
public class ResponseHeaderFilter implements Filter {

	/**
	 * Reference to the configuration for this Filter.
	 */
	private FilterConfig m_config;
	
	/*
	 * (non-Javadoc)
	 * @see javax.servlet.Filter#destroy()
	 */
	public void destroy() {
	}

	/*
	 * (non-Javadoc)
	 * @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain)
	 */
	@SuppressWarnings("unchecked")
	public void doFilter(ServletRequest req, ServletResponse res,
			FilterChain chain) throws IOException, ServletException {

		Enumeration headers = m_config.getInitParameterNames();

		if (res instanceof HttpServletResponse) {
			HttpServletResponse httpRes = (HttpServletResponse) res;
			while (headers.hasMoreElements()) {
				String header = (String)headers.nextElement();
				String value = m_config.getInitParameter(header);
				httpRes.addHeader(header, value);
			}
		}
		
		chain.doFilter(req, res);
	}

	/*
	 * (non-Javadoc)
	 * @see javax.servlet.Filter#init(javax.servlet.FilterConfig)
	 */
	public void init(FilterConfig config) throws ServletException {
		m_config = config;
	}

}