/**
 * 获取headers方法的相关方法，类似代码出现在servletConfig 和servletContext中
 * 
 * note: request有一个getHeaders方法（特殊情况下会用到），参见Evernote
 */
package cn.itcast.chapter04.request;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
import javax.servlet.*;
import javax.servlet.http.*;
public class RequestHeadersServlet extends HttpServlet {
	public void doGet(HttpServletRequest request,
        HttpServletResponse response)throws ServletException, IOException {
			response.setContentType("text/html;charset=utf-8");
			PrintWriter out = response.getWriter();
	         // 获取请求消息中所有头字段
			Enumeration headerNames = request.getHeaderNames();
			// 使用循环遍历所有请求头，并通过getHeader()方法获取一个指定名称的头字段
			while (headerNames.hasMoreElements()) {
				String headerName = (String) headerNames.nextElement();
				out.print(headerName + " : "
	                       + request.getHeader(headerName)+ "<br>");
			}
		}
		public void doPost(HttpServletRequest request,
	        HttpServletResponse response)throws ServletException, IOException {
			doGet(request, response);
		}
	}