When the browser requests a web page, it sends a series of information to the network server that cannot be read directly because the information is transmitted as part of the HTTP header. You can check out the HTTP protocol for more information.
JSP client request syntax
After obtaining the Enumeration object, use the standard method to traverse the Enumeration object, use the hasMoreElements() method to determine when to stop, and use the nextElement() method to obtain the name of each parameter.
JSP client request example
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ page import="java.io.*,java.util.*" %>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php.cn</title>
</head>
<body>
<h2>HTTP 头部请求实例</h2>
<table width="100%" border="1" align="center">
<tr bgcolor="#949494">
<th>Header Name</th>
<th>Header Value(s)</th>
</tr>
<%Enumeration headerNames = request.getHeaderNames();
while(headerNames.hasMoreElements()) {
String paramName = (String)headerNames.nextElement();
out.print("<tr><td>" + paramName + "</td>\n");
String paramValue = request.getHeader(paramName);
out.println("<td> " + paramValue + "</td></tr>\n");}%>
</table>
</body>
</html>