Servlet如何输出所有头信息呢？
下文讲述使用Servlet输出头信息的方法分享，如下所示:
输出客户端所有头信息的方法分享
实现思路:
使用ServletRequest对象中的getHeaderNames()方法
即可返回一个包含所有头名称的Enumeration对象
getHeaderNames()方法的语法
getHeaderNames()方法的语法 public Enumeration getHeaderNames() getHeader()方法的语法 public String getHeader(String headerName)例:
输出客户端所有头信息的方法分享
index.html:调用Servlet对象
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>ShowHeaders Servlet</title>
</head>
<body>
<div style="text-align: center;">
请<a href="/servlet/HelloServlet?info=other">点击这里</a>查看所有报头信息
</div>
</body>
</html>
HelloServlet.java
package com.java265;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class HelloServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
Enumeration enums = request.getHeaderNames();
while (enums.hasMoreElements()) {
String headerName = (String) enums.nextElement();
String headerValue = request.getHeader(headerName);
out.print("<b>" + headerName + "</b>: ");
out.println(headerValue + "<br/>");
}
}
}
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
id="WebApp_ID" version="3.1">
<display-name>ShowHeaders-HeaderServlet</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<servlet>
<servlet-name>HelloServlet</servlet-name>
<servlet-class>com.java265.HelloServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>HelloServlet</servlet-name>
<url-pattern>/HelloServlet</url-pattern>
</servlet-mapping>
</web-app>
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