referer——防盗链

referer 实现防盗链

request_referer.java :

package cn.request;

import java.io.IOException;
import java.io.PrintWriter;

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

//referer防盗链
public class request_referer extends HttpServlet {

	
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		//设置浏览器以什么编码打开
		response.setCharacterEncoding("UTF-8");
		response.setContentType("text/html;UTF-8");
		String referer = request.getHeader("referer");//获取请求头
		//判断这个头是否为空，或这个头的首地址是否为http://localhost，如果不是则重定向
		if(referer==null || !referer.startsWith("http://localhost") )
		{
			response.sendRedirect("/Servlet_1/1.html");
			return;
		}
		String str="你好";
		response.getWriter().write(str);
	
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

	
	}

}

如果在浏览器地址栏直接链接： http://localhost:8080/Servlet_1/servlet/request_referer 则获取的请求头为空，因为不是从http://localhost 链接过来的，属于盗链行为，则重定向