Http协议（防止盗链）

public class ShowServlet extends HttpServlet {

@Override
protected void service(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {

resp.setContentType("text/html;charset=utf-8");

PrintWriter out = resp.getWriter();

//获取请求头中的Referer信息---来自哪里
String ref = req.getHeader("Referer");
String str ="";
if(ref==null){
str = "请先看广告!";
}else{
if(ref.contains("helloWeb")){
str = "<img src='imgs/1.jpg'/>"+
"<img src='imgs/2.jpg'/>"+
"<img src='imgs/3.jpg'/>"+
"<img src='imgs/4.jpg'/>湖南城市学院";
}else{
str="来自盗连页面!";
}
}
out.print(str);
}
}