servlet实现防盗链

防盗链是指通过判断HTTP请求的Referer头信息来限制或拒绝非法的站点访问资源。在Servlet中实现防盗链可以通过获取请求头中的Referer，并与允许的站点进行比较来判断是否为合法的访问。以下是一个简单的实现示例：

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class AntiLeechServlet extends HttpServlet {
  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    String referer = request.getHeader("referer");
    if (referer == null || !referer.startsWith("http://www.example.com")) {
      // 如果referer为空或者不是合法的访问来源，返回错误信息
      response.setContentType("text/html;charset=utf-8");
      response.getWriter().println("<h1>盗链可耻！！！</h1>");
    } else {
      // 合法的访问来源，返回正常内容
      response.setContentType("text/html;charset=utf-8");
      response.getWriter().println("<h1>欢迎访问^_^！！</h1>");
    }
  }

  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    doGet(request, response);
  }
}