servlet实现防盗链及文件下载

package servlet;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.net.URLEncoder;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/Test1")
public class Test1 extends HttpServlet {
private static final long serialVersionUID = 1L;

protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String refer = request.getHeader("referer");
String site = "http://" + request.getServerName();
if (refer != null && refer.startsWith(site)) {
String Directory = request.  
               getServletContext().getRealPath("/WEB-INF/");  
File file=new File(Directory+"\\file","测试.docx");
String filename=URLEncoder.encode(file.getName(),"utf-8");
response.setContentType("application/octet-stream");
response.setHeader("Content-Disposition","attachment;filename="+filename);
response.setHeader("Content-Length", file.length()+"");
BufferedInputStream bis=new BufferedInputStream(new FileInputStream(file));
BufferedOutputStream bos=new BufferedOutputStream(response.getOutputStream());
byte[] buffer = new byte[1024];
int i = -1;
while ((i = bis.read(buffer)) != -1) {
       bos.write(buffer, 0, i);
}
       bos.flush();
       bos.close();
       bis.close();       
}
else {
request.getRequestDispatcher("/download.html").forward(request, response);
}

}

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

}

download.html：

download here