可以两重防护：JS和一个"令牌"：
<form οnsubmit="return check()"
js代码:
<script type="text/javascript"> var is=false; function check(){ if(!is){ is=true; return true; } else return false; } </script>
可以两重防护：JS和一个"令牌"；public class formServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setCharacterEncoding("UTF-8"); response.setContentType("text/html"); PrintWriter out = response.getWriter(); //产生随机数（表单号） TokenProcessor tp=TokenProcessor.getInstance(); String token=tp.generateToken(); request.getSession().setAttribute("token",token); //request.setAttribute("token",token); request.getRequestDispatcher("/session/form.jsp").forward(request,response); }
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doGet(request, response); }
}//Token令牌的意思class TokenProcessor{ private TokenProcessor(){} private static final TokenProcessor instance=new TokenProcessor(); public static TokenProcessor getInstance() { return instance; } public String generateToken(){ String token=System.currentTimeMillis()+new Random().nextInt()+""; try { MessageDigest md=MessageDigest.getInstance("md5"); //不管token有多大，都只会返回一个128位，16个长度 byte[] md5=md.digest(token.getBytes()); BASE64Encoder be=new BASE64Encoder(); return be.encode(md5); } catch (NoSuchAlgorithmException e) { throw new RuntimeException(e); } } }
验证用户是否正确：
public class form_01 extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setCharacterEncoding("UTF-8"); response.setContentType("text/html"); PrintWriter out = response.getWriter();// String name=request.getParameter("name");// String password=request.getParameter("password"); String token=request.getParameter("hidden1"); System.out.println(token); if(token!=null&&request.getSession(false).getAttribute("token").equals(token)){ System.out.println("用户注册......"); } else System.out.println("用户注册失败");
}
}
