java_客户端防表单重复提交和服务器端session防表单重复提交

用户输入FormServlet链接

FormServlet-〉form.jsp->DoFormServlet

FormServlet:产生token，放在session中

form.jsp：hidden拿到token数据并一同提交到>DoFormServlet

DoFormServlet：检测是否重复提交表单

//FormServlet

//产生表单

public class FormServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)

			throws ServletException, IOException {

		//产生随机数，表单号

		TokenProcessor tp = TokenProcessor.getInstance();

		String token = tp.generateToken();

		request.getSession().setAttribute("token", token);

		request.getRequestDispatcher("/form.jsp").forward(request,response);

	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)

			throws ServletException, IOException {

		doGet(request,response);

	}

}

//随机数发生器

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");

			byte[] md5 = md.digest(token.getBytes());

			BASE64Encoder encode = new BASE64Encoder();

			return encode.encode(md5);

		} catch (NoSuchAlgorithmException e) {

			// TODO Auto-generated catch block

			throw new RuntimeException();

		}

	}

}

//form.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

  <head>

	<title>My jsp</title>

  </head>

  <body>

     <form action="/NANA/servlet/DoFormServlet" method="post">

     <input type="hidden" name="token" value="${token}">

     用户名:<input type="text" name="username"><br/>

     <input type="submit" value="提交">

     </form>

  </body>

</html>

DoFormServlet:

public class DoFormServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)

			throws ServletException, IOException {

		boolean b = isTokenValid(request);

		if(!b){

			System.out.println("submitted");

			return;

		}

		request.getSession().removeAttribute("token");

		System.out.println("success,insert user");

	}

	private boolean isTokenValid(HttpServletRequest request) {

		// TODO Auto-generated method stub

		String client_token = request.getParameter("token");

		if(client_token==null){

			return false;

		}

		String server_token = (String)request.getSession().getAttribute("token");

		if(server_token==null){

			return false;

		}

		if(!client_token.equalsIgnoreCase(server_token)){

			return false;

		}

		return true;

	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)

			throws ServletException, IOException {

		doGet(request,response);

	}

}

巴特西

java_客户端防表单重复提交和服务器端session防表单重复提交

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