1、 自動(dòng)登錄

http://blog.csdn.net/xj626852095/article/details/16825659

2. 防止表單重復(fù)提交

表單Servlet?

//負(fù)責(zé)產(chǎn)生表單 public class FormServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html;charset=UTF-8");PrintWriter out = response.getWriter();String token = TokenProccessor.getInstance().makeToken();request.getSession().setAttribute("token", token); //在服務(wù)器端保存隨機(jī)數(shù)out.println("<form action='/day07/servlet/DoFormServlet' method='post'>");out.write("<input type='hidden' name='token' value='"+token+"'>");out.println("用戶名:<input type='text' name='username'>");out.println("<input type='submit' value='提交'>");out.println("</form>");}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);} }class TokenProccessor{/**單態(tài)設(shè)計(jì)模式（保證類的對(duì)象在內(nèi)存中只有一個(gè)）*1、把類的構(gòu)造函數(shù)私有*2、自己創(chuàng)建一個(gè)類的對(duì)象*3、對(duì)外提供一個(gè)公共的方法，返回類的對(duì)象* */private TokenProccessor(){}private static final TokenProccessor instance = new TokenProccessor();public static TokenProccessor getInstance(){return instance;}public String makeToken(){ //checkException// 7346734837483 834u938493493849384 43434384String token = (System.currentTimeMillis() + new Random().nextInt(999999999)) + "";//數(shù)據(jù)指紋 128位長(zhǎng) 16個(gè)字節(jié) md5try {MessageDigest md = MessageDigest.getInstance("md5");byte md5[] = md.digest(token.getBytes());//base64編碼--任意二進(jìn)制編碼明文字符 adfsdfsdfsfBASE64Encoder encoder = new BASE64Encoder();return encoder.encode(md5);} catch (NoSuchAlgorithmException e) {throw new RuntimeException(e);}}} 表單處理Servlet

public class DoFormServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {boolean b = isToken(request); //判斷用戶是否是重復(fù)提交if(b==true){System.out.println("請(qǐng)不要重復(fù)提交");return;}request.getSession().removeAttribute("token");System.out.println("處理用戶提交請(qǐng)求！！");}private boolean isToken(HttpServletRequest request) {String client_token = request.getParameter("token");if(client_token==null){return true;}String server_token = (String) request.getSession().getAttribute("token");if(server_token==null){return true;}if(!client_token.equals(server_token)){return true;}return false;}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}}

轉(zhuǎn)載于:https://www.cnblogs.com/xj626852095/p/3648071.html

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