JSP uses custom tags to prevent repeated submission of forms. jsp forms
This example describes how JSP uses custom tags to prevent repeated submission of forms. Share it with you for your reference. The details are as follows:
1. Write servelt:
Package cn. itcast. apsliyuan. web. servlet; import java. io. IOException; import javax. servlet. servletException; import javax. servlet. http. httpServlet; import javax. servlet. http. httpServletRequest; import javax. servlet. http. extends; public class LoginServet extends HttpServlet {/*** deserialization */private static final long serialVersionUID = complete; @ Override public void doPost (HttpServletRequest requset, HttpServletResponse response) throws ServletException, IOException {// obtain the value String token = requset in the input box. getParameter ("tokenName"); // obtain the value String sessionToken = (String) requset in the session. getSession (). getAttribute ("token"); if (token. equals (sessionToken) {response. getWriter (). print ("saved successfully"); requset. getSession (). removeAttribute ("token"); // remove} else {response. getWriter (). print ("sorry, you cannot submit it again ");}}}
2. Compile a custom label class:
Package cn. itcast. apsliyuan. tag; import java. io. IOException; import java. util. UUID; import javax. servlet. jsp. jspException; import javax. servlet. jsp. tagext. tagSupport; public class logtailkentag extends TagSupport {/*** all serializing */private static final long serialVersionUID =-1815168785364991254L; @ Override public int doStartTag () throws JspException {// TODO Auto-generated method stub // obtain uuid String uuid = UUID. randomUUID (). toString (). replace ("-", ""); // get the session. pageContext is a domain object and also a tool class pageContext. getSession (). setAttribute ("token", uuid); String html = "<input type = 'text' name = 'tokenname' readonly = 'readonly' value =" + uuid + "> "; try {pageContext. getOut (). print (html);} catch (IOException e) {// TODO Auto-generated catch block e. printStackTrace ();} return EVAL_BODY_INCLUDE ;}}
3. Compile the X. tld file:
<? Xml version = "1.0" encoding = "UTF-8"?> <Taglib xmlns = "http://java.sun.com/xml/ns/javaee" xmlns: xsi = "http://www.w3.org/2001/XMLSchema-instance" xsi: schemaLocation = "http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd" version = "2.1"> <! -- Define version --> <tlib-version> 1.0 </tlib-version> <! -- Define the name --> <short-name> apsliyuan </short-name> <! -- Define uri --> <uri> http://my.oschina.net/aps </uri> <tag> <name> logtailkentag </name> <tag-class> cn. itcast. apsliyuan. tag. logtailkentag </tag-class> <body-content> JSP </body-content> </tag> </taglib>
4. Code in jsp:
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@taglib uri="http://my.oschina.net/aps" prefix="aps" %> <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">5. Anti-garbled Interceptor:
Package cn. itcast. apsliyuan. filter; import java. io. IOException; import javax. servlet. filter; import javax. servlet. filterChain; import javax. servlet. filterConfig; import javax. servlet. servletException; import javax. servlet. servletRequest; import javax. servlet. servletResponse; import javax. servlet. http. httpServletRequest; import javax. servlet. http. httpServletResponse; public class UncodeFilter implements Filter {public void init (FilterConfig filterConfig) throws ServletException {// TODO Auto-generated method stub System. out. println ("intercepted");} public void doFilter (ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {HttpServletRequest request = (HttpServletRequest) req; httpServletResponse response = (HttpServletResponse) res; request. setCharacterEncoding ("UTF-8"); response. setContentType ("text/html; charset = UTF-8"); chain. doFilter (request, response);} public void destroy () {// TODO Auto-generated method stub }}6. configuration in web. xml:
<?xml version="1.0" encoding="UTF-8"?><web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5"> <display-name>Tag</display-name> <welcome-file-list> <welcome-file>index.html</welcome-file> <welcome-file>index.htm</welcome-file> <welcome-file>index.jsp</welcome-file> <welcome-file>default.html</welcome-file> <welcome-file>default.htm</welcome-file> <welcome-file>default.jsp</welcome-file> </welcome-file-list> <servlet> <servlet-name>loginServlet</servlet-name> <servlet-class>cn.itcast.apsliyuan.web.servlet.LoginServet</servlet-class> </servlet> <servlet-mapping> <servlet-name>loginServlet</servlet-name> <url-pattern>/server/Login</url-pattern> </servlet-mapping> <filter> <filter-name>UncodeFilter</filter-name> <filter-class>cn.itcast.apsliyuan.filter.UncodeFilter</filter-class> </filter> <filter-mapping> <filter-name>UncodeFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping></web-app>I hope this article will help you with JSP program design.
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