本文实例讲述了JSP使用自定义标签防止表单重复提交的方法。分享给大家供大家参考。具体如下：
1. 编写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.HttpServletResponse; public class LoginServet extends HttpServlet { /** * 反序列化 */ private static final long serialVersionUID = 4960707156159691747L; @Override public void doPost(HttpServletRequest requset, HttpServletResponse response) throws ServletException, IOException { // 获得输入框中的值 String token = requset.getParameter("tokenName"); // 获得session中的值 String sessionToken = (String) requset.getSession().getAttribute( "token"); if (token.equals(sessionToken)) { response.getWriter().print("保存成功"); requset.getSession().removeAttribute("token");//为了保证session中的值不重复，所以移除 } else { response.getWriter().print("对不起不能重复提交"); } } }
2. 编写自定义标签的类：
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 LoginTokenTag extends TagSupport{ /** * 凡序列化 */ private static final long serialVersionUID = -1815168785364991254L; @Override public int doStartTag() throws JspException { // TODO Auto-generated method stub //得到uuid String uuid=UUID.randomUUID().toString().replace("-",""); //得到session,pageContext 是域对象同样也是工具类 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. 编写×.tld文件：
<"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"> <> <tlib-version>1.0</tlib-version> <> <short-name>apsliyuan</short-name> <> <uri>http://my.oschina.net/aps</uri> <tag> <name>loginTokenTag</name> <tag-class>cn.itcast.apsliyuan.tag.LoginTokenTag</tag-class> <body-content>JSP</body-content> </tag> </taglib>
4. jsp中的代码：
<%@ 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"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>index.jsp</title> </head> <body> <form action="${pageContext.request.contextPath}/server/Login" method="post"> <aps:loginTokenTag/> <input type="submit" value="Login"/> </form> </body> </html>
5. 防止乱码的拦截器：
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("拦截完成"); } 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. web.xml中的配置：
<"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>
希望本文所述对大家的JSP程序设计有所帮助。
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