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" "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">
<!-- 定义版本 -->
<tlib-version>1.0</tlib-version>
<!-- 定义名字 -->
<short-name>apsliyuan</short-name>
<!-- 定义uri -->
<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""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。