JSP使用自定义标签防止表单重复提交的方法

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");
    }
  }
}

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="";
    try {
      pageContext.getOut().print(html);
    } catch (IOException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
    return EVAL_BODY_INCLUDE;
  }
}

<&＃63;xml version="1.0" encoding="UTF-8" &＃63;>

  
  1.0
  
  apsliyuan
  
  http://my.oschina.net/aps
  
    loginTokenTag
    cn.itcast.apsliyuan.tag.LoginTokenTag
    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"%>







  
    
    
  

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
  }
}

<&＃63;xml version="1.0" encoding="UTF-8"&＃63;>

  Tag
  
    index.html
    index.htm
    index.jsp
    default.html
    default.htm
    default.jsp
  
  
    loginServlet
    cn.itcast.apsliyuan.web.servlet.LoginServet
  
  
    loginServlet
    /server/Login
  
  
    UncodeFilter
    cn.itcast.apsliyuan.filter.UncodeFilter
  
  
    UncodeFilter
    /*