JSP使用自定义标签防止表单重复提交的方法

前端技术 2023/09/02 JSP

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：

<?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\">
  <!-- 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：

<?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>

希望本文所述对大家的JSP程序设计有所帮助。

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