上机指导第十一章

最新推荐文章于 2023-05-12 13:43:40 发布

原创最新推荐文章于 2023-05-12 13:43:40 发布

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#java #前端 #servlet

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该文章展示了如何使用JavaServletFilter实现登录验证，特别是阻止以“T”开头的用户名登录，这些用户将被重定向到错误页面，而其他用户则会进入欢迎界面。过滤器配置在/chkuser请求路径上生效。

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完成登录验证的程序设计：设计一个过滤器，过滤用户名以“T”开头的用户名登录，使其登录到错误页面，其他则正确登录到成功界面。

package com.inspur.filter;

import java.io.IOException;

import javax.servlet.Filter;

import javax.servlet.FilterChain;

import javax.servlet.FilterConfig;

import javax.servlet.RequestDispatcher;

import javax.servlet.ServletException;

import javax.servlet.ServletRequest;

import javax.servlet.ServletResponse;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class loginFilter implements Filter {

/**

* 【案例】禁止从本机浏览器访问web资源的success.jsp页面

public void destroy() {

}

public void doFilter(ServletRequest request, ServletResponse response,

FilterChain filterChain) throws IOException, ServletException {

HttpServletResponse resp = (HttpServletResponse) response;

HttpServletRequest req = (HttpServletRequest) request;

// 接收页面录入的用户名

String uname = (String) req.getParameter("username");

// 用户名以“T”开头的用户名登录，登录到错误页面，其他用户登录到欢迎界面

if (uname != null && uname.startsWith("T")) {

resp.sendRedirect("/CH11_LAB/error.jsp");

} else {

resp.sendRedirect("/CH11_LAB/welcome.jsp?username=" + uname);

}

public void init(FilterConfig filterConfig) throws ServletException {

}

<%@ page language="java" pageEncoding="UTF-8"%>

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

<html>

<head>

</head>

<body>

Object error = request.getAttribute("loginError");

if (error != null) {

}

用户名：

<br>

密    码：

<br>

</form>

</body>

</html>

<%@ page language="java" pageEncoding="UTF-8"%>

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

<html>

<head>

</head>

<body>

欢迎您：<%=request.getParameter("username") %><br>

</body>

</html>

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

<head>

<title>My JSP 'filterDemo01.jsp' starting page</title>

</head>

<body>

对不起，您输入的用户名或密码有误！

</body>

</html>

<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"

version="3.1">

<filter-name>loginFilter</filter-name>

<filter-class>com.inspur.filter.loginFilter</filter-class>

</filter>

<filter-mapping>

<filter-name>loginFilter</filter-name>

<url-pattern>/chkuser</url-pattern>

</filter-mapping>

</web-app>