认证Filter实战

小鱼儿 2021-07-24 23:20 363阅读 0赞

**一 定义认证Filter**

package lee;
    
    import javax.servlet.*;
    import javax.servlet.http.*;
    import javax.servlet.annotation.*;
    
    import java.io.*;
    
    @WebFilter(filterName="authority"
        , urlPatterns={"/*"}
        , initParams={
            @WebInitParam(name="encoding", value="GBK"),
            @WebInitParam(name="loginPage", value="/login.jsp"),
            @WebInitParam(name="proLogin", value="/proLogin.jsp")})
    public class AuthorityFilter implements Filter
    {
        // FilterConfig可用于访问Filter的配置信息
        private FilterConfig config;
        // 实现初始化方法
        public void init(FilterConfig config)
        {
            this.config = config;
        }
        // 实现销毁方法
        public void destroy()
        {
            this.config = null;
        }
        // 执行过滤的核心方法
        public void doFilter(ServletRequest request,
            ServletResponse response, FilterChain chain)
            throws IOException,ServletException
        {
            // 获取该Filter的配置参数
            String encoding = config.getInitParameter("encoding");
            String loginPage = config.getInitParameter("loginPage");
            String proLogin = config.getInitParameter("proLogin");
            // 设置request编码用的字符集
            request.setCharacterEncoding(encoding);            // ①
            HttpServletRequest requ = (HttpServletRequest)request;
            HttpSession session = requ.getSession(true);
            // 获取客户请求的页面
            String requestPath = requ.getServletPath();
            // 如果session范围的user为null，即表明没有登录
            // 且用户请求的既不是登录页面，也不是处理登录的页面
            if( session.getAttribute("user") == null
                && !requestPath.endsWith(loginPage)
                && !requestPath.endsWith(proLogin))
            {
                // forward到登录页面
                request.setAttribute("tip" , "您还没有登录");
                request.getRequestDispatcher(loginPage)
                    .forward(request, response);
            }
            // "放行"请求
            else
            {
                chain.doFilter(request, response);
            }
        }
    }

**二 视图**

1 login.jsp

<%@ page contentType="text/html; charset=GBK" language="java" errorPage="" %>
    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
        "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    <html xmlns="http://www.w3.org/1999/xhtml">
    <head>
        <title>登录页面</title>
        <meta name="website" content="http://www.crazyit.org" />
    </head>
    <body>
    <h2>登录页面</h2>
    <%
    if(request.getAttribute("tip") != null)
    {
        out.println("<font color='red'>"
            + request.getAttribute("tip")
            + "</font>");
    }
    %>
    <form method="post" action="proLogin.jsp">
    用户名:<input type="text" name="name"/><br/>
    <input type="submit" value="登录"/>
    </form>
    </body>
    </html>

2 proLogin.jsp

<%@ page contentType="text/html; charset=GBK" language="java" errorPage="" %>
    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
        "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    <html xmlns="http://www.w3.org/1999/xhtml">
    <head>
        <title> 登录页面 </title>
        <meta name="website" content="http://www.crazyit.org" />
    </head>
    <body>
    <h2>登录页面</h2>
    <%
    session.setAttribute("user"
        , request.getParameter("name"));
    %>
    登录成功，可以访问该应用的其他页面
    </body>
    </html>

**三 测试**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70 1][]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70]: /images/20210724/d3238649ade74e5084e39c2a8be4f88b.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70 1]: /images/20210724/df8b6e10f8244b9688a2de119a14272c.png