认证Filter实战

本文链接： https://blog.csdn.net/chengqiuming/article/details/100585648

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

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