过滤器(Filter)登录验证（无法跳过登录界面直接进入主页面）

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我是靠谱客的博主现代丝袜，最近开发中收集的这篇文章主要介绍过滤器(Filter)登录验证（无法跳过登录界面直接进入主页面），觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

效果图：
在这里插入图片描述

代码：
web.xml：

<filter>
  <filter-name>LoginCheckFilter</filter-name>
  <filter-class>text.web.filter.LoginCheckFilter</filter-class>
  </filter>
  <filter-mapping>
  <filter-name>LoginCheckFilter</filter-name>
  <url-pattern>/filter/*</url-pattern>
  </filter-mapping>

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="loginServlet" method="post">
姓名：<input type="text" name="username"/><br/>
密码：<input type="text" name="password"/><br/>
<input type="submit" value="提交"/>
</form>
</body>
</html>

main.jsp：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
这是主页面...
</body>
</html>

User.java：

package text.web.filter;

public class User {
	private String username;
	private String password;
	public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		this.username = username;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
	public User(String username, String password) {
		super();
		this.username = username;
		this.password = password;
	}
	public User() {
		
	}
	

}

LoginServlet.java：

package text.web.filter;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet{

	protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		String username = req.getParameter("username");
		String password = req.getParameter("password");
		
		if("rose".equals(username)&&"123".equals(password)) {
			HttpSession session = req.getSession();
			session.setAttribute("USER_IN_SESSION",new User(username,password));
			resp.sendRedirect("/day17/filter/main");
		}else {
			resp.sendRedirect("/day17/login.html");
		}
	}
	

}

LoginCheckFilter.java：

package text.web.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;
import javax.servlet.http.HttpSession;

public class LoginCheckFilter implements Filter{


	public void init(FilterConfig filterConfig) throws ServletException {
		
	}
	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
			throws IOException, ServletException {
		HttpServletRequest req=(HttpServletRequest)request;
		HttpServletResponse resp=(HttpServletResponse)response;
		HttpSession session = req.getSession();
		Object object = session.getAttribute("USER_IN_SESSION");
		if(object==null) {
			resp.sendRedirect("/day17/login.html");
			return;
		}else {
			chain.doFilter(req, resp);
		}
	}
    public void destroy() {
		
	}
}

MainServlet.java：

package text.web.filter;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/filter/main")
public class MainServlet extends HttpServlet{

	protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		req.getRequestDispatcher("/view/main.jsp").forward(req,resp);
		
	}
	

}