利用过滤器实现以下功能:
? ? ? ? ①用户登陆之后 向Session中放入用户的数据
? ? ? ? ②进入主页的时候判断用户是否已经登录 在过滤器中实现
1.过滤器?SysFilter.java
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class SysFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
@Override
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain filterChain) throws IOException, ServletException {
//HttpServletRequest req 和 ServletRequest servletRequest 是父子关系
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) resp;
if(request.getSession().getAttribute("USER_SESSION")==null){
response.sendRedirect("/error.jsp");
}
filterChain.doFilter(request,response);
}
@Override
public void destroy() {
}
}
2.登录页面 login.java
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class login extends HttpServlet {
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req,resp);//达到复用的效果
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//获取前端请求的参数
String username = req.getParameter("username");
String password = req.getParameter("password");
if(username.equals("root")&&password.equals("root")){//登录成功
req.getSession().setAttribute("USER_SESSION",req.getSession().getId());
resp.sendRedirect("/sys/success.jsp");
}else{
resp.sendRedirect("/error.jsp");
}
}
}
3.退出 logout.java
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class logout extends HttpServlet {
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req,resp);//达到复用的效果
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
Object user_session = req.getSession().getAttribute("USER_SESSION");
if(user_session!=null){
req.getSession().removeAttribute("USER_SESSION");
resp.sendRedirect("/login.jsp");
}
}
}
web.xml文件配置
<?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_4_0.xsd"
version="4.0"
metadata-complete="true">
<servlet>
<servlet-name>login</servlet-name>
<servlet-class>com.demo.servlet.login</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>login</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>logout</servlet-name>
<servlet-class>com.demo.servlet.logout</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>logout</servlet-name>
<url-pattern>/logout</url-pattern>
</servlet-mapping>
<filter>
<filter-name>Sysfilter</filter-name>
<filter-class>com.demo.Filter.SysFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>Sysfilter</filter-name>
<url-pattern>/sys/*</url-pattern>
</filter-mapping>
</web-app>
登录页面 login.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>登录</title>
</head>
<body>
<form action="/login" method="post">
username<input type="text" name="username"><br>
password<input type="password" name="password"><br>
<input type="submit">
</form>
</body>
</html>
登录成功 success.jsp
<%--
Created by IntelliJ IDEA.
User: 13604
Date: 2022/5/13
Time: 16:29
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>主页</title>
</head>
<body>
<p><a href="/logout">注销</a></p>
</body>
</html>
登录失败 error.jsp
<%--
Created by IntelliJ IDEA.
User: 13604
Date: 2022/5/13
Time: 16:29
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>404</title>
</head>
<body>
<a href="/login.jsp">返回登录页面</a>
</body>
</html>
pom.xml配置
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.example</groupId>
<artifactId>javaweb-login</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>war</packaging>
<dependencies>
<!-- Servlet依赖-->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
</dependency>
<!-- Jsp依赖-->
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>javax.servlet.jsp-api</artifactId>
<version>2.3.3</version>
</dependency>
<!-- JSTL表达式的依赖-->
<dependency>
<groupId>javax.servlet.jsp.jstl</groupId>
<artifactId>jstl-api</artifactId>
<version>1.2</version>
</dependency>
<!-- standard标签库-->
<dependency>
<groupId>taglibs</groupId>
<artifactId>standard</artifactId>
<version>1.1.2</version>
</dependency>
<!-- 链接数据库-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.47</version>
</dependency>
</dependencies>
</project>
?
