Java教程
18-filter实现权限拦截
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18-filter实现权限拦截
概述
本文主要是一个利用filter实现权限拦截的代码实践
我们通过http://localhost:8080/login.jsp 登录页面通过输入admin用户名可以访问登录成功页面
其他均会返回失败页面，并且无法通过http://localhost:8080/sys/success.jsp 直接访问成功页面
实践
web/error.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1>错误</h1>
<h3>没有权限或用户名错误</h3>
</body>
</html>
web/index.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>$Title$</title>
</head>
<body>
$END$
</body>
</html>
web/login.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<form action="/s9/servlet/login" method="post">
用户名<input type="text" name="username"><hr>
<input type="submit">
</form>
</body>
</html>
web/sys/login.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1>主页</h1>
<p><a href="/servlet/logout">注销</p>
</body>
</html>
web/WEB_INF/web.xml
<?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">
<servlet>
<servlet-name>login</servlet-name>
<servlet-class>com.kuang.servlet.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>login</servlet-name>
<url-pattern>/s9/servlet/login</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>logout</servlet-name>
<servlet-class>com.kuang.servlet.LogoutServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>logout</servlet-name>
<url-pattern>/servlet/logout</url-pattern>
</servlet-mapping>
<filter>
<filter-name>sysFliter</filter-name>
<filter-class>com.kuang.filter.SysFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>sysFliter</filter-name>
<url-pattern>/sys/*</url-pattern>
</filter-mapping>
</web-app>
LoginServlet.java
package com.kuang.servlet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
/**
* 功能描述
*
* @since 2022-08-26
*/
public class LoginServlet extends HttpServlet {
@Override protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// 获取前端请求参数
String username = req.getParameter("username");
if (username.equals("admin")){
System.out.println("aa");
req.getSession().setAttribute("USER_SESSION",req.getSession().getId());
// req.getRequestDispatcher("/sys/success.jsp").forward(req, resp);
// 跳转采用重定向
resp.sendRedirect("/sys/success.jsp");
} else{
System.out.println("bb");
// req.getRequestDispatcher("/error.jsp").forward(req, resp);
resp.sendRedirect("/error.jsp");
}
}
@Override protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
doGet(req, resp);
}
}
LogoutServlet.java
package com.kuang.servlet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
/**
* 功能描述
*
* @since 2022-08-30
*/
public class LogoutServlet extends HttpServlet {
@Override protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
Object userSession = req.getSession().getAttribute("USER_SESSION");
if (userSession!=null) {
req.getSession().removeAttribute("USER_SESSION");
System.out.println("removed");
}
// req.getRequestDispatcher("/login.jsp").forward(req, resp);
resp.sendRedirect("/login.jsp");
}
@Override protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
doGet(req, resp);
}
}
SysFilter.java
package com.kuang.filter;
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 java.io.IOException;
/**
* 功能描述
*
* @since 2022-08-31
*/
public class SysFilter implements Filter {
@Override public void init(FilterConfig filterConfig) throws ServletException {
Filter.super.init(filterConfig);
}
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) servletRequest;
HttpServletResponse response = (HttpServletResponse) servletResponse;
if(request.getSession().getAttribute("USER_SESSION")==null){
response.sendRedirect("/error.jsp");
}
filterChain.doFilter(servletRequest,servletResponse);
}
@Override public void destroy() {
Filter.super.destroy();
}
}
pom
<?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">
<parent>
<artifactId>JavaWeb-Study</artifactId>
<groupId>org.example</groupId>
<version>1.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>09-Filter2</artifactId>
<properties>
<maven.compiler.source>8</maven.compiler.source>
<maven.compiler.target>8</maven.compiler.target>
</properties>
</project>
父pom
<?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-Study</artifactId>
<packaging>pom</packaging>
<version>1.0-SNAPSHOT</version>
<modules>
<module>01-HelloServlet</module>
<module>02-ServletContext</module>
<module>03-Download</module>
<module>04-VerificationCode</module>
<module>05-Login</module>
<module>06-Cookie</module>
<module>07-Session</module>
<module>08-Filter</module>
<module>09-Filter2</module>
</modules>
<properties>
<maven.compiler.source>8</maven.compiler.source>
<maven.compiler.target>8</maven.compiler.target>
</properties>
<dependencies>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>4.0.1</version>
</dependency>
<!-- https://mvnrepository.com/artifact/javax.servlet.jsp/javax.servlet.jsp-api -->
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>javax.servlet.jsp-api</artifactId>
<version>2.3.3</version>
</dependency>
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>jsp-api</artifactId>
<version>2.2</version>
</dependency>
<dependency>
<groupId>org.apache.tomcat</groupId>
<artifactId>jasper</artifactId>
<version>6.0.53</version>
</dependency>
</dependencies>
</project>
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