Filter实现权限拦截
页面
- 登录页面 login.jsp
- 登录成功页面 /sys/success.jsp
- 登录失败页面 error.jsp
功能
输入用户名正确则登录成功进入 /sys/success.jsp
否则进入 error.jsp
利用session判断是否处于登录状态，有登录权限
若不处于则即便输入/sys/success.jsp 过滤器拦截跳转error.jsp
代码
JSP
login.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>登录</title>
</head>
<body>
<form action="servlet/login" method="post">
<input type="text" name="username">
<input type="submit">
</form>
</body>
</html>
success.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>主页</title>
</head>
<body>
<h1>成功进入主页</h1>
<p><a href="/servlet/logout">注销</a></p>
</body>
</html>
error.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>error</title>
</head>
<body>
<h1>登录失败</h1>
<p><a href="/servlet/logout">返回首页</a></p>
</body>
</html>
Servlet
login.java
package servlet;
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 doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String username = req.getParameter("username");
System.out.println(username);
req.getSession().setAttribute("user_session",req.getSession().getId());
if(username.equals("admin")){
resp.sendRedirect("/sys/success.jsp");
}
else{
resp.sendRedirect("/error.jsp");
}
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}
logout.java
package servlet;
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 doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
Object user_session = req.getSession().getAttribute("user_session");
if(user_session!=null){
// System.out.println(user_session);
req.getSession().removeAttribute("user_session");
}
resp.sendRedirect("/login.jsp");
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}
Filter
sysFiter.java
package Filter;
import javax.servlet.*;
import javax.servlet.http.HttpServlet;
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 servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
HttpServletRequest req = (HttpServletRequest) servletRequest;
HttpServletResponse resp = (HttpServletResponse) servletResponse;
if(req.getSession().getAttribute("user_session")==null)
{
resp.sendRedirect("/error.jsp");
}
filterChain.doFilter(servletRequest, servletResponse);
}
@Override
public void destroy() {
}
}
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>servlet.login</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>login</servlet-name>
<url-pattern>/servlet/login</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>logout</servlet-name>
<servlet-class>servlet.logout</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>logout</servlet-name>
<url-pattern>/servlet/logout</url-pattern>
</servlet-mapping>
<filter>
<filter-name>SysFilter</filter-name>
<filter-class>Filter.SysFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>SysFilter</filter-name>
<url-pattern>/sys/*</url-pattern>
</filter-mapping>
</web-app>