狂神说 javaweb 27集：Filter 实现权限拦截
作者：互联网
27，Filter 实现权限拦截
用户登录之后才能进入主页！用户注销后就不能进入主页了！
-
用户登录之后，向Sesison中放入用户的数据
-
进入主页的时候要判断用户是否已经登录；要求：在过滤器中实现！
login.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1>登录页面</h1>
<form action="/servlet/login" method="get">
用户名:<input type="text" name="username"> <br>
<input type="submit"name="登录">
</form>
</body>
</html>
LoginServelt.java
public class LoginServelt extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//获取前端的参数
String username = req.getParameter( "username" );
if (username.equals( "admin" )){//登录成功
req.getSession( ).setAttribute( Constant.USER_SESSION,req.getSession().getId());
resp.sendRedirect( "/sys/success.jsp" );
}else{//登录失败
resp.sendRedirect( "/error.jsp" );
}
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet( req, resp );
}
}
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，用户错误</h3>
<a href="/login.jsp">返回登录页面</a>
</body>
</html>
success.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<%--
<%
Object user_session = request.getSession().getAttribute( "USER_SESSION" );
if(user_session == null){
response.sendRedirect( "/login.jsp" );
}
%>
--%>
<h1>主页</h1>
<p><a href="/servlet/logout">注销</a></p>
</body>
</html>
LogoutServlet.java
public class LogoutServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
Object user_session = req.getSession().getAttribute( Constant.USER_SESSION );
if (user_session != null){
req.getSession().removeAttribute( Constant.USER_SESSION );
resp.sendRedirect( "/login.jsp" );
}else{
resp.sendRedirect( "/login.jsp" );
}
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet( req, resp );
}
}
SysFilter.java
public class SysFilter implements Filter {
public void init(FilterConfig filterConfig) throws ServletException {
}
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
/* if (req.getSession( ).setAttribute( Constant.USER_SESSION).level ==VIP1){
response.sendRedirect( "/vip1.jsp" );
}
if (req.getSession( ).setAttribute( Constant.USER_SESSION).level ==VIP2){
response.sendRedirect( "/vip2.jsp" );
}
if (req.getSession( ).setAttribute( Constant.USER_SESSION).level ==VIP3){
response.sendRedirect( "/vip3.jsp" );
}*/
//ServletRequest HttpServletRequest
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) resp;
Object user_session = request.getSession().getAttribute( Constant.USER_SESSION);
if (request.getSession().getAttribute( Constant.USER_SESSION) == null){
response.sendRedirect( "/error.jsp" );
}
chain.doFilter( request,response );
}
public void destroy() {
}
}
xml
<servlet>
<servlet-name>LoginServelt</servlet-name>
<servlet-class>com.study.servlet.LoginServelt</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServelt</servlet-name>
<url-pattern>/servlet/login</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>LogoutServlet</servlet-name>
<servlet-class>com.study.servlet.LogoutServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LogoutServlet</servlet-name>
<url-pattern>/servlet/logout</url-pattern>
</servlet-mapping>
<filter>
<filter-name>SysFilter</filter-name>
<filter-class>com.study.filter.SysFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>SysFilter</filter-name>
<!--只要是/servlet的任何请求，会经过这个过滤器，都会被过滤-->
<url-pattern>/sys/*</url-pattern>
</filter-mapping>
标签：getSession,27,javaweb,resp,req,Filter,SESSION,jsp,USER 来源： https://www.cnblogs.com/jianchizuo/p/16299455.html