Question

有没有办法，如何确定使用Spring 3 MVC + Spring security时是否有人已登录？这是我的安全背景：

<beans xmlns:security="http://www.springframework.org/schema/security"
   xmlns="http://www.springframework.org/schema/beans"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://www.springframework.org/schema/beans
             http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
             http://www.springframework.org/schema/security
             http://www.springframework.org/schema/security/spring-security-3.1.xsd">

<security:http pattern="/resources/**" security="none"/>
<security:http pattern="/login*" security="none" auto-config="true"/>
<security:http pattern="/denied" security="none"/>

<security:http auto-config="true" access-denied-page="/denied" servlet-api-provision="false">
    <security:intercept-url pattern="/login*" access="IS_AUTHENTICATED_ANONYMOUSLY"/>
    <security:intercept-url pattern="/edit/**" access="ROLE_EDIT"/>
    <security:intercept-url pattern="/admin/**" access="ROLE_ADMIN"/>
    <security:intercept-url pattern="/**" access="ROLE_USER"/>
    <security:form-login login-page="/login"  authentication-failure-url="/denied"
                         default-target-url="/"/>
    <security:logout/>
</security:http>

<security:authentication-manager>
    <security:authentication-provider>
        <security:user-service>
            <security:user name="adam" password="adampassword" authorities="ROLE_USER"/>
            <security:user name="jane" password="janepassword" authorities="ROLE_USER, ROLE_ADMIN"/>
            <security:user name="sue" password="suepassword" authorities="ROLE_USER, ROLE_EDIT"/>
        </security:user-service>
    </security:authentication-provider>
</security:authentication-manager>

</beans>

我可以通过

在主页上确定它

<%
    User user = (User) SecurityContextHolder.getContext()
            .getAuthentication().getPrincipal();
    String username = user.getUsername();
%>

然而，在登录页面上它会生成nullpointer异常..： - /

当有人已经登录并且有人试图再次登录时，浏览器会转到myurl.com/home页面，我收到404错误，因为正确的地址应该只是myurl.com/。当没有人登录时，浏览器会重定向到正确的地址。任何想法可能是一个错误？

我的jsp页面：

<%@ page import="org.springframework.security.core.userdetails.User"%>
<%@ page import="org.springframework.security.core.context.SecurityContextHolder"%>
<%@ page import="java.util.Collection"%>
<%@ page import="javax.swing.text.AbstractDocument"%>
<%@ page import="org.springframework.security.core.GrantedAuthority"%>

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
</head>
<body>
<div class="form">
    <form name="f" action="j_spring_security_check" method="post">
        <input type="text" id="username" class="input-block-level"
            name="j_username" placeholder="Username"> <input
            type="password" id="password" name="j_password"
            class="input-block-level" placeholder="Password">
        <button class="btn btn-large btn-primary" type="submit">Sign
            in</button>
    </form>
</div>
</body>
</html>

Answer 1

Spring Security包含一个JSP标记库，可以通过下一个代码导入：

<%@ taglib prefix="sec" uri="http://www.springframework.org/security/tags" %>

使用导入的，您可以使用jsp标签“sec”（用于安全性），

 <sec:authorize access="isAuthenticated()">
     ... <!-- Code or message to show when user is authenticated -->
 </sec:authorize>

在标记内，您可以运行某些代码，显示标记或HTML。

http://static.springsource.org/spring-security/site/docs/3.0.x/reference/taglibs.html

Answer 2

在jsp中你可以使用

第一个问题：

 <sec:authorize access="isAuthenticated()">
     the user has logged in 
 </sec:authorize>

第二个问题：

当某个已登录的机构直接请求登录页面时，您会收到404错误，因为您限制了对此页面的访问权限：

 <security:intercept-url pattern="/login*" access="IS_AUTHENTICATED_ANONYMOUSLY"/>

一种解决方案是使用permitAll访问限制，并在jsp中为已经登录的用户发布一些通知：

 <security:intercept-url pattern="/login*" access="permitAll"/>

的login.jsp

 <sec:authorize access="isAuthenticated()">
     you already logged in. 
 </sec:authorize>

如何在登录页面上确定是否有某些用户已经登录？

2 个答案: