java 使用 Spring 授权标签检查用户是否登录时出错？
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Error using Spring authorize tag to check to see if user is logged in?
提问by SJS
Trying to test to see if a user is logged in I am using the following code:
尝试测试以查看用户是否已登录我正在使用以下代码：
<%@ taglib prefix="sec" uri="http://www.springframework.org/security/tags" %>
<sec:authorize access="isAuthenticated()">
YES, you are logged in!
</sec:authorize>
But I am getting the following erorr?
但我收到以下错误？
javax.servlet.jsp.JspException: No visible WebSecurityExpressionHandler instance could be found in the application context. There must be at least one in order to support expressions in JSP 'authorize' tags.
at org.springframework.security.taglibs.authz.AuthorizeTag.getExpressionHandler(AuthorizeTag.java:100)
at org.springframework.security.taglibs.authz.AuthorizeTag.authorizeUsingAccessExpression(AuthorizeTag.java:58)
at org.springframework.security.taglibs.authz.AuthorizeTag.doStartTag(AuthorizeTag.java:48)
回答by John
Setting use-expressions="true" in the http element will work but means all your security settings in both Java code and security contexts must use expression notations. This can be a problem if you are currently using the standard security notations.
在 http 元素中设置 use-expressions="true" 会起作用，但这意味着 Java 代码和安全上下文中的所有安全设置都必须使用表达式符号。如果您当前使用的是标准安全符号，这可能是一个问题。
To use both expressions and standard notations just declare a new bean in your security context like so -
要同时使用表达式和标准符号，只需在您的安全上下文中声明一个新的 bean，就像这样 -
<beans:bean class="org.springframework.security.web.access.expression.DefaultWebSecurityExpressionHandler"/>
回答by Philipp Hügelmeyer
To use expressions to secure individual URLs, you would first need to set the use-expressions attribute in the element to true
要使用表达式来保护单个 URL，您首先需要将元素中的 use-expressions 属性设置为 true
<http use-expressions="true">See Spring Security doc
<http use-expressions="true">请参阅 Spring Security 文档
