为什么在装饰器中调用安全认证属性“principal.displayName”会抛出异常？

调用安全认证属性是否有原因principal.displayName在装饰器中会引起问题吗？

我将其设置为 sitemesh 装饰器中的变量：

                <c:set var="displayName">
                    <sec:authentication property="principal.displayName" />
                </c:set>

但它会产生这个异常：

java.lang.RuntimeException: javax.servlet.ServletException: javax.servlet.jsp.JspException: Invalid property 'principal.displayName' o
f bean class [org.springframework.security.authentication.AnonymousAuthenticationToken]: Bean property 'principal.displayName' is not
readable or has an invalid getter method: Does the return type of the getter match the parameter type of the setter?
        at com.opensymphony.sitemesh.webapp.decorator.BaseWebAppDecorator.render(BaseWebAppDecorator.java:39)
        at com.opensymphony.sitemesh.webapp.SiteMeshFilter.doFilter(SiteMeshFilter.java:84)
        at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
        at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
        at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
        at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
        at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
        at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
        at com.google.apphosting.utils.jetty.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:70)
        at org.mortbay.jetty.servlet.Dispatcher.forward(Dispatcher.java:327)
        at org.mortbay.jetty.servlet.Dispatcher.forward(Dispatcher.java:126)
        at org.tuckey.web.filters.urlrewrite.NormalRewrittenUrl.doRewrite(NormalRewrittenUrl.java:195)
        at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java:159)
        at org.tuckey.web.filters.urlrewrite.RuleChain.doRules(RuleChain.java:141)
        at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest(UrlRewriter.java:90)
        at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:417)
        at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)

您的要求Authentication此时的对象是AnonymousAuthenticationToken http://static.springsource.org/spring-security/site/docs/3.0.x/apidocs/org/springframework/security/authentication/AnonymousAuthenticationToken.html类，并且该类没有名为的属性displayName.

显然，SpringSecurity 认为用户没有登录。你可能需要

• 更改访问规则，以便只有在用户登录时才能查看该 JSP，或者

• 将 JSP 更改为如下所示（假设您使用的是 Spring 3.0.x 并且已启用 Web 安全表达式）。

<c:set var="displayName">
    <sec:authorize access="isAuthenticated()">
        <sec:authentication property="principal.displayName" />
    </sec:authorize>
</c:set>

参考：

• 基于表达式的访问控制 http://static.springsource.org/spring-security/site/docs/3.0.x/reference/el-access.html
• JSP 标签库 http://static.springsource.org/spring-security/site/docs/3.0.x/reference/taglibs.html