spring security注销导致NullPointerException

一段时间以来我一直在尝试了解 spring-security，除了logout方面。在查看有关 SO 的其他问题时，我觉得他们中的大多数人都面临着与会话未终止相关的问题。

另一方面，我面临着完全不同的麻烦。我的安全 XML 文件配置如下：

<http path-type="ant" auto-config="false" use-expressions="true"
    access-denied-page="/?login_error=2">
    <intercept-url pattern="/web/open/**" access="permitAll" />
    <intercept-url pattern="/web/**" access="isAuthenticated()" />

    <form-login login-processing-url="/static/j_spring_security_check"
        default-target-url="/web/base/view" always-use-default-target="true"
        login-page="/" authentication-failure-url="/?login_error=1" />

    <logout logout-url="/static/j_spring_security_logout"
        invalidate-session="true" logout-success-url="/" />
</http>

In my web.xml我已经映射了login controller到上下文根[使用welcome-file列表]，并且还具有所需的springSecurityFilterChain设置。现在登录操作完美运行。目标 JSP 有一个注销链接，如下所示：

<a href="<c:url value="/static/j_spring_security_logout"/>">Logout</a>

然而，每当我点击注销链接时，我都会收到可怕的消息NullPointerException。如果我在这里犯了一些明显的错误，有人可以告诉我吗？

异常堆栈：

java.lang.NullPointerException
    at java.util.Hashtable.get(Hashtable.java:334)
    at org.apache.tomcat.util.http.Parameters.getParameterValues(Parameters.java:116)
    at org.apache.tomcat.util.http.Parameters.getParameter(Parameters.java:127)
    at org.apache.catalina.connector.Request.getParameter(Request.java:1133)
    at org.apache.catalina.connector.RequestFacade.getParameter(RequestFacade.java:384)
    at javax.servlet.ServletRequestWrapper.getParameter(ServletRequestWrapper.java:140)
    at org.springframework.security.web.authentication.AbstractAuthenticationTargetUrlRequestHandler.determineTargetUrl(AbstractAuthenticationTargetUrlRequestHandler.java:86)
    at org.springframework.security.web.authentication.AbstractAuthenticationTargetUrlRequestHandler.handle(AbstractAuthenticationTargetUrlRequestHandler.java:67)
    at org.springframework.security.web.authentication.logout.SimpleUrlLogoutSuccessHandler.onLogoutSuccess(SimpleUrlLogoutSuccessHandler.java:28)
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:100)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:381)
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:79)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:381)
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:168)
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:237)

感谢您抽出宝贵的时间。

The determineTargetUrl中的方法AbstractAuthenticationTargetUrlRequestHandler似乎无法获取请求参数。对我来说通常可以提供一个defaultTargetUrl并设置alwaysUseDefaultTargetUrl to true这意味着determineTargetUrl始终返回给定的 URL 并防止 URL 确定魔法。

我会通过注册自己的来做到这一点LogoutSuccessHandler实施如：

<logout
    logout-url="/static/j_spring_security_logout"
    invalidate-session="true"
    success-handler-ref="myLogoutSuccessHandler" />

代替logout-success-url.

A LogoutSuccessHandler看起来很简单：

public class MyLogoutSuccessHandler extends AbstractAuthenticationTargetUrlRequestHandler implements LogoutSuccessHandler {

    @Override
    public void onLogoutSuccess(HttpServletRequest request, HttpServletResponse response, Authentication authentication throws IOException, ServletException {
        // maybe do some other things ...
        super.handle(request, response, authentication);
    }
}

将您的注销 URL 设置为defaultTargetUrl在为自定义定义 bean 时，在您的安全上下文中LogoutSuccessHandler:

<bean id="myLogoutSuccessHandler" class="foobar.impl.MyLogoutSuccessHandler">
    <property name="defaultTargetUrl" value="/" />
    <property name="alwaysUseDefaultTargetUrl" value="true" />
</bean>