为什么在Spring Security中对“匿名用户”进行身份验证？

Question

package org.demian.demibox.controllers;

import org.springframework.security.core.Authentication;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@Controller
public class MainController {
    private String getUsername() {
        Authentication auth = SecurityContextHolder.getContext().getAuthentication();
        if (auth.isAuthenticated())
            return auth.getName();
        else
            return null;
    }
    @RequestMapping(value = "/", method = RequestMethod.GET)
    public String showHome() {
        String username = getUsername();
        System.out.println(username);
        if (username == null || username.length() == 0)
            return "welcome";
        return "index";
    }
}

这是我的security-context.xml文件：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:security="http://www.springframework.org/schema/security"
    xsi:schemaLocation="http://www.springframework.org/schema/security http://www.springframework.org/schema/security/spring-security-3.2.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
    <security:authentication-manager>
        <security:authentication-provider>
            <security:jdbc-user-service data-source-ref="dataSource" id="jdbcUserService" />
            <!-- <security:password-encoder ref="passwordEncoder" /> -->
        </security:authentication-provider>
    </security:authentication-manager>
    <security:http use-expressions="true">
        <security:intercept-url pattern="/" access="permitAll" />
        <security:intercept-url pattern="/login" access="permitAll" />
        <security:intercept-url pattern="/redeem" access="permitAll" />
        <security:intercept-url pattern="/redeem_code" access="permitAll" />
        <security:intercept-url pattern="/static/**" access="permitAll" />
        <security:intercept-url pattern="/*" access="isAuthenticated()" />
        <security:intercept-url pattern="/**" access="isAuthenticated()" />
        <security:intercept-url pattern="/**" access="denyAll" />
        <security:form-login login-page="/login" authentication-failure-url="/login?error=true" />
        <security:logout logout-success-url="/" />
        <security:remember-me key="offersAppKey" user-service-ref="jdbcUserService" />
    </security:http>
    <security:global-method-security secured-annotations="enabled" />
    <!-- <bean id="passwordEncoder" class="org.springframework.security.crypto.password.StandardPasswordEncoder" /> -->
</beans>

以下行位于web.xml文件中：

<filter>
    <display-name>springSecurityFilterChain</display-name>
    <filter-name>springSecurityFilterChain</filter-name>
    <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
</filter>
<filter-mapping>
    <filter-name>springSecurityFilterChain</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

我正在通过Maven使用Tomcat8.0和所有最新的依赖项。

Answer 1

这就是spring-security默认情况下的工作方式。

从文档中：

注意，“匿名身份验证”的用户和未经身份验证的用户之间没有真正的概念上的区别。Spring Security的匿名身份验证为您配置访问控制属性提供了更方便的方法。例如，对servlet API调用（如GetCallerPrincipal)的调用仍将返回null，即使SecurityContextHolder中实际上存在匿名身份验证对象。