使用Spring Security'hasPermission()'对未经授权的REST服务请求返回JSON


问题内容

我正在使用Spring安全性实现方法级别的限制/授权(在 REST服务上 )。
我已使用spring表达式语言并实现了自定义Expression Evaluator。

对我来说很好。但是,如果未经授权的用户尝试访问该服务,它将以登录页面作为响应。由于我的应用程序 仅基于REST
,因此我只想为所有请求返回JSON数据。

我如何让它返回而不是登录页面JSON?(例如:{status : Denied}

这是代码段:

CustomEvaluator

public boolean hasPermission(Authentication authentication, Object userId, Object permissionId) {
        List<String> permList = new MyDAO().getPermissionsForUser((String) userId);
        if(permList.contains(((String) permissionId))){
            return true;
        }else{
            return false;
        }
    }

服务

@PreAuthorize("hasPermission(#userId, '3')")
    public String testAuthorization(Object obj, String userId){

        System.out.println("Has access to the service method....");

        return  "success";
    }

控制者

public @ResponseBody String testAuthorization(Object o,@RequestParam("userId") String userId){
        System.out.println("User ID = "+userId);
        String abc = service.testAuthorization(o,userId);
        return "{\"status\":\"success\"}";
    }

spring-security.xml

<?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/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-3.0.xsd">


    <security:global-method-security secured-annotations="enabled" pre-post-annotations="enabled">
        <security:expression-handler ref="expressionHandler"/>
    </security:global-method-security>

    <!-- This is where we configure Spring-Security  -->
    <security:http auto-config="true" use-expressions="true" access-denied-page="/auth/auth/denied" >
        <security:intercept-url pattern="/auth/auth/login" access="permitAll"/>
        <security:intercept-url pattern="/auth/main/admin" access="hasRole('ROLE_ADMIN')"/>
        <security:intercept-url pattern="/auth/main/common" access="hasRole('ROLE_USER')"/>


    </security:http>

    <security:authentication-manager>
        <security:authentication-provider user-service-ref="customUserDetailsService">
            <security:password-encoder ref="passwordEncoder"/>
        </security:authentication-provider>
    </security:authentication-manager>

    <!-- Use a Md5 encoder since the user's passwords are stored as Md5 in the database -->
    <bean class="org.springframework.security.authentication.encoding.Md5PasswordEncoder" id="passwordEncoder"/>

    <!-- A custom service where Spring will retrieve users and their corresponding access levels  -->
    <bean id="customUserDetailsService" class="com.cjl.security.service.CustomUserDetailsService"/>

    <bean id="expressionHandler" class="org.springframework.security.access.expression.method.DefaultMethodSecurityExpressionHandler">
        <property name="permissionEvaluator" ref="permissionEvaluator"/>
    </bean>

    <bean id="permissionEvaluator" class="com.cjl.security.evaluators.MethodPermissionEvaluator"/>


</beans>

问题答案:

发生了什么事AccessDeniedException,因此您想要配置系统以拦截该异常并返回JSON。

您可以@ExceptionHandler在控制器中设置捕获的方法AccessDeniedException。但是,您可能想在所有控制器中执行相同的操作,因此,如果您使用的是Spring
3.2,则可以@ControllerAdvice在单独的“ advice”类上使用批注,然后@ExceptionHandler在其中包含方法。

@ControllerAdvice 
public class ExceptionControllerAdvice {

    @ExceptionHandler(AccessDeniedException.class)
    @ResponseBody
    public String exception(AccessDeniedException e) {
        return "{\"status\":\"access denied\"}";
    } 
}