Java Spring-security@PreAuthorize-NullPointerException。为什么？

我试图实现对用户在控制器中角色的检查，这样当用户调用特定的web地址时，他就可以访问（或不访问）页面

因此，我将@PreAuthorize（“hasPermission…”）放在控制器的一个方法中，并创建了自定义的*PermissionEvaluator*。它将两个字符串作为参数（实体名称-字符串，权限名称-字符串），稍后我将从用户的角色对象中获取这些参数。出于测试目的，它总是返回true

问题：在放置@PreAuthorize时，我总是得到一个NullPointerException。您能解释一下我做错了什么吗

控制器

@RequestMapping(value = "goal/new", method = RequestMethod.GET)
@PreAuthorize("hasPermission('GOAL', 'WRITE')")
public String add (Model model,  RedirectAttributes redirect) {
   User user = AuthUtils.getCurrentUser();
   Goal goal = new Goal();
   Set<Unit> units = unitService.getUnitsByRole(user.getRoles());
   model.addAttribute("goal", goal);
   model.addAttribute("units", units);
return WEB_FORM_URL;
}

@Component
public class CustomPermissionEvaluator implements PermissionEvaluator {
    @Override
    public boolean hasPermission(Authentication authentication, Object targetDomainObject, Object permission) {
        System.out.println("Permission eveluator: called");
        boolean permissionGranted = true;
        return permissionGranted;
    }

    @Override
    public boolean hasPermission(Authentication authentication, Serializable serializable, String targetType,
                                 Object permission) {
        return false;
    }
}

全局方法安全配置

@Configuration
@EnableGlobalMethodSecurity(securedEnabled = true, prePostEnabled = true, jsr250Enabled = true, proxyTargetClass = true)
public class CustomMethodSecurityConfig extends GlobalMethodSecurityConfiguration {

    @Autowired
    CustomPermissionEvaluator permissionEvaluator;

    @Bean
    public MethodSecurityExpressionHandler methodSecurityExpressionHandler() {
        DefaultMethodSecurityExpressionHandler handler = new DefaultMethodSecurityExpressionHandler();
        handler.setPermissionEvaluator(permissionEvaluator);
        return handler;
    }
}

Errorstack

java.lang.NullPointerException: null
    at org.springframework.security.access.expression.SecurityExpressionRoot.hasPermission(SecurityExpressionRoot.java:177) ~[spring-security-core-5.1.4.RELEASE.jar:5.1.4.RELEASE]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_201]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_201]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_201]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_201]
    at org.springframework.expression.spel.support.ReflectiveMethodExecutor.execute(ReflectiveMethodExecutor.java:130) ~[spring-expression-5.1.5.RELEASE.jar:5.1.5.RELEASE]
    at org.springframework.expression.spel.ast.MethodReference.getValueInternal(MethodReference.java:138) ~[spring-expression-5.1.5.RELEASE.jar:5.1.5.RELEASE]
    at org.springframework.expression.spel.ast.MethodReference.getValueInternal(MethodReference.java:94) ~[spring-expression-5.1.5.RELEASE.jar:5.1.5.RELEASE]
    at org.springframework.expression.spel.ast.SpelNodeImpl.getTypedValue(SpelNodeImpl.java:114) ~[spring-expression-5.1.5.RELEASE.jar:5.1.5.RELEASE]
    at org.springframework.expression.spel.standard.SpelExpression.getValue(SpelExpression.java:300) ~[spring-expression-5.1.5.RELEASE.jar:5.1.5.RELEASE]
    at org.springframework.security.access.expression.ExpressionUtils.evaluateAsBoolean(ExpressionUtils.java:26) ~[spring-security-core-5.1.4.RELEASE.jar:5.1.4.RELEASE]
    at org.springframework.security.access.expression.method.ExpressionBasedPreInvocationAdvice.before(ExpressionBasedPreInvocationAdvice.java:59) ~[spring-security-core-5.1.4.RELEASE.jar:5.1.4.RELEASE]

---

我不是100%确定，但是您能否更改CustomMethodSecurityConfig中的方法签名，以实际覆盖GlobalMethodSecurityConfiguration中的正确方法

所以

而不是

  @Bean
    public MethodSecurityExpressionHandler methodSecurityExpressionHandler() {

---

将“@Override”添加到public MethodSecurityExpressionHandler而不是“@Bean”。现在我得到一个错误“method不重写或实现来自超类型的方法”。是的，因为您还需要更改方法名称以匹配。请确保将其称为“createExpressionHandler”有效。谢谢！

  @Bean
    public MethodSecurityExpressionHandler methodSecurityExpressionHandler() {