以下文章将显示在我参与的一个项目中，我们如何使用Spring的AOP来介绍一些与安全性相关的功能。 这样的概念是为了使用户能够看到一些UI组件，他需要具有一定级别的安全特权。 如果不满足该要求，则不会显示UIComponent。 让我们看一下项目结构：

然后还有aopApplicationContext.xml：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"xmlns:context="http://www.springframework.org/schema/context"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:aop="http://www.springframework.org/schema/aop"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsdhttp://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsdhttp://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.1.xsdhttp://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd"><aop:aspectj-autoproxy /><context:annotation-config /><context:component-scan base-package="pl.grzejszczak.marcin.aop"><context:exclude-filter type="annotation" expression="org.aspectj.lang.annotation.Aspect"/></context:component-scan><bean class="pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor" factory-method="aspectOf"/> </beans>

现在，让我们看一下Spring应用程序上下文中最有趣的几行。 首先，我们拥有所有必需的模式-我认为不需要对此进行更深入的解释。 然后我们有：

<aop:aspectj-autoproxy/>

启用@AspectJ支持。 接下来是

<context:annotation-config />
<context:component-scan base-package="pl.grzejszczak.marcin.aop"><context:exclude-filter type="annotation" expression="org.aspectj.lang.annotation.Aspect"/>
</context:component-scan>

首先，我们通过注释打开Spring配置。 然后，我们故意排除了由Spring本身将其初始化为Bean的方面。 为什么？ 因为…

<bean class="pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor" factory-method="aspectOf"/>

我们希望自己创建方面，并提供factory-method =” aspectOf”。 这样，我们的方面将包含在我们的bean的自动装配过程中-因此，所有带有@Autowired注释的字段都将注入bean。 现在让我们继续执行代码：

UserServiceImpl.java

package pl.grzejszczak.marcin.aop.service;import org.springframework.stereotype.Service;import pl.grzejszczak.marcin.aop.type.Role;
import pl.grzejszczak.marcin.aop.user.UserHolder;@Service
public class UserServiceImpl implements UserService {private UserHolder userHolder;@Overridepublic UserHolder getCurrentUser() {return userHolder;}@Overridepublic void setCurrentUser(UserHolder userHolder) {this.userHolder = userHolder;}@Overridepublic Role getUserRole() {if (userHolder == null) {return null;}return userHolder.getUserRole();}
}

UserServiceImpl类正在模仿一种服务，该服务将从数据库或当前应用程序上下文中获取当前用户信息。

UserHolder.java

package pl.grzejszczak.marcin.aop.user;import pl.grzejszczak.marcin.aop.type.Role;public class UserHolder {private Role userRole;public UserHolder(Role userRole) {this.userRole = userRole;}public Role getUserRole() {return userRole;}public void setUserRole(Role userRole) {this.userRole = userRole;}
}

这是一个简单的持有人类，其中包含有关当前用户角色的信息。

角色.java

package pl.grzejszczak.marcin.aop.type;public enum Role {ADMIN("ADM"), WRITER("WRT"), GUEST("GST");private String name;private Role(String name) {this.name = name;}public static Role getRoleByName(String name) {for (Role role : Role.values()) {if (role.name.equals(name)) {return role;}}throw new IllegalArgumentException("No such role exists [" + name + "]");}public String getName() {return this.name;}@Overridepublic String toString() {return name;}
}

角色是一个枚举，它为管理员 ， 作家或来宾定义了一个角色。

UIComponent.java

package pl.grzejszczak.marcin.aop.ui;public abstract class UIComponent {protected String componentName;protected String getComponentName() {return componentName;}}

一些UI组件的具体实现的抽象。

SomeComponentForAdminAndGuest.java

package pl.grzejszczak.marcin.aop.ui;import pl.grzejszczak.marcin.aop.annotation.SecurityAnnotation;
import pl.grzejszczak.marcin.aop.type.Role;@SecurityAnnotation(allowedRole = { Role.ADMIN, Role.GUEST })
public class SomeComponentForAdminAndGuest extends UIComponent {public SomeComponentForAdminAndGuest() {this.componentName = "SomeComponentForAdmin";}public static UIComponent getComponent() {return new SomeComponentForAdminAndGuest();}
}

此组件是UI组件扩展的示例，只有拥有Admin或Guest角色的用户才能看到。

SecurityAnnotation.java

package pl.grzejszczak.marcin.aop.annotation;import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;import pl.grzejszczak.marcin.aop.type.Role;@Retention(RetentionPolicy.RUNTIME)
public @interface SecurityAnnotation {Role[] allowedRole();
}

定义可以创建此组件的角色的注释。

UIFactoryImpl.java

package pl.grzejszczak.marcin.aop.ui;import org.apache.commons.lang.NullArgumentException;
import org.springframework.stereotype.Component;@Component
public class UIFactoryImpl implements UIFactory {@Overridepublic UIComponent createComponent(Class<? extends UIComponent> componentClass) throws Exception {if (componentClass == null) {throw new NullArgumentException("Provide class for the component");}return (UIComponent) Class.forName(componentClass.getName()).newInstance();}
}

给定扩展UIComponent的对象类的工厂类将返回给定UIComponent的新实例。

SecurityInterceptor.java

package pl.grzejszczak.marcin.aop.interceptor;import java.lang.annotation.Annotation;
import java.lang.reflect.AnnotatedElement;
import java.util.Arrays;
import java.util.List;import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;import pl.grzejszczak.marcin.aop.annotation.SecurityAnnotation;
import pl.grzejszczak.marcin.aop.service.UserService;
import pl.grzejszczak.marcin.aop.type.Role;
import pl.grzejszczak.marcin.aop.ui.UIComponent;@Aspect
public class SecurityInterceptor {private static final Logger LOGGER = LoggerFactory.getLogger(SecurityInterceptor.class);public SecurityInterceptor() {LOGGER.debug("Security Interceptor created");}@Autowiredprivate UserService userService;@Pointcut("execution(pl.grzejszczak.marcin.aop.ui.UIComponent pl.grzejszczak.marcin.aop.ui.UIFactory.createComponent(..))")private void getComponent(ProceedingJoinPoint thisJoinPoint) {}@Around("getComponent(thisJoinPoint)")public UIComponent checkSecurity(ProceedingJoinPoint thisJoinPoint) throws Throwable {LOGGER.info("Intercepting creation of a component");Object[] arguments = thisJoinPoint.getArgs();if (arguments.length == 0) {return null;}Annotation annotation = checkTheAnnotation(arguments);boolean securityAnnotationPresent = (annotation != null);if (securityAnnotationPresent) {boolean userHasRole = verifyRole(annotation);if (!userHasRole) {LOGGER.info("Current user doesn't have permission to have this component created");return null;}}LOGGER.info("Current user has required permissions for creating a component");return (UIComponent) thisJoinPoint.proceed();}/*** Basing on the method's argument check if the class is annotataed with* {@link SecurityAnnotation}* * @param arguments* @return*/private Annotation checkTheAnnotation(Object[] arguments) {Object concreteClass = arguments[0];LOGGER.info("Argument's class - [{}]", new Object[] { arguments });AnnotatedElement annotatedElement = (AnnotatedElement) concreteClass;Annotation annotation = annotatedElement.getAnnotation(SecurityAnnotation.class);LOGGER.info("Annotation present - [{}]", new Object[] { annotation });return annotation;}/*** The function verifies if the current user has sufficient privilages to* have the component built* * @param annotation* @return*/private boolean verifyRole(Annotation annotation) {LOGGER.info("Security annotation is present so checking if the user can use it");SecurityAnnotation annotationRule = (SecurityAnnotation) annotation;List<Role> requiredRolesList = Arrays.asList(annotationRule.allowedRole());Role userRole = userService.getUserRole();return requiredRolesList.contains(userRole);}
}

这是在执行函数createComponent的切入点处定义的方面
UIFactory接口。 在“ 环绕” 建议中，存在一种逻辑，该逻辑首先检查将什么样的参数传递给方法createComponent（例如SomeComponentForAdminAndGuest.class）。 接下来，检查此类是否用SecurityAnnotation进行注释，如果是，它将检查创建组件所需的角色类型。 然后，它检查当前用户（从UserService到UserHolder的Roles）是否具有呈现组件所需的角色。 如果是这样的话 调用thisJoinPoint.proceed（），实际上返回扩展UIComponent的类的对象。 现在让我们对其进行测试-SpringJUnit4ClassRunner来了

AopTest.java

package pl.grzejszczak.marcin.aop;import org.junit.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;import pl.grzejszczak.marcin.aop.service.UserService;
import pl.grzejszczak.marcin.aop.type.Role;
import pl.grzejszczak.marcin.aop.ui.SomeComponentForAdmin;
import pl.grzejszczak.marcin.aop.ui.SomeComponentForAdminAndGuest;
import pl.grzejszczak.marcin.aop.ui.SomeComponentForGuest;
import pl.grzejszczak.marcin.aop.ui.SomeComponentForWriter;
import pl.grzejszczak.marcin.aop.ui.UIFactory;
import pl.grzejszczak.marcin.aop.user.UserHolder;@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = { "classpath:aopApplicationContext.xml" })
public class AopTest {@Autowiredprivate UIFactory uiFactory;@Autowiredprivate UserService userService;@Testpublic void adminTest() throws Exception {userService.setCurrentUser(new UserHolder(Role.ADMIN));Assert.assertNotNull(uiFactory.createComponent(SomeComponentForAdmin.class));Assert.assertNotNull(uiFactory.createComponent(SomeComponentForAdminAndGuest.class));Assert.assertNull(uiFactory.createComponent(SomeComponentForGuest.class));Assert.assertNull(uiFactory.createComponent(SomeComponentForWriter.class));}
}

和日志：

pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor:26 Security Interceptor created
pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor:38 Intercepting creation of a component
pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor:48 Argument's class - [[class pl.grzejszczak.marcin.aop.ui.SomeComponentForAdmin]]
pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor:54 Annotation present - [@pl.grzejszczak.marcin.aop.annotation.SecurityAnnotation(allowedRole=[ADM])]
pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor:57 Security annotation is present so checking if the user can use it
pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor:70 Current user has required permissions for creating a component
pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor:38 Intercepting creation of a component
pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor:48 Argument's class - [[class pl.grzejszczak.marcin.aop.ui.SomeComponentForAdminAndGuest]]
pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor:54 Annotation present - [@pl.grzejszczak.marcin.aop.annotation.SecurityAnnotation(allowedRole=[ADM, GST])]
pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor:57 Security annotation is present so checking if the user can use it
pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor:70 Current user has required permissions for creating a component
pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor:38 Intercepting creation of a component
pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor:48 Argument's class - [[class pl.grzejszczak.marcin.aop.ui.SomeComponentForGuest]]
pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor:54 Annotation present - [@pl.grzejszczak.marcin.aop.annotation.SecurityAnnotation(allowedRole=[GST])]
pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor:57 Security annotation is present so checking if the user can use it
pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor:66 Current user doesn't have permission to have this component created
pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor:38 Intercepting creation of a component
pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor:48 Argument's class - [[class pl.grzejszczak.marcin.aop.ui.SomeComponentForWriter]]
pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor:54 Annotation present - [@pl.grzejszczak.marcin.aop.annotation.SecurityAnnotation(allowedRole=[WRT])]
pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor:57 Security annotation is present so checking if the user can use it
pl.grzejszczak.marcin.aop.interceptor.SecurityInterceptor:66 Current user doesn't have permission to have this component created

单元测试表明，对于给定的Admin角色，仅创建了前两个组件，而对于其他两个，则返回null（由于用户没有适当的权限）。 这就是在我们的项目中，我们如何使用Spring的AOP创建一个简单的框架，该框架将检查用户是否可以创建给定的组件。 由于对这些方面进行了编程，因此不必记住编写任何与安全相关的代码，因为它将为他完成。

翻译自: https://www.javacodegeeks.com/2013/04/spring-aop-in-security-controlling-creation-of-ui-components-via-aspects.html