IDEA SpringBoot 添加AOP(面向切面编程)

1.AOP(Aspect Oriented Programming)相关术语

①增强处理(Advice)

• 前置增强
• 后置增强
• 环绕增强
• 异常抛出增强
• 最终增强等类型

②切入点(Pointcut)

• 何时执行切面类代码

③连接点(Joint Point)

④切面(Aspect)

• 非核心代码,如日志,异常等,单独取出作为切面类

⑤目标对象(Target Object)

• Service服务层

⑥AOP代理(AOP Proxy)

⑦织入(Weaving)

• 即往目标对象中注入切面类的说法

2.关于execution表达式的规定,来源于Spring官网

The following examples show some common pointcut expressions:
下面的示例显示了一些常见的切入点表达式:

The execution of any public method:
执行任何公共方法：

execution(public * *(..))

The execution of any method with a name that begins with set:
执行名称以set开头的任何方法：

execution(* set*(..))

The execution of any method defined by the AccountService interface:
AccountService接口定义的任何方法的执行：

execution(* com.xyz.service.AccountService.*(..))

The execution of any method defined in the service package:
执行服务包中定义的任何方法：

execution(* com.xyz.service.*.*(..))

The execution of any method defined in the service package or one of its sub-packages:
执行服务包或其子包之一中定义的任何方法：

execution(* com.xyz.service..*.*(..))

3.SpringBoot实现AOP

①在SpringBoot工程基础上添加Aop依赖

	<!--AOP面向切面编程-->
    <dependency>
    	<groupId>org.springframework.boot</groupId>
    	<artifactId>spring-boot-starter-aop</artifactId>
    </dependency>

②创建Service类,即目标对象

IUserService接口类

	public interface IUserService {
    /**
     * 用于测试前置通知,后置通知及环绕通知
     */
    void aopTest();

    /**
     * 用户测试后置通知返回值
     * @return
     */
    String aopReturning();

    /**
     * 用于测试后置通知异常返回
     * @throws Exception
     */
    void aopExceptionTest() throws Exception;
}

UserServiceImpl实现类

	@Override
    public void aopTest(){
        System.out.println("用来测试AOP功能");
    }

    @Override
    public String aopReturning() {
        return "返回值";
    }

    @Override
    public void aopExceptionTest() throws Exception {
        throw new Exception("AOP后置异常测试");
    }

③创建AOP类

@Component
@Aspect
public class MyAspect {
    /**
     * 切点前置通知
     */
    @Before("execution(* com.cx.springboot.service..*.*(..))")
    public void before() {
        System.out.println("前置通知");
    }

    /**
     * 切点后置通知
     */
    @After("execution(* com.cx.springboot.service..*.*(..))")
    public void after() {
        System.out.println("后置通知");
    }

    /**
     * 切点环绕通知
     *
     * @param proceedingJoinPoint
     * @return
     * @throws Throwable
     */
    @Around("execution(* com.cx.springboot.service..*.*(..))")
    public Object around(ProceedingJoinPoint proceedingJoinPoint) throws Throwable {
        System.out.println("====环绕开始====");
        // 切面中获取到调用方法名
        String methodName = proceedingJoinPoint.getSignature().getName();
        // 切面中获取到调用方法的参数
        Object[] args = proceedingJoinPoint.getArgs();

        // 执行调用方法
        Object result = proceedingJoinPoint.proceed();

        System.out.println("方法名:" + methodName);
        System.out.println("方法参数:" + args.toString());

        System.out.println("====环绕结束====");

        return result;
    }

    /**
     * 切点后置通知返回值
     *
     * @param joinPoint
     * @param result
     */
    @AfterReturning(pointcut = "execution(* com.cx.springboot.service..*.*(..))", returning = "result")
    public void afterReturning(JoinPoint joinPoint, String result) {
        System.out.println("后置通知返回值:" + result);
    }

    /**
     * 切点后置通知异常返回
     *
     * @param joinPoint
     * @param exception
     */
    @AfterThrowing(pointcut = "execution(* com.cx.springboot.service..*.*(..))",throwing = "exception")
    public void afterThrowing(JoinPoint joinPoint, Exception exception) {
        System.out.println("后置异常返回:" + exception.getMessage());
    }
    
}	

④创建测试AOP类

	@SpringBootTest
	public class UserTest {
    	@Autowired
    	IUserService userService;
    	@Test
    	public void test01(){
        	userService.aopTest();
    	}

    	@Test
    	public void test02(){
        	userService.aopReturning();
    	}

    	@Test
    	public void test03(){
        	try {
            	userService.aopExceptionTest();
        	} catch (Exception e) {
            	System.out.println("异常结束");
        	}
		}

⑤测试结果

• 前置通知
  
• 后置通知
  
• 环绕通知
  
• 后置通知返回值
  
• 后置通知异常返回