详解SpringBoot AOP 拦截器（Aspect注解方式）

下面是详解 SpringBoot AOP 拦截器（Aspect 注解方式）的完整攻略，并附带两条示例。

什么是 AOP

AOP（Aspect Oriented Programming，面向切面编程）是一种面向对象编程的编程思想，AOP 的思想是将系统分解为多个功能单元，称之为“切面”（Aspect），然后编写代码来定义这些切面。这些切面可以跨越多个类，不仅仅是某个类的某个方法。AOP 主要用于解决系统中的横切关注点（Crosscutting Concerns）问题，比如日志记录、性能统计、安全控制、事务处理等。

什么是 SpringBoot AOP 拦截器（Aspect 注解方式）

SpringBoot AOP 在 AOP 基础上，采用了拦截器的方式来实现对方法的切面编程。SpringBoot AOP 拦截器可以根据注解设置来实现不同的切面，常见的切面有：

• @Before：在方法之前执行。
• @After：在方法之后执行。
• @AfterReturning：在方法正常返回之后执行。
• @AfterThrowing：在方法抛出异常之后执行。

SpringBoot AOP 拦截器（Aspect 注解方式）的实现步骤

下面是 SpringBoot AOP 拦截器（Aspect 注解方式）的实现步骤：

步骤一：创建一个自定义注解

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface Log {
    String value() default "";
}

步骤二：编写 AOP 切面代码

@Aspect
@Component
@Slf4j
public class LogAspect {
    @Around("@annotation(com.example.demo.annotation.Log)")
    public Object logRecord(ProceedingJoinPoint proceedingJoinPoint) throws Throwable {
        Object result = null;
        try {
            // 方法执行前
            String className = proceedingJoinPoint.getTarget().getClass().getName();
            String methodName = proceedingJoinPoint.getSignature().getName();
            log.info("Class Name: {}, Method Name：{}", className, methodName);
            Object[] args = proceedingJoinPoint.getArgs();
            for (Object arg : args) {
                log.info("Args: {}", arg);
            }
            result = proceedingJoinPoint.proceed(args);
            // 方法正常返回
            log.info("Result：{}", result);
        } catch (Throwable throwable) {
            // 方法执行异常
            log.error("Method Execution Error：{}", throwable.getMessage());
            throw throwable;
        }
        return result;
    }
}

步骤三：在需要切面的方法上添加自定义注解

@RestController
public class UserController {
    @Autowired
    private UserService userService;

    @Log(value = "查询用户信息")
    @GetMapping("/user/get/{id}")
    public UserVO getUserById(@PathVariable("id") Long id) {
        return userService.getUserById(id);
    }
}

示例一：记录用户操作日志

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface UserOperateLog {
    String value() default "";
}

@Aspect
@Component
@Slf4j
public class UserOperateLogAspect {
    @Autowired
    private UserOperateLogService userOperateLogService;

    @Around("@annotation(com.example.demo.annotation.UserOperateLog)")
    public Object userOperateLogRecord(ProceedingJoinPoint proceedingJoinPoint) throws Throwable {
        Object result = null;
        try {
            // 方法执行前
            MethodSignature signature = (MethodSignature) proceedingJoinPoint.getSignature();
            UserOperateLog userOperateLogAnn = signature.getMethod().getAnnotation(UserOperateLog.class);
            String operation = userOperateLogAnn.value();
            String className = proceedingJoinPoint.getTarget().getClass().getName();
            String methodName = proceedingJoinPoint.getSignature().getName();
            log.info("Class Name: {}, Method Name：{}, Operation: {}", className, methodName, operation);

            // 记录用户操作日志
            User user = SessionUtils.getCurrentUser();
            if (user != null) {
                UserOperateLog userOperateLog = new UserOperateLog();
                userOperateLog.setUserId(user.getId());
                userOperateLog.setUserName(user.getName());
                userOperateLog.setOperation(operation);
                userOperateLog.setOperateTime(new Date());
                userOperateLogService.saveUserOperateLog(userOperateLog);
            }

            Object[] args = proceedingJoinPoint.getArgs();
            result = proceedingJoinPoint.proceed(args);
            // 方法正常返回
            log.info("Result：{}", result);
        } catch (Throwable throwable) {
            // 方法执行异常
            log.error("Method Execution Error：{}", throwable.getMessage());
            throw throwable;
        }
        return result;
    }
}

@RestController
public class UserController {
    @Autowired
    private UserService userService;

    @UserOperateLog(value = "查询用户信息")
    @GetMapping("/user/get/{id}")
    public UserVO getUserById(@PathVariable("id") Long id) {
        return userService.getUserById(id);
    }
}

示例二：时间统计

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface TimeCount {
    String value() default "";
}

@Aspect
@Component
@Slf4j
public class TimeCountAspect {

    @Around("@annotation(com.example.demo.annotation.TimeCount)")
    public Object timeCount(ProceedingJoinPoint proceedingJoinPoint) throws Throwable {
        Object result = null;
        try {
            // 方法执行前
            MethodSignature signature = (MethodSignature) proceedingJoinPoint.getSignature();
            TimeCount timeCountAnn = signature.getMethod().getAnnotation(TimeCount.class);
            String operation = timeCountAnn.value();
            long startTime = System.currentTimeMillis();
            result = proceedingJoinPoint.proceed();
            long endTime = System.currentTimeMillis();
            log.info("Operation: {}，TimeCost: {}ms", operation, endTime - startTime);
        } catch (Throwable throwable) {
            // 方法执行异常
            log.error("Method Execution Error：{}", throwable.getMessage());
            throw throwable;
        }
        return result;
    }
}

@RestController
public class UserController {
    @Autowired
    private UserService userService;

    @TimeCount(value = "查询用户信息")
    @GetMapping("/user/get/{id}")
    public UserVO getUserById(@PathVariable("id") Long id) {
        return userService.getUserById(id);
    }
}

以上就是详解 SpringBoot AOP 拦截器（Aspect 注解方式）的完整攻略以及两条示例。