圆通AI助手带你掌握Spring AOP面向切面编程核心技术

public class UserServiceImpl implements UserService {
    
    private static final Logger logger = LoggerFactory.getLogger(UserServiceImpl.class);
    
    @Override
    public void register(User user) {
        // 日志记录
        logger.info("开始执行注册方法，参数：{}", user);
        long start = System.currentTimeMillis();
        
        // 权限校验
        if (!hasPermission(user)) {
            logger.error("权限不足");
            throw new SecurityException("权限不足");
        }
        
        // 核心业务逻辑
        System.out.println("执行注册业务逻辑");
        
        // 事务管理
        try {
            // 模拟事务提交
            System.out.println("提交事务");
        } catch (Exception e) {
            System.out.println("回滚事务");
        }
        
        // 性能监控
        long end = System.currentTimeMillis();
        logger.info("注册方法执行耗时：{}ms", end - start);
    }
}

@Aspect
@Component
public class LoggingAspect {
    
    // 切点（Pointcut）：定义"在哪里做"
    @Pointcut("execution( com.example.service..(..))")
    public void serviceMethods() {}
    
    // 通知（Advice）：定义"做什么"
    @Before("serviceMethods()")
    public void logBeforeMethod(JoinPoint joinPoint) {
        System.out.println("方法执行前：" + joinPoint.getSignature().getName());
    }
}

// 静态代理示例：中介代理房屋交易
public class HouseProxy implements HouseSubject {
    private HouseSubject realSubject;
    
    @Override
    public void saleHouse() {
        System.out.println("[中介] 前置审核逻辑");
        realSubject.saleHouse();      // 调用真实业务
        System.out.println("[中介] 后置处理逻辑");
    }
}

@Service
public class UserService {
    public void register(String username) {
        System.out.println("【日志】开始执行register方法");
        long start = System.currentTimeMillis();
        try {
            System.out.println("【核心业务】用户注册：" + username);
        } catch (Exception e) {
            System.out.println("【异常处理】注册失败");
        }
        long end = System.currentTimeMillis();
        System.out.println("【监控】register耗时：" + (end - start) + "ms");
    }
}

<!-- Maven -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-aop</artifactId>
</dependency>

package com.example.aspect;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.;
import org.springframework.stereotype.Component;

@Aspect          // ① 声明这是一个切面类
@Component       // ② 将切面类纳入Spring容器管理
public class PerformanceAspect {
    
    // ③ 定义切点：匹配service包下所有类的所有方法
    @Pointcut("execution( com.example.service..(..))")
    public void serviceMethods() {}
    
    // ④ 环绕通知：统计方法执行耗时
    @Around("serviceMethods()")
    public Object measureTime(ProceedingJoinPoint joinPoint) throws Throwable {
        long start = System.currentTimeMillis();
        String methodName = joinPoint.getSignature().toShortString();
        
        // 前置增强逻辑
        System.out.println("【Before】开始执行：" + methodName);
        
        Object result = joinPoint.proceed();  // ⑤ 执行目标方法，关键调用！
        
        // 后置增强逻辑
        long end = System.currentTimeMillis();
        System.out.println("【After】执行完成：" + methodName + "，耗时：" + (end - start) + "ms");
        
        return result;
    }
}

@Service
public class UserService {
    public void register(String username) {
        // 只有核心业务，横切逻辑全部交给AOP处理
        System.out.println("用户注册：" + username);
    }
}

【Before】开始执行：UserService.register(String)
用户注册：张三
【After】执行完成：UserService.register(String)，耗时：2ms

public class MiniAOP {
    public static Object getProxy(Object target) {
        return Proxy.newProxyInstance(
            target.getClass().getClassLoader(),
            target.getClass().getInterfaces(),
            new InvocationHandler() {
                @Override
                public Object invoke(Object proxy, Method method, Object[] args) 
                        throws Throwable {
                    System.out.println("【Before】方法执行前增强");
                    Object result = method.invoke(target, args);  // 反射调用原始方法
                    System.out.println("【After】方法执行后增强");
                    return result;
                }
            }
        );
    }
}