?
// 使用BeanFactory
Resource resource = new ClassPathResource("applicationContext.xml");
BeanFactory factory = new XmlBeanFactory(resource);
UserService userService = (UserService) factory.getBean("userService");

?

// 使用ApplicationContext
ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
UserService userService = context.getBean(UserService.class);

@Service
public class UserService {
    private final UserDao userDao;
    
    // 構造器注入
    @Autowired
    public UserService(UserDao userDao) {
        this.userDao = userDao;
    }
}

@Service
public class UserService {
    private UserDao userDao;
    
    // Setter方法注入
    @Autowired
    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }
}

@Service
public class UserService {
    // 字段注入
    @Autowired
    private UserDao userDao;
}

// 1. 定義切面
@Aspect
@Component
public class LoggingAspect {

// 2. 定義切點：匹配com.example.service包下所有類的所有方法
@Pointcut("execution(* com.example.service.*.*(..))")
public void serviceMethods() {}

// 3. 定義前置通知
@Before("serviceMethods()")
public void logBefore(JoinPoint joinPoint) {
    String methodName = joinPoint.getSignature().getName();
    Object[] args = joinPoint.getArgs();
    System.out.println("調用方法: " + methodName + ", 參數: " + Arrays.toString(args));
}

// 4. 定義后置通知
@After("serviceMethods()")
public void logAfter(JoinPoint joinPoint) {
    String methodName = joinPoint.getSignature().getName();
    System.out.println("方法" + methodName + "執(zhí)行完畢");
}

// 5. 定義返回通知
@AfterReturning(pointcut = "serviceMethods()", returning = "result")
public void logAfterReturning(JoinPoint joinPoint, Object result) {
    String methodName = joinPoint.getSignature().getName();
    System.out.println("方法" + methodName + "返回結果: " + result);
}

// 6. 定義異常通知
@AfterThrowing(pointcut = "serviceMethods()", throwing = "ex")
public void logAfterThrowing(JoinPoint joinPoint, Exception ex) {
    String methodName = joinPoint.getSignature().getName();
    System.out.println("方法" + methodName + "拋出異常: " + ex.getMessage());
}

// 7. 定義環(huán)繞通知
@Around("serviceMethods()")
public Object logAround(ProceedingJoinPoint joinPoint) throws Throwable {
    String methodName = joinPoint.getSignature().getName();
    
    // 方法執(zhí)行前
    long startTime = System.currentTimeMillis();
    
    // 執(zhí)行目標方法
    Object result = joinPoint.proceed();
    
    // 方法執(zhí)行后
    long endTime = System.currentTimeMillis();
    System.out.println("方法" + methodName + "執(zhí)行時間: " + (endTime - startTime) + "ms");
    
    return result;
}

}
啟用AOP支持：
@Configuration
@ComponentScan(“com.example”)
@EnableAspectJAutoProxy // 啟用AOP支持
public class AppConfig {
}

com.example
├── config
│ └── AppConfig.java // 配置類
├── dao
│ ├── UserDao.java // 數據訪問接口
│ └── UserDaoImpl.java // 數據訪問實現
├── service
│ ├── UserService.java // 業(yè)務服務接口
│ └── UserServiceImpl.java // 業(yè)務服務實現
├── aspect
│ └── LoggingAspect.java // 日志切面
└── Main.java // 主程序

// UserDao.java
public interface UserDao {
void addUser(String username);
String getUserById(int id);
}

// UserDaoImpl.java
@Repository
public class UserDaoImpl implements UserDao {
@Override
public void addUser(String username) {
System.out.println("數據庫中添加用戶: " + username);
}

@Override
public String getUserById(int id) {
    System.out.println("從數據庫中查詢ID為" + id + "的用戶");
    return "用戶" + id; // 模擬查詢結果
}

// UserService.java
public interface UserService {
void registerUser(String username);
String getUserInfo(int id);
}

// UserServiceImpl.java
@Service
public class UserServiceImpl implements UserService {
private final UserDao userDao;

// 構造器注入
@Autowired
public UserServiceImpl(UserDao userDao) {
    this.userDao = userDao;
}

@Override
public void registerUser(String username) {
    if (username == null || username.isEmpty()) {
        throw new IllegalArgumentException("用戶名不能為空");
    }
    userDao.addUser(username);
}

@Override
public String getUserInfo(int id) {
    if (id <= 0) {
        throw new IllegalArgumentException("用戶ID必須為正數");
    }
    return userDao.getUserById(id);
}

// LoggingAspect.java
@Aspect
@Component
public class LoggingAspect {
// 定義切點：匹配UserService接口的所有方法
@Pointcut(“execution(* com.example.service.UserService.*(…))”)
public void userServicePointcut() {}

// 前置通知
@Before("userServicePointcut()")
public void logBefore(JoinPoint joinPoint) {
    String methodName = joinPoint.getSignature().getName();
    Object[] args = joinPoint.getArgs();
    System.out.println("[前置日志] 調用方法: " + methodName + ", 參數: " + Arrays.toString(args));
}

// 返回通知
@AfterReturning(pointcut = "userServicePointcut()", returning = "result")
public void logAfterReturning(JoinPoint joinPoint, Object result) {
    String methodName = joinPoint.getSignature().getName();
    System.out.println("[返回日志] 方法" + methodName + "返回: " + result);
}

// 異常通知
@AfterThrowing(pointcut = "userServicePointcut()", throwing = "ex")
public void logAfterThrowing(JoinPoint joinPoint, Exception ex) {
    String methodName = joinPoint.getSignature().getName();
    System.out.println("[異常日志] 方法" + methodName + "拋出異常: " + ex.getMessage());
}

// 環(huán)繞通知
@Around("userServicePointcut()")
public Object logAround(ProceedingJoinPoint joinPoint) throws Throwable {
    String methodName = joinPoint.getSignature().getName();
    long startTime = System.currentTimeMillis();
    
    Object result = null;
    try {
        result = joinPoint.proceed();
    } finally {
        long endTime = System.currentTimeMillis();
        System.out.println("[性能日志] 方法" + methodName + "執(zhí)行時間: " + 
                          (endTime - startTime) + "ms");
    }
    return result;
}

// AppConfig.java
@Configuration
@ComponentScan(“com.example”)
@EnableAspectJAutoProxy
public class AppConfig {
}

// Main.java
public class Main {
public static void main(String[] args) {
// 創(chuàng)建IOC容器
ApplicationContext context = new AnnotationConfigApplicationContext(AppConfig.class);

    // 從容器中獲取UserService
    UserService userService = context.getBean(UserService.class);
    
    // 測試正常調用
    userService.registerUser("張三");
    String userInfo = userService.getUserInfo(1);
    System.out.println("獲取到的用戶信息: " + userInfo);
    
    // 測試異常情況
    try {
        userService.registerUser("");
    } catch (IllegalArgumentException e) {
        // 異常已被切面捕獲并記錄
    }
}