Java动态代理实现AOP编程问题示例-蒲公英云

Java动态代理实现AOP编程问题示例

在Java中，动态代理是面向切面编程(AOP)的重要实现方式。下面是一个简单的AOP编程问题示例：

定义一个目标类（Subject）：

public class Subject {
 private String name;
 public Subject(String name) {
     this.name = name;
 }
 // 真实的业务逻辑
 public void doSomething() {
     System.out.println("Subject doing something: " + name);
 }
}

定义一个切面（Advice）：

public class LoggingAspect implements advising interfaces {
 @Override
 public void before(ProceedingJoinPoint pjp) throws Throwable {
     System.out.println("Logging aspect entering: " + pjp.getSignature());
 }
 @Override
 public void afterThrowing(ThrowingJoinPoint pjp, Throwable t) throws Throwable {
     System.out.println("Logging aspect exiting due to exception: " + pjp.getSignature());
 }
}

配置动态代理（创建代理类）：
```java
import java.lang.reflect.Method;
import java.util.Arrays;

public class Main {

public static void main(String[] args) throws Throwable {
    // 1. 创建目标类Subject
    Subject subject = new Subject("Example Subject");
    // 2. 创建切面LoggingAspect
    LoggingAspect loggingAspect = new LoggingAspect();
    // 3. 配置动态代理（创建代理类））
    // 使用Proxy.newProxyInstance()方法，传入参数：目标对象、实现接口、是否可变
    Class<?> proxyClass = Proxy.getProxyClass(subject.getClass(), loggingAspect.getClass()));
    // 4. 获取并使用代理对象
    Subject proxySubject = (Subject) proxyClass.newInstance();
    proxySubject.doSomething();
    // 5. 通过代理对象访问切面方法
    Method beforeMethod = loggingAspect.getClass().getMethod("before", proxySubject.getClass()));
    beforeMethod.invoke(loggingAspect);
    Method afterThrowingMethod = loggingAspect.getClass().getMethod("afterThrowing", proxySubject.getClass(), Arrays.asList(new Object[]{new Throwable("Test Exception")}}))));
    afterThrowingMethod.invoke(loggingAspect);
}