浅析Java中的动态代理

public interface Buyer {
    
    String buy();
}

public class BuyerImpl implements Buyer{
    public String buy() {
        System.out.println("本人卖房，从不坑人...");
        return "一次搞定";
    }
}

public class BuyerInvocationHandler implements InvocationHandler {
    //被代理对象
    private Object target;

    
    public void setTarget(Object target) {
        this.target = target;
    }

    
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        System.out.println("熬夜满大街收集电话号码.....");
        //调用核心业务方法
        Object result = method.invoke(target,args);

        System.out.println("不满意，再找我...");

        return result;
    }
}

public class BuyerProxyFactory {
    
    public static <T> T create(Object target){
        // 创建动态代理对象
        BuyerInvocationHandler handler = new BuyerInvocationHandler();
        // 设置被代理对象
        handler.setTarget(target);
        // 动态创建执行业务方法的代理对象
        return  (T) Proxy.newProxyInstance(
                target.getClass().getClassLoader(),
                target.getClass().getInterfaces(),
                handler);
    }
}

public class example {
    public static void main(String[] args) {
        //定义被代理对象
        //定义被代理对象
        Buyer buyer = new BuyerImpl();
        buyer.buy();  // 直接调用业务方法，没有代理的功能
        // 使用代理工厂创建动态代理类对象
        Buyer proxyBuyer = BuyerProxyFactory.create(buyer);
        proxyBuyer.buy();
    }
}

<dependency>
    <groupId>cglib</groupId>
    <artifactId>cglib-nodep</artifactId>
    <version>3.3.0</version>
</dependency>

public class OrderService {
    public int insert(){
        System.out.println("添加订单....");
        return 0;
    }
}

public class TransactionProxyFactory {
    
    public static <T> T create(Class<T> clazz){
        Enhancer enhancer = new Enhancer();
        // 采用接口内部类的方式实现代理功能
        enhancer.setCallback(new MethodInterceptor() {
            public Object intercept(Object target, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
                System.out.println("开始事务。。。。");
                // 核心业务,调用父类的方法
                Object result = methodProxy.invokeSuper(target,objects);
                System.out.println("提交或回滚事务....");
                return result;
            }
        });
        // 设置代理类的父类
        enhancer.setSuperclass(clazz);
        // 返回创建的动态代理类对象
        return (T) enhancer.create();
    }
}

public class TransactionProxyFactoryTest {
    public static void main(String[] args) {
        // 使用代理创建业务逻辑类
        OrderService orderService =
                TransactionProxyFactory.create(OrderService.class);
        orderService.insert();

        CartService cartService = TransactionProxyFactory.create(CartService.class);
        cartService.insert();
    }
}