Java 实现拦截器Interceptor的拦截功能方式

public interface BusinessFacade {
    public void doSomething();
}

public class BusinessClass implements BusinessFacade {
    public void doSomething() {
        System.out.println("在业务组件 BusinessClass 中调用方法: doSomething()");
    }
}

public class InterceptorClass {
    // 在 action 之前调用
    public void before(){
        System.out.println("在拦截器 InterceptorClass 中调用方法: before()");
    }
    // 在 action 之后调用
    public void after(){
        System.out.println("在拦截器 InterceptorClass 中调用方法: after()");
    }
}

public class DynamicProxyHandler implements InvocationHandler {
    // 声明被代理对象
    private Object business;
    // 创建拦截器
    private InterceptorClass interceptor = new InterceptorClass();
    
    public Object bind(Object business) {
        this.business = business;
        
        return Proxy.newProxyInstance(business.getClass().getClassLoader(),
                business.getClass().getInterfaces(),
                this);
    }
    
   public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
       Object result = null;
       interceptor.before();
       result = method.invoke(business, args);
       interceptor.after();
       return null;
   }
}

public class ClientDemo {
    public static void main(String args[]) {
        // 创建动态代理处理工具
        DynamicProxyHandler handler = new DynamicProxyHandler();
        // 创建业务组件对象
        BusinessFacade business = new BusinessClass();
        // 创建业务组件对象，并用动态代理绑定代理类
        BusinessFacade businessProxy = (BusinessFacade) handler.bind(business);
        // 调用业务组件中的方法，演示拦截器效果
        businessProxy.doSomething();
    }
}