公用接口和实现

public interface Calculator {
    public Integer add(Integer num1, Integer num2);
    public Integer minus(Integer num1, Integer num2);
}

public class CalculatorImpl implements Calculator {
 
    @Override
    public Integer add(Integer num1, Integer num2) {
        int ret = num1 + num2;
        System.out.println("in calculatorImpl, res: " + ret);
        return ret;
    }
     
    @Override
    public Integer minus(Integer num1, Integer num2) {
        int ret = num1 - num2;
        System.out.println("int calculatorImpl, res: " + ret);
        return ret;
    }
}

静态代理

public class StaticCalculatorProxy implements Calculator {
    Calculator obj;
     
    public StaticCalculatorProxy(Calculator obj) {
        this.obj = obj; 
    }
 
    @Override
    public Integer add(Integer num1, Integer num2) {
        System.out.println("in StaticCalculatorProxy, before invocation");
        Integer ret = obj.add(num1, num2);
        System.out.println("in StaticCalculatorProxy, after invocation");
        return ret;
    }
 
    @Override
    public Integer minus(Integer num1, Integer num2) {
        System.out.println("in StaticCalculatorProxy, before invocation");
        Integer ret = obj.minus(num1, num2);
        System.out.println("in StaticCalculatorProxy, after invocation");
        return ret;
    }
 
}

测试代码：

public static void staticProxy() {
        CalculatorImpl calculator = new CalculatorImpl();
        StaticCalculatorProxy calculatorProxy = new StaticCalculatorProxy(calculator);
        calculatorProxy.add(1, 2);
        calculatorProxy.minus(2, 1);
    }

动态代理

public class CalculatorHandler implements InvocationHandler {
     
    private Object obj; //被代理类
    public CalculatorHandler(Object obj) {
        this.obj = obj;
    }
 
    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        System.out.println("in calculatorhandler, before invocation");
        Object ret = method.invoke(obj, args);  //执行被代理类方法
        System.out.println("in calculationhandler, after invocation");
        return ret;
    }
}

测试代码：

public static void dynamicProxy() {
        CalculatorImpl calculatorImpl = new CalculatorImpl();//被代理类
        CalculatorHandler calculatorHandler = new CalculatorHandler(calculatorImpl);
        Calculator calculator = (Calculator) Proxy.newProxyInstance(
                calculatorImpl.getClass().getClassLoader(),
                calculatorImpl.getClass().getInterfaces(), calculatorHandler);
        calculator.add(1, 2);
        calculator.minus(1, 2);
    }