Java静态代理和动态代理详解

public interface ILogin {
    void doLogin();
}

public class UserLogin implements ILogin {
  @Override
  public void doLogin(){
      System.out.print("用户登录逻辑");
  }   
}

public class UserLoginProxy implements ILogin {
  private UserLogin mUserLogin;
  public UserLoginProxy() {
    mUserLogin = new UserLogin();
  }
  @Override
  public void doLogin(){
    //...
    System.out.print("登录前逻辑");
    //真正的业务逻辑还是由目标类来实现
    mUserLogin.doLogin();
    System.out.print("登录后逻辑");     
    //...
  }
}

	public static void main(String[] args){
     //
     ILogin iLogin = new UserLoginProxy();
     iLogin.doLogin();
	}

private InvocationHandler mInvocationHandler = new InvocationHandler() {
        @Override
        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
            //target 是目标类对象
            Object result = method.invoke(target,args);
            //
            return result;
        }
    };
//方式1
//创建代理类的 Class 对象，参数 (ClassLoader 类加载器,Class<?>)
Class<?> proxyClass = Proxy.getProxyClass(Toast.class.getClassLoader(), Toast.class);
//通过反射实例化代理对象
Toast toastProxy = (Toast) proxyClass.getConstructor(InvocationHandler.class).newInstance(mInvocationHandler);
//方式2，是方法1的简化版，newProxyInstance 内部代码逻辑和方法1基本一致
//直接创建代理对象，参数 (ClassLoader 类加载器,Class<?>[],InvocationHandler)
Toast toastProxy2 = (Toast) Proxy.newProxyInstance(Toast.class.getClassLoader(),new Class<?>[]{Toast.class}, mInvocationHandler);

public interface ICalculator {
    int add(int a, int b);
    int minus(int a, int b);
}

public class Calculator implements ICalculator {
    @Override
    public int add(int a, int b) {
        return a + b;
    }
    @Override
    public int minus(int a, int b) {
        return a - b;
    }
}

  public class CalculatorInvocationHandler implements InvocationHandler {
      private Object target;
      public CalculatorInvocationHandler(Object target) {
          this.target = target;
      }
      @Override
      public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
          // 在方法调用前可以添加一些逻辑
          Object result = method.invoke(target, args);
          // 在方法调用后也可以添加一些逻辑
          return result;
      }
  }

//目标类
ICalculator calculator = new Calculator();
//代理类
ICalculator proxyCalculator = (ICalculator) Proxy.newProxyInstance(
        calculator.getClass().getClassLoader(),
        calculator.getClass().getInterfaces(),
        new CalculatorInvocationHandler(calculator)
);