静态代理和动态代理代码实现

一、静态代理

public class UserServiceImpl implements UserService {
    @Override
    public void add() {

    }
}






public class UserProxy {
    private UserService userService;

    public UserProxy(UserService userService) {
        this.userService = userService;
    }

    public void add(){
        System.out.println("开启静态代理事务");
        System.out.println("更新user");
        System.out.println("提交静态代理事务");
    }
}

2.测试代码

@SpringBootTest
class StaticproxyApplicationTests {

    @Test
    void contextLoads() {
        UserService userService = new UserServiceImpl();
        UserProxy userProxy = new UserProxy(userService);
        userProxy.add();
    }



}

二、动态代理

public class DynamicProxy implements InvocationHandler {
    private Object target;

    public DynamicProxy(Object target) {
        this.target = target;
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        System.out.println("动态代理开启事务");
        Object invoke = method.invoke(target, args);
        System.out.println("动态代理提交事务");
        return invoke;
    }

    public static void main(String[] args) {
        UserService userService = new UserServiceImpl();
        DynamicProxy dynamicProxy = new DynamicProxy(userService);
        ClassLoader classLoader = userService.getClass().getClassLoader();
        Class[] interfaces = userService.getClass().getInterfaces();
        UserService service = (UserService) Proxy.newProxyInstance(classLoader, interfaces, dynamicProxy);
        service.add();
    }
}

总结：

静态代理编译期生成代理类；动态代理运行期生成代理类。

静态代理和被代理类及其业务逻辑耦合,适用性较差且代理逻辑难以扩展;动态代理可以在不知道被代理类的前提下编写代理逻辑，运行时才决定被代理对象，适用性好且代理逻辑易于扩展。