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接口的动态代理

• 事务
  两种结果：提交 回滚
  提交：发生在return
  回滚：全回滚 / 回滚到定义的保存点
  接口：

public class UserServiceImpl implements UserService { 
   
    public void addUser() { 
   
        System.out.println("addUser");
    }
}

测试类：

 @Test
    public void t3(){ 
   
        final UserServiceImpl userService=new UserServiceImpl();
        /* * ClassLoader loader, 一般调用当前类的类加载器 * Class<?>[] interfaces, * InvocationHandler h * */
        InvocationHandler handler= new InvocationHandler() { 
   
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { 
   
                System.out.println("开启事务");
                Object object=  method.invoke(userService,args);
                System.out.println("关闭事务");
                return object;
            }

        };
        UserService userServiceProxy= (UserService) Proxy.newProxyInstance(Test01.class.getClassLoader(),
                UserServiceImpl.class.getInterfaces(),handler );
        userServiceProxy.addUser();

    }

统一事务处理

统一事务处理类：

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
/* * 重写了 BeanPostProcessor * 配置的方法非常简单，只要配置给容器就可以了 * */
public class MyBeanPostProcess implements BeanPostProcessor{ 
   
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { 
   
        System.out.println("Before-Initialization");
        System.out.println(bean);
        System.out.println(beanName);
        return bean;
    }
    public Object postProcessAfterInitialization(final Object bean, String beanName) throws BeansException { 
   
        System.out.println("After-Initialization");
        if(beanName.equals("userService" )){ 
   
            InvocationHandler handler= new InvocationHandler() { 
   
                public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { 
   
                    System.out.println("开启事务");
                    Object object=  method.invoke(bean,args);
                    System.out.println("关闭事务");
                    return object;
                }
            };
            // BeanPostProcessor全局生效 需要使用名称进行过滤
            return Proxy.newProxyInstance(MyBeanPostProcess.class.getClassLoader(),
                    bean.getClass().getInterfaces(),handler);
        }else { 
   
            return bean;
        }
    }
}

applicationContext.xml配置;

<bean class="com.xbj.dao.impl.UserServiceImpl" id="userService" />
<bean class="com.xbj.dao.MyBeanPostProcess" />
 <!--配置BeanPostProcess 全局生效-->

userService：

public interface UserService { 
   
    void addUser();
}

UserServiceImpl：

public class UserServiceImpl implements UserService { 
   
    public void addUser() { 
   
        System.out.println("addUser");
    }
}

测试类：

    private ClassPathXmlApplicationContext context;
    @Before
    public void t1(){ 
   
        context= new ClassPathXmlApplicationContext("applicationContext.xml");
    }
    @Test
    public void t2(){ 
   
        UserService userService=context.getBean("userService",UserService.class);
        userService.addUser();
        context.close();
    }