Spring基于接口的动态代理和统一事务处理

红太狼 2022-01-14 06:53 299阅读 0赞

# 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  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NjUxMjY3_size_16_color_FFFFFF_t_70]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;

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();
        }

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NjUxMjY3_size_16_color_FFFFFF_t_70]: /images/20220114/1512a936b2d248b384f1fbf118ad89fc.png