Spring-Aop和自定义注解的简单应用

2018-09-20

字数统计: 583字 | 阅读时长: 3分

简介

AOP称为面向切面编程，在程序开发中主要用来解决一些系统层面上的问题，比如日志，事务，权限等，本文记录了使用spring-aop和自定义注解实现事务处理的例子。

1.自定义注解

@Target({ ElementType.METHOD })
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface TxManagerAnnotation {

    String db() default "";

    int level() default Connection.TRANSACTION_REPEATABLE_READ;

}

2.应用自定义注解的Service

public interface UserService {

    User getUser(Integer id);

    void setUser(User user);

    void delUser(Integer id);
}

@Service
public class UserServiceImpl implements UserService {

    @Override
    public User getUser(Integer id) {

        System.out.println("useService: getUser: " + id);
        return new User(id, 'xxx');
    }

    @Override
    @TxManagerAnnotation 	//<font color=#ca0c16>应用注解,实现事务处理</font>
    public void setUser(@CheckEmpty(fields = "id") User user) {

        System.out.println("useService: setUser: " + user.toString());
    }

    @Override
    @TxManagerAnnotation   //<font color=#ca0c16>应用注解,实现事务处理</font>
    public void delUser(Integer id) {

        System.out.println("useService: delUser: " + id);
    }
}

3.事务处理类

public class TxManagerUtil {

    private String db;

    private Integer level;

    public TxManagerUtil(String db, Integer level) {
        this.db = db;
        this.level = level;
    }

    public void begin() {
        System.out.println("开启事务");
    }

    public void commit() {
        System.out.println("提交事务");
    }

    public void rollback() {
        System.out.println("回滚事务");
    }

    public void close() {
        System.out.println("关闭事务");
    }
}

4.切点处理

@Component
public class TxManagerInterceptor implements MethodInterceptor {

    @Override
    public Object invoke(MethodInvocation methodInvocation) throws Throwable {

        TxManagerAnnotation txManagerAnnotation = methodInvocation.getMethod().getAnnotation(TxManagerAnnotation.class);
        String db = txManagerAnnotation.db();
        Integer level = txManagerAnnotation.level();
        TxManagerUtil txManagerUtil = new TxManagerUtil(db, level);

        Object result = null;
        try {
            txManagerUtil.begin();
            result = methodInvocation.proceed();
            txManagerUtil.commit();
        } catch (Exception e) {
            txManagerUtil.rollback();
        } finally {
            txManagerUtil.close();
        }
        return result;
    }
}

5.配置spring-aop

<context:component-scan base-package="com.sujiawei.java" />
<!--<font color=#ca0c16>切点处理</font>-->
<bean id="txManagerInterceptor" class="com.sujiawei.java.aop.TxManagerInterceptor"/> 

<aop:config proxy-target-class="true">
<!--<font color=#ca0c16>切点作用域</font>-->
<aop:pointcut id="checkPointcut" expression="execution(* com.sujiawei.java..*.*(..)) and @annotation(com.sujiawei.java.annotation.TxManagerAnnotation)" />
<!--<font color=#ca0c16>切点具体处理</font>-->
<aop:advisor advice-ref="txManagerInterceptor" pointcut-ref="checkPointcut" />
</aop:config>

例子中使用了接口，所以proxy-target-class=”true” 该设置会使用cglib代理，spring会获取到实现类上的注解

5.测试类

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:aop/spring-aop-test.xml")
public class CheckEmptyAnnoTest {

        @Resource
        private UserService userService;

        @Test
        public void testCheckEmptyAnno() {
            User user = new User();
            user.setId(1111);
            user.setName("jsw");
            userService.setUser(user);
        }
}

6.运行结果

开启事务
useService: setUser: com.sujiawei.java.bean.User@7e990ed7
提交事务
关闭事务