求教 Dubbo 的使用注解 annotation 报 null 指针问题 - V2EX
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xiaofdejimo
V2EX    Java

求教 Dubbo 的使用注解 annotation 报 null 指针问题

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  •   xiaofdejimo Nov 5, 2017 9131 views
    This topic created in 3095 days ago, the information mentioned may be changed or developed.

    在学 dubbo,想用注解,然后消费方一直报空指针,我先声明没加入 SpringMVC 或者 boot 导致加载顺序出错,我就是纯 spring 下写 demo 学习,贴一下我的配置和代码,求大佬指点问题所在

    提供方 xml

    <!-- 加入 spring 注解扫描 --> <context:component-scan base-package="com.hanting"/> <!--计算依赖关系--> <dubbo:application name="provider"/> <!--使用 zookeeper 注册中心暴露服务--> <dubbo:registry address="zookeeper://localhost:2181"/> <!-- 用 dubbo 协议在 20880 端口暴露服务 --> <dubbo:protocol name="dubbo" port="20880"/> <!-- 使用注解方式暴露接口 --> <dubbo:annotation package="com.hanting"/> <!-- 接口--> <dubbo:service interface="com.hanting.service.UserService" ref="userService" /> 

    提供方 impl

    import com.alibaba.dubbo.config.annotation.Service; import com.hanting.service.UserService; import org.springframework.stereotype.Component; @Component("userService") @Service() public class UserServiceImpl implements UserService { ... } 

    消费方 xml

    <dubbo:application name="consumer"/> <!--向 zookeeper 订阅 provider 的地址,由 zookeeper 定时推送--> <dubbo:registry address="zookeeper://localhost:2181"/> <!--使用 dubbo 协议调用定义好的 api.PermissionService 接口--> <dubbo:reference id="userService" interface="com.hanting.service.UserService"/> <!-- 使用注解方式暴露接口 --> <dubbo:annotation package="com.hanting"/> <!-- 加入 spring 注解扫描 --> <context:component-scan base-package="com.hanting"/> 

    消费方测试

    import com.alibaba.dubbo.config.annotation.Reference; import com.hanting.service.UserService; import org.springframework.stereotype.Component; @Component public class UserTest { @Reference private UserService userService; public void test() { userService.addUser("aaa"); } } 

    消费方的 console

    consumer start... Exception in thread "main" java.lang.NullPointerException at com.hanting.controller.UserTest.test(UserTest.java:25) at Consumer.main(Consumer.java:19) 
    4 replies    2017-11-06 16:50:44 +08:00
    yidinghe
        1
    yidinghe  
       Nov 5, 2017
    private UserService userService;

    因你的代码没有正确指明 25 行在哪里,所以我猜是这个成员并没有被赋值。为什么不用 @Autowired
    bxb100
        2
    bxb100  
       Nov 5, 2017
    没用过 Dubbo, 难道 Spring DI 注入不是提供实现类吗
    lishunli
        3
    lishunli  
       Nov 6, 2017
    提供方删除
    <context:component-scan base-package="com.hanting"/>
    <dubbo:service interface="com.hanting.service.UserService" ref="userService" />

    消费方删除
    <dubbo:reference id="userService" interface="com.hanting.service.UserService"/>
    <context:component-scan base-package="com.hanting"/>

    dubbo:annotation 就已经包含了上面的,再试试
    xiaofdejimo
        4
    xiaofdejimo  
    OP
       Nov 6, 2017
    @lishunli 这个后来我也反应过来了,我的问题我想明白了,是我调用这个消费者的时候是直接 new 出来调用的,不是通过 springIOC 给我的,所以就无法扫描到注解,是我 spring 这儿没想明白
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