Spring MVC 中的依赖注入抛出 NullPointerException

Question

这是我的问题：我正在使用 SpringMVC，并且在调用 @Autowired 依赖项时出现 NullPointerException 。

这是@Service：

package x.y.z.service

@Repository("myService")
public class MyServiceImpl implements MyService {
   /* ... */
}

该服务在应用程序中的任何地方都会自动装配，没有任何问题，除了这里：

package x.y.z.utils

@Component
public class TestClass {

    @Autowired
    private MyService myService;

    public TestClass() {
    super();
    }

    public void tester() {
    myService.find(1);
    }
}

方法 tester() 在 myService 上抛出 NP 异常。当跟踪日志时，我发现该 bean 由 Spring 管理。

应用程序上下文文件非常简单：

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/mvc"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:beans="http://www.springframework.org/schema/beans"
    xsi:schemaLocation="
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">

    <annotation-driven />   

    <interceptors>
        <!-- ... -->
    </interceptors>

    <resources mapping="/resources/**" location="/resources/" />

    <!-- Resolves views selected for rendering by @Controllers to .jsp resources in the /WEB-INF/views directory -->
    <beans:bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <beans:property name="prefix" value="/WEB-INF/views/" />
        <beans:property name="suffix" value=".jsp" />
    </beans:bean>

    <!-- Imports user-defined @Controller beans that process client requests -->
    <beans:import resource="controllers.xml" />

    <beans:bean id="validator" class="org.springframework.validation.beanvalidation.LocalValidatorFactoryBean" />

</beans:beans>

和引用的controllers.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd  
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">

    <!-- Scans within the base package of the application for @Components to 
        configure as beans -->
    <context:component-scan base-package="x.y.z" />
    <context:annotation-config />

</beans>

经过两天的搜索，我找不到任何帮助。我错过了什么吗？

谢谢

Answer 1

请确保您有

<context:component-scan base-package="x.y.z"/>

此外，请添加：

 <context:annotation-config/> 

更新：

很抱歉，您的 xml 在架构方面不正确，并且缺少我告诉您添加的内容：

这就是您的文件的方式应该看起来像：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xmlns:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">
<context:annotation-config />
<context:component-scan base-package="x.y.z"></context:component-scan>
</beans>