Java Spring注释：为什么@Required不'；当类为@Autowired时无法工作

当我有一节课时，如下所示：

public class MyConfig {
    private Integer threshold;

    @Required
    public void setThreshold(Integer threshold) { this.threshold = threshold; }
}

public class Trainer {
    @Autowired
    private MyConfig configuration;

    public void setConfiguration(MyConfig configuration) { this.configuration = configuration; }
}

<bean id="myConfiguration" class="com.xxx.config.MyConfig">
        <!--<property name="threshold" value="33"/>-->
</bean>

我的用法如下：

public class MyConfig {
    private Integer threshold;

    @Required
    public void setThreshold(Integer threshold) { this.threshold = threshold; }
}

public class Trainer {
    @Autowired
    private MyConfig configuration;

    public void setConfiguration(MyConfig configuration) { this.configuration = configuration; }
}

<bean id="myConfiguration" class="com.xxx.config.MyConfig">
        <!--<property name="threshold" value="33"/>-->
</bean>

并在xml上下文中初始化培训师，如下所示：

public class MyConfig {
    private Integer threshold;

    @Required
    public void setThreshold(Integer threshold) { this.threshold = threshold; }
}

public class Trainer {
    @Autowired
    private MyConfig configuration;

    public void setConfiguration(MyConfig configuration) { this.configuration = configuration; }
}

<bean id="myConfiguration" class="com.xxx.config.MyConfig">
        <!--<property name="threshold" value="33"/>-->
</bean>

出于某种原因，@Required注释不适用，上下文启动时没有问题（它应该抛出一个异常，说明字段阈值是必需的…）

---

为什么会这样？？？

我想你可能错过了一个配置

仅应用@Required注释不会强制该属性 检查时，您还需要注册 Required注释BeanPostProcessor了解@Required bean配置文件中的注释

<beans 
...
xmlns:context="http://www.springframework.org/schema/context"
...
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-2.5.xsd" >
...
<context:annotation-config />
...
</beans>

可以通过两种方式启用所需的AnnotationBeanPostProcessor。

包括

在bean配置文件中添加Spring上下文和

<beans 
...
xmlns:context="http://www.springframework.org/schema/context"
...
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-2.5.xsd" >
...
<context:annotation-config />
...
</beans>

---

检查您是否配置了所需的注释BeanPostProcessor。否则，

@Required

将不会被扫描。我不明白为什么我只在使用@Autowired时才需要这个bean，但它可以工作！谢谢