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1：问题描述

配置文件application.yml：

person.name: nobodyperson.age: 20

实体类Person：

package com.nobody.pojo.entity;import java.io.Serializable;import org.springframework.beans.factory.annotation.Value;import org.springframework.stereotype.Component;@Componentpublic class Person implements Serializable {
           /**     *      */    private static final long serialVersionUID = -8245392957106320519L;    @Value("${person.name}")    private static String name;        private static String age;        @Value("${person.age}")    public void setAge(String age) {
           Person.age = age;    }        public void setName(String name) {
           Person.name = name;    }        public static String getName() {
           return name;    }        public static String getAge() {
           return age;    }}

测试接口类DemoController：

package com.nobody.controller;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;import com.nobody.ehr.pojo.entity.Person;@RequestMapping("demo")@RestControllerpublic class DemoController {
           @GetMapping    public String demo() {
                   System.out.println("name:" + Person.getName() + ", age:" + Person.getAge());                return "";    }}

测试结果：

name:null, age:20

2：分析

启动日志：

[19:37:45] INFO  [restartedMain] o.s.b.f.a.AutowiredAnnotationBeanPostProcessor 			    - Autowired annotation is not supported on static fields: private static java.lang.String com.nobody.pojo.entity.Person.name

源码分析：

private InjectionMetadata buildAutowiringMetadata(final Class
    clazz) {
   		List
   
     elements = new ArrayList<>();		Class
     targetClass = clazz;		do {
   			final List
    
      currElements = new ArrayList<>();			ReflectionUtils.doWithLocalFields(targetClass, field -> {
   				AnnotationAttributes ann = findAutowiredAnnotation(field);				if (ann != null) {
             //这里对静态属性注入做了过滤					if (Modifier.isStatic(field.getModifiers())) {
   						if (logger.isInfoEnabled()) {
   							logger.info("Autowired annotation is not supported on static fields: " + field);						}						return;					}					boolean required = determineRequiredStatus(ann);					currElements.add(new AutowiredFieldElement(field, required));				}			});			ReflectionUtils.doWithLocalMethods(targetClass, method -> {
   				Method bridgedMethod = BridgeMethodResolver.findBridgedMethod(method);				if (!BridgeMethodResolver.isVisibilityBridgeMethodPair(method, bridgedMethod)) {
   					return;				}				AnnotationAttributes ann = findAutowiredAnnotation(bridgedMethod);				if (ann != null && method.equals(ClassUtils.getMostSpecificMethod(method, clazz))) {
             //这里对静态方法做了过滤					if (Modifier.isStatic(method.getModifiers())) {
   						if (logger.isInfoEnabled()) {
   							logger.info("Autowired annotation is not supported on static methods: " + method);						}						return;					}					if (method.getParameterCount() == 0) {
   						if (logger.isInfoEnabled()) {
   							logger.info("Autowired annotation should only be used on methods with parameters: " +									method);						}					}					boolean required = determineRequiredStatus(ann);					PropertyDescriptor pd = BeanUtils.findPropertyForMethod(bridgedMethod, clazz);					currElements.add(new AutowiredMethodElement(method, required, pd));				}			});			elements.addAll(0, currElements);			targetClass = targetClass.getSuperclass();		}		while (targetClass != null && targetClass != Object.class);		return new InjectionMetadata(clazz, elements);	}
    
   

3：结论

从源码上发现，理论上spring是可以对静态域注入的，只是spring没有这样做，它认为依赖注入发生的时段是在实例的生命周期，而不是类的生命周期。

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