1. InitializingBean
- 这个接口 InitailizingBean中只有一个方法,就是afterPropertiesSet。该方法是指Spring容器在启动后主动调用该接口的方法。
- 如果一个Bean实现了InitializingBean,则该方法会在容器实例化该Bean,初始化Bean的属性完毕之后,再调用afterPropertiesSet方法。
- afterPropertiesSet通过方法名称即可知道含义:在bean的属性设置完毕后调用该方法。
接口InitializingBean接口源码如下:
public interface InitializingBean {
/**
* 当Bean的属性被设置完毕后,由BeanFactory调用该方法。
* 该方法允许bean的实例去执行一些初始化动作,当所有的bean属性完成设置之后执行。
*/
void afterPropertiesSet() throws Exception;
}
2. ApplicationContextWare
- 名称带Aware,就可以知道这个接口由Spring容器主动通知调用。Spring容器在通知该接口的实现类时,会将上下文ApplicationContext注入进来。
- 接口中就一个方法:
void setApplicationContext(ApplicationContext applicationContext) throws BeansException - 即容器启动后,将ApplicationContext 注入到该方法中。
接口ApplicationContextWare源码如下:
public interface ApplicationContextAware extends Aware {
void setApplicationContext(ApplicationContext var1) throws BeansException;
}
3. 例子
- 3.1 枚举类FamilyEnum
package com.example.demo.blogTest;
public enum FamilyEnum {
FATHER(45, "father"),
MOTHER(42, "mother"),
SON(18, "son");
private Integer age;
private String name;
FamilyEnum(Integer age, String name) {
this.age = age;
this.name = name;
}
public Integer getAge() {
return age;
}
public String getName() {
return name;
}
}
- 3.2 自定义注入类FamilyHolder
package com.example.demo.blogTest;
import com.example.demo.service.BaseService;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;
import java.util.HashMap;
import java.util.Map;
import java.util.function.Function;
import java.util.stream.Collectors;
@Component
public class FamilyHolder implements InitializingBean, ApplicationContextAware {
private ApplicationContext applicationContext;
private Map<FamilyEnum, BaseService> map = new HashMap<>();
public BaseService getEnum(FamilyEnum familyEnum) {
return map.get(familyEnum);
}
@Override
public void afterPropertiesSet() throws Exception {
map = applicationContext.getBeansOfType(BaseService.class)
.values()
.stream()
.collect(Collectors.toMap(BaseService::getEnum, Function.identity()));
}
@Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
this.applicationContext = applicationContext;
}
}
- 3.3 抽象类BaseService
package com.example.demo.service;
import com.example.demo.blogTest.FamilyEnum;
public abstract class BaseService {
// 抽象工作类,具体实现由其继承者实现
public abstract void myJob();
public abstract FamilyEnum getEnum();
// 通用方法,也可以被继承者重写
public String getName(FamilyEnum person) {
return person.getName();
}
}
- 3.4 抽象继承类FatherService
package com.example.demo.service;
import com.example.demo.blogTest.FamilyEnum;
import org.springframework.stereotype.Service;
@Service
public class FatherService extends BaseService{
@Override
public void myJob() {
System.out.println("I am a engineer!");
}
@Override
public FamilyEnum getEnum() {
return FamilyEnum.FATHER;
}
}
- 3.5 抽象继承类MotherService
package com.example.demo.service;
import com.example.demo.blogTest.FamilyEnum;
import org.springframework.stereotype.Service;
@Service
public class MotherService extends BaseService{
@Override
public void myJob() {
System.out.println("I am a teacher!");
}
@Override
public FamilyEnum getEnum() {
return FamilyEnum.MOTHER;
}
}
- 3.6 抽象继承类MyService
package com.example.demo.service;
import com.example.demo.blogTest.FamilyEnum;
import org.springframework.stereotype.Service;
@Service
public class MyService extends BaseService{
@Override
public void myJob() {
System.out.println("I am a student!");
}
@Override
public FamilyEnum getEnum() {
return FamilyEnum.SON;
}
}
- 3.7 测试类DemoApplicationTests
package com.example.demo;
import com.example.demo.blogTest.FamilyEnum;
import com.example.demo.blogTest.FamilyHolder;
import com.example.demo.service.BaseService;
import org.junit.jupiter.api.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
@RunWith(SpringRunner.class)
@SpringBootTest
class DemoApplicationTests {
@Autowired
private FamilyHolder familyHolder;
@Test
void contextLoads() throws ClassNotFoundException {
// 通过反射获取所有枚举元素
Class<FamilyEnum> clazz = (Class<FamilyEnum>) Class.forName("com.example.demo.blogTest.FamilyEnum");
FamilyEnum[] enumConstants = clazz.getEnumConstants();
for (FamilyEnum familyEnum : enumConstants) {
BaseService baseService = familyHolder.getEnum(familyEnum);
baseService.myJob();
}
}
}
- 输出结果
I am a engineer!
I am a teacher!
I am a student!
4. 参考文献
- https://blog.youkuaiyun.com/douunderstand/article/details/78835515
- https://blog.youkuaiyun.com/junchenbb0430/article/details/78606380?utm_medium=distribute.pc_relevant.none-task-blog-baidujs_title-3&spm=1001.2101.3001.4242