07点睛Spring4.1-BeanPostProcessor
2024-08-26 12:42:04
7.1 BeanPostProcessor
- spring通过BeanPostProcessor接口可以对所有bean或者指定的某些bean的初始化前后对bean的检查或者修改提供支持;
- 使用postProcessBeforeInitialization和postProcessAfterInitialization对bean进行操作;
- postProcessBeforeInitialization和postProcessAfterInitialization返回值是bean;
7.2 示例
7.2.1 处理全部bean
7.2.1.1 新建两个测试用的bean
package com.wisely.beanpostprocessor; import org.springframework.stereotype.Service; @Service
public class DemoNormal1Service { }
package com.wisely.beanpostprocessor; import org.springframework.stereotype.Service; @Service
public class DemoNormal2Service { }
7.2.1.2 编写处理所有bean的BeanPostProcessor
package com.wisely.beanpostprocessor; import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.stereotype.Component; @Component
public class DemoAllBeanPostProcessor implements BeanPostProcessor{ public Object postProcessBeforeInitialization(Object bean, String beanName)
throws BeansException {
System.out.println("在 DemoAllBeanPostProcessor的"
+postProcessBeforeInitialization方法里处理bean: " + beanName
+" bean的类型为:"+bean.getClass());
return bean;
} public Object postProcessAfterInitialization(Object bean, String beanName)
throws BeansException {
System.out.println("在 DemoAllBeanPostProcessor的"+
postProcessAfterInitialization方法里处理bean: " + beanName
+" bean的类型为:"+bean.getClass());
return bean;
} }
7.2.1.3 测试
package com.wisely.beanpostprocessor;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class Main {
public static void main(String[] args) {
AnnotationConfigApplicationContext context =
new AnnotationConfigApplicationContext("com.wisely.beanpostprocessor");
context.close();
}
}
输出结果为:
在 DemoAllBeanPostProcessor的postProcessBeforeInitialization方法里处理bean:
demoNormal1Service bean的类型为:class com.wisely.beanpostprocessor.DemoNormal1Service
在 DemoAllBeanPostProcessor的postProcessAfterInitialization方法里处理bean:
demoNormal1Service bean的类型为:class com.wisely.beanpostprocessor.DemoNormal1Service
在 DemoAllBeanPostProcessor的postProcessBeforeInitialization方法里处理bean:
demoNormal2Service bean的类型为:class com.wisely.beanpostprocessor.DemoNormal2Service
在 DemoAllBeanPostProcessor的postProcessAfterInitialization方法里处理bean:
demoNormal2Service bean的类型为:class com.wisely.beanpostprocessor.DemoNormal2Service
7.2.2 处理指定的bean
7.2.2.2 新建指定处理的bean
已经给os和num属性赋值,将在BeanPostProcessor的实现类对类的属性进行修改
package com.wisely.beanpostprocessor; import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service; @Service
public class DemoSelectedService {
@Value("#{systemProperties['os.name']}")
private String os;
@Value("123")
private Long num; public String getOs() {
return os;
} public void setOs(String os) {
this.os = os;
} public Long getNum() {
return num;
} public void setNum(Long num) {
this.num = num;
} }
7.2.2.3 编写指定bean的BeanPostProcessor
packagecom.wisely.beanpostprocessor; importorg.springframework.beans.BeansException;
importorg.springframework.beans.factory.config.BeanPostProcessor;
importorg.springframework.stereotype.Component;
@Component public class DemoSelectedBeanPostProcessor implements BeanPostProcessor { public Object postProcessBeforeInitialization(Objectbean, StringbeanName)
throwsBeansException {
if(bean instanceof DemoSelectedService){
((DemoSelectedService) bean).setOs("Linux");
System.out.println("在DemoSelectedBeanPostProcessor的"+"postProcessBeforeInitialization中将os从windows修改成了Linux" );
}
return bean;
} public Object postProcessAfterInitialization(Objectbean, StringbeanName)
throwsBeansException {
if(bean instanceof DemoSelectedService){
((DemoSelectedService) bean).setNum(456);
System.out.println("在DemoSelectedBeanPostProcessor的"+"postProcessBeforeInitialization中将num从123修改成了456" );
}
return bean;
} }
7.2.2.4 测试
package com.wisely.beanpostprocessor;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class Main {
public static void main(String[] args) {
AnnotationConfigApplicationContext context =
new AnnotationConfigApplicationContext("com.wisely.beanpostprocessor");
DemoSelectedService dss = context.getBean(DemoSelectedService.class);
System.out.println("os确实被修改成了"+dss.getOs());
System.out.println("num确实被修改成了"+dss.getNum());
context.close();
}
}
输出结果
在DemoSelectedBeanPostProcessor的postProcessBeforeInitialization中将os从windows修改成了Linux
在DemoSelectedBeanPostProcessor的postProcessBeforeInitialization中将num从123修改成了456
os确实被修改成了Linux
num确实被修改成了123
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