| 知乎专栏 |
目录
Spring框架为基于Java的现代企业级应用程序提供了全面的编程和配置模型——适用于任何类型的部署平台。
Spring框架的关键要素是应用程序级别的基础设施支持：Spring专注于企业级应用程序的“管道”，以便团队可以专注于应用程序级别的业务逻辑，而无需与特定的部署环境产生不必要的联系。
package cn.netkiller.config;
import lombok.Data;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component;
@Configuration
@Data
public class Config {
@Bean
public MyBean myBean() {
return new MyBean();
}
@Bean(initMethod = "init", destroyMethod = "destroy")
public MyBean myBean2() {
return new MyBean();
}
@Bean({"myBean4", "myBean5"})
@Scope("prototype")
public MyBean myBean3() {
return new MyBean();
}
public class MyBean {
public MyBean() {
System.out.println("MyBean Initializing");
}
public String output() {
return "Helloworld!!!";
}
public void init() {
System.out.println("Bean 初始化方法被调用");
}
public void destroy() {
System.out.println("Bean 销毁方法被调用");
}
}
}
查看注入情况
neo@MacBook-Pro-M2 ~/w/watch (main)> curl -s 'http://neo:chen@localhost:8080/actuator/beans' |jq | grep -i mybean -A 5
"myBean2": {
"aliases": [],
"scope": "singleton",
"type": "cn.netkiller.config.Config$MyBean",
"resource": "class path resource [cn/netkiller/config/Config.class]",
"dependencies": [
"config"
]
},
--
"myBean4": {
"aliases": [
"myBean5"
],
"scope": "prototype",
"type": "cn.netkiller.config.Config$MyBean",
"resource": "class path resource [cn/netkiller/config/Config.class]",
"dependencies": []
},
"dbHealthContributor": {
"aliases": [],
--
"myBean": {
"aliases": [],
"scope": "singleton",
"type": "cn.netkiller.config.Config$MyBean",
"resource": "class path resource [cn/netkiller/config/Config.class]",
"dependencies": [
"config"
]
},
@Bean({"neo","netkiller"})
@Scope("prototype")
public MyBean myBean(){
return new MyBean();
}
Scope 详解 singleton 默认单例的bean定义信息，对于每个IOC容器来说都是单例对象 prototype bean对象的定义为任意数量的对象实例 request bean对象的定义为一次HTTP请求的生命周期，也就是说，每个HTTP请求都有自己的bean实例，它是在单个bean定义的后面创建的。仅仅在web-aware的上下文中有效 session bean对象的定义为一次HTTP会话的生命周期。仅仅在web-aware的上下文中有效 application bean对象的定义范围在ServletContext生命周期内。仅仅在web-aware的上下文中有效 websocket bean对象的定义为WebSocket的生命周期内。仅仅在web-aware的上下文中有效
singleton和prototype 一般都用在普通的Java项目中，而request、session、application、websocket都用于web应用中。
@Bean
@Scope(value = "singleton")
public Person person(){
return new Person();
}
ConfigurableBeanFactory.SCOPE_PROTOTYPE，即“prototype” ConfigurableBeanFactory.SCOPE_SINGLETON，即“singleton” WebApplicationContext.SCOPE_REQUEST，即“request” WebApplicationContext.SCOPE_SESSION，即“session”
afterPropertiesSet() 在 @Value 完成之后执行
package cn.netkiller.services;
import lombok.Data;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;
@Service
@Data
@Slf4j
public class TestService implements InitializingBean {
private String appId;
public TestService(@Value("${app.id}") String appId) {
this.appId = appId;
log.info(this.appId);
}
@Override
public void afterPropertiesSet() throws Exception {
log.info(this.appId);
}
}