Spring 高级 Scope

介绍

1、在当前版本的 Spring 和 Spring Boot 程序中，支持五种 Scope

  • singleton，容器启动时创建（未设置延迟），容器关闭时销毁
  • prototype，每次使用时创建，不会自动销毁，需要调用 DefaultListableBeanFactory.destroyBean(bean) 销毁
  • request，每次请求用到此 bean 时创建，请求结束时销毁
  • session，每个会话用到此 bean 时创建，会话结束时销毁
  • application，web 容器用到此 bean 时创建，容器停止时销毁

2、有些文章提到有 globalSession 这一 Scope，也是陈旧的说法，目前 Spring 中已废弃

但要注意，如果在 singleton 注入其它 scope 都会有问题，解决方法

request, session, application 作用域

1、代码

package com.mangoubiubiu.show.a08;

import lombok.extern.slf4j.Slf4j;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component;

import javax.annotation.PreDestroy;

@Scope("application")
@Component
@Slf4j
public class BeanForApplication {

    @PreDestroy
    public void destroy(){
        log.info("destroy");
    }

}
package com.mangoubiubiu.show.a08;

import lombok.extern.slf4j.Slf4j;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component;

import javax.annotation.PreDestroy;

@Scope("request")
@Component
@Slf4j
public class BeanForRequest {

    @PreDestroy
    public void destory(){
        log.info("destory");
    }
}
package com.mangoubiubiu.show.a08;


import lombok.extern.slf4j.Slf4j;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component;

import javax.annotation.PreDestroy;

@Scope("session")
@Component
@Slf4j
public class BeanForSession {


    @PreDestroy
    public void destroy(){
        log.info("destory");
    }


}
package com.mangoubiubiu.show.a08;


import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Lazy;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

@RestController
public class MyController {


    @Lazy
    @Autowired
    private BeanForRequest beanForRequest;


    @Autowired
    @Lazy
    private BeanForSession beanForSession;


    @Autowired
    @Lazy
    private BeanForApplication beanForApplication;




    @GetMapping(value = "/test", produces = "text/html")
    public String test(HttpServletRequest request, HttpSession session) {
        ServletContext sc = request.getServletContext();
        String sb = "<ul>" +
                "<li>" + "request scope:" + beanForRequest + "</li>" +
                "<li>" + "session scope:" + beanForSession + "</li>" +
                "<li>" + "application scope:" + beanForApplication + "</li>" +
                "</ul>";
        return sb;
    }



}
package com.mangoubiubiu.show.a08;


import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;

@SpringBootApplication(exclude = DataSourceAutoConfiguration.class)
public class A08Application {

    public static void main(String[] args) {
        SpringApplication.run(A08Application.class,args);
    }

}

刷新一下会发现request域对象变了

用另外一个匿名窗口访问发现session域对象变了

重启应用发现application域对象变了

 

 

 

 

 

posted @ 2022-09-20 22:02  KwFruit  阅读(34)  评论(0)  编辑  收藏  举报