Spring注解@Scope

Spring注解@Scope 一、@Scope注解 1、@Scope注解作用

@Scope注解用于设置实例的作用域。

默认值是单实例，即当IOC容器启动后就调用该方法创建对象放到IOC容器中，以后每次获取就是直接从容器中获取。

2、@Socpe注解的值

  多实例：IOC容器启动并不会调用方法创建对象放在容器中。每次获取的时候才会调用方法创建对象
 @see ConfigurableBeanFactory#SCOPE_PROTOTYPE    ->  prototype

  单实例（默认值）：IOC容器启动后就调用该方法创建对象放到IOC容器中，以后每次获取就是直接从容器中获取
 @see ConfigurableBeanFactory#SCOPE_SINGLETON    ->  singleton

      
下面两个值用于web应用：
  同一次请求创建一个实例
 @see org.springframework.web.context.WebApplicationContext#SCOPE_REQUEST   ->  request

  同一个session创建一个实例* @see org.springframework.web.context.WebApplicationContext#SCOPE_SESSION   ->  session

3、标注位置

​ 可标注在类和方法上

4、源码查看

二、@Scope注解单实例案例 1、项目结构

2、Persion实体

public class Persion {


    private String name;

    private int age;


    public Persion(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "Persion{" +
                "name='" + name + ''' +
                ", age=" + age +
                '}';
    }
}

3、Bean注册配置类

import com.dashu.bean.Persion;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.context.annotation.*;


@Configuration
public class BeanConfig {


    

    @Scope
    @Bean
    public Persion persion(){
        return new Persion("张三",20);
    }

}

4、测试类

import com.dashu.bean.Persion;
import com.dashu.config.BeanConfig;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;


public class Main {

    public static void main(String[] args) {
        
        AnnotationConfigApplicationContext annotationConfigApplicationContext = new AnnotationConfigApplicationContext(BeanConfig.class);

        Persion persion1 = (Persion) annotationConfigApplicationContext.getBean("persion");

        Persion persion2 = (Persion) annotationConfigApplicationContext.getBean(Persion.class);

        
        System.out.println(persion1 == persion2);

        
    }

}

5、测试结果

三、@Scope注解多实例案例 1、Bean注册配置类

import com.dashu.bean.Persion;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.context.annotation.*;


@Configuration
public class BeanConfig {


    

    @Scope("prototype")
    @Bean
    public Persion persion(){
        return new Persion("张三",20);
    }

}

2、测试类

import com.dashu.bean.Persion;
import com.dashu.config.BeanConfig;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;


public class Main {

    public static void main(String[] args) {

        AnnotationConfigApplicationContext annotationConfigApplicationContext = new AnnotationConfigApplicationContext(BeanConfig.class);

        Persion persion1 = (Persion) annotationConfigApplicationContext.getBean("persion");

        Persion persion2 = (Persion) annotationConfigApplicationContext.getBean(Persion.class);

        
        System.out.println(persion1 == persion2);
        
    }

}

3、测试结果

四、使用注解@ComponentScan开启包扫描，在类上标注注解@Scope（多实例）案例 1、Persion实体

import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Service;



@Scope("prototype")
@Component
public class Persion {


    private String name;

    private int age;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "Persion{" +
                "name='" + name + ''' +
                ", age=" + age +
                '}';
    }
}

2、Bean注册配置类

import com.dashu.bean.Persion;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.context.annotation.*;

@Configuration
@ComponentScan(value = "com.dashu")
public class BeanConfig {

}

3、测试类

import com.dashu.bean.Persion;
import com.dashu.config.BeanConfig;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class Main {

    public static void main(String[] args) {

        AnnotationConfigApplicationContext annotationConfigApplicationContext = new AnnotationConfigApplicationContext(BeanConfig.class);

        Persion persion1 = (Persion) annotationConfigApplicationContext.getBean("persion");

        Persion persion2 = annotationConfigApplicationContext.getBean(Persion.class);

        
        System.out.println(persion1 == persion2);

    }

}

4、测试结果