03点睛Spring4.1-scope
转载:https://www.iteye.com/blog/wiselyman-2210377
3.1 scope
- scope描述spring容器是怎么样新建类的实例的(bean);
- 在spring中默认的scope是singleton,这意味着无论你在程序中多少地方使用这个bean,它们都共享唯一个实例;
- spring内置的scope有如下几个:
- singleton:一个spring容器中只有一个bean的实例;
- prototype:每次调用新建一个bean的实例;
- request:web项目中,每一个http request,新建一个bean实例;
- session:web项目中,每一个http session,新建一个bean实例;
- globalSession:这个只在portal应用中有用,每一个global http session,新建一个bean实例
3.2 演示
3.2.1 新建scope为singleton的类
package com.wisely.scope;
import org.springframework.stereotype.Service;
@Service//默认scope为singleton
public class DemoSingletonService {
}
3.2.2 新建scope为prototype的类
package com.wisely.scope;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Service;
@Service
@Scope("prototype")
public class DemoPrototypeService {
}
3.2.3 测试
package com.wisely.scope;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class Main {
public static void main(String[] args) {
AnnotationConfigApplicationContext context =
new AnnotationConfigApplicationContext("com.wisely.scope");
//分别从spring容器里获得两次实例,为singleton时共享一个实例,用prototype是又新建了一个实例
DemoSingletonService s1 = context.getBean(DemoSingletonService.class);
DemoSingletonService s2 = context.getBean(DemoSingletonService.class);
DemoPrototypeService p1 = context.getBean(DemoPrototypeService.class);
DemoPrototypeService p2 = context.getBean(DemoPrototypeService.class);
System.out.println("s1与s2是否相等:"+s1.equals(s2));
System.out.println("p1与p2是否相等:"+p1.equals(p2));
context.close();
}
}
输出
s1与s2是否相等:true
p1与p2是否相等:false