Spring学习-Spring03-singleton bean与prototype bean

Spring03-singleton bean与prototype bean

1. singleton bean

• singleton是bean的默认值。只要bean的id相同，随便拿多次，还是同一个对象。该单个实例存储在缓存中,对该bean所有以后请求和引用都将返回这个缓存中的对象实例。可以更好的重用对象,节省了重复创建对象的开销.如果id不同，则拿到的对象不一样。
  • id相同时：

    <?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
       		 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    		 xsi:schemaLocation="
            http://www.springframework.org/schema/beans 
    		http://www.springframework.org/schema/beans/spring-beans.xsd">
    	<bean id="someService1" class="com.caorui.service.impl.SomeServiceImpl"></bean>
    	<bean id="someService2" class="com.caorui.service.impl.SomeServiceImpl"></bean>
    </beans>
    

    @Test
    public void testSome01() {
    	//创建容器对象,ApplicationContext初始化时，所有容器中beans创建完毕
    	ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
    	SomeService service1 = ac.getBean("someService1", SomeService.class);
    	SomeService service2 = ac.getBean("someService1", SomeService.class);
    	System.out.println(service1 == service2); //ture
    }
    

  • id不同时：

    <?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
       		 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    		 xsi:schemaLocation="
            http://www.springframework.org/schema/beans 
    		http://www.springframework.org/schema/beans/spring-beans.xsd">
    	<bean id="someService1" class="com.caorui.service.impl.SomeServiceImpl"></bean>
    	<bean id="someService2" class="com.caorui.service.impl.SomeServiceImpl"></bean>
    </beans>
    

    @Test
    public void testSome01() {
    	//创建容器对象,ApplicationContext初始化时，所有容器中beans创建完毕
    	ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
    	SomeService service1 = ac.getBean("someService1", SomeService.class);
    	SomeService service2 = ac.getBean("someService2", SomeService.class);
    	System.out.println(service1 == service2); //false
    }
    

2. prototype bean

• IoC容器导致每次对该特定的bean请求时创建一个新的bean实例.从某种意义上来说,Spring容器在prototype bean上的作用等同于java的new操作符。
  • id相同时：

    <?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
       		 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    		 xsi:schemaLocation="
            http://www.springframework.org/schema/beans 
    		http://www.springframework.org/schema/beans/spring-beans.xsd">
    	<bean id="someService1" class="com.caorui.service.impl.SomeServiceImpl" scope="prototype"></bean>
    	<bean id="someService2" class="com.caorui.service.impl.SomeServiceImpl"></bean>
    </beans>
    

    @Test
    public void testSome01() {
    	//创建容器对象,ApplicationContext初始化时，所有容器中beans创建完毕
    	ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
    	SomeService service1 = ac.getBean("someService1", SomeService.class);
    	SomeService service2 = ac.getBean("someService1", SomeService.class);
    	System.out.println(service1 == service2); //false
    }
    

  • id不同时：

    <?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
       		 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    		 xsi:schemaLocation="
            http://www.springframework.org/schema/beans 
    		http://www.springframework.org/schema/beans/spring-beans.xsd">
    	<bean id="someService1" class="com.caorui.service.impl.SomeServiceImpl" scope="prototype"></bean>
    	<bean id="someService2" class="com.caorui.service.impl.SomeServiceImpl"></bean>
    </beans>
    

    @Test
    public void testSome01() {
    	//创建容器对象,ApplicationContext初始化时，所有容器中beans创建完毕
    	ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
    	SomeService service1 = ac.getBean("someService1", SomeService.class);
    	SomeService service2 = ac.getBean("someService2", SomeService.class);
    	System.out.println(service1 == service2); //false
    }