@Scope @Lazy @Bean注解注解

落日映苍穹つ 2022-05-09 00:14 341阅读 0赞

先看下面代码：

package com.xhx.spring.config;
    
    import com.xhx.spring.domain.Person;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.beans.factory.config.ConfigurableBeanFactory;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.context.annotation.Lazy;
    import org.springframework.context.annotation.Scope;
    
    import java.beans.PersistenceDelegate;
    
    @Configuration
    public class ScopeConfig {
    
        @Scope(value = ConfigurableBeanFactory.SCOPE_PROTOTYPE)   //单例  多例
        @Bean
        @Lazy //是否在用到的时候再初始化
        public Person getPerson(){
            System.out.println("初始化。。");
            return new Person("xu",25);
        }
    
    //    @Autowired
    //    private Person person1;
        @Autowired
        @Lazy //是否在用到的时候再注入
        private Person person2;
    }

@Bean:  Indicates that a method produces a bean to be managed by the Spring container.  把一个方法产生的bean交给spring管理。可以用name属性指定注入的名称

@Scope：表明是单例还是多例注入，有两个值：

public interface ConfigurableBeanFactory extends HierarchicalBeanFactory, SingletonBeanRegistry {
    
    	/**
    	 * Scope identifier for the standard singleton scope: "singleton".
    	 * Custom scopes can be added via {@code registerScope}.
    	 * @see #registerScope
    	 */
    	String SCOPE_SINGLETON = "singleton";
    
    	/**
    	 * Scope identifier for the standard prototype scope: "prototype".
    	 * Custom scopes can be added via {@code registerScope}.
    	 * @see #registerScope
    	 */
    	String SCOPE_PROTOTYPE = "prototype";
    
            ....
    }

@Lazy：表示用到的时候初始化，用到的时候再进行注入

测试类：

package com.xhx.spring;
    
    import com.xhx.spring.config.ScopeConfig;
    import com.xhx.spring.domain.Person;
    import org.junit.Test;
    import org.junit.runner.RunWith;
    import org.springframework.boot.test.context.SpringBootTest;
    import org.springframework.context.annotation.AnnotationConfigApplicationContext;
    import org.springframework.test.context.junit4.SpringRunner;
    
    import java.util.Arrays;
    
    @RunWith(SpringRunner.class)
    @SpringBootTest
    public class Spring5ScopeLazyApplicationTests {
    
        @Test
        public void testScope() {
            AnnotationConfigApplicationContext annotationConfigApplicationContext = new AnnotationConfigApplicationContext(ScopeConfig.class);
            Person bean = annotationConfigApplicationContext.getBean(Person.class);
            System.out.println(bean);
            Person bean2 = annotationConfigApplicationContext.getBean(Person.class);
            System.out.println(bean2);
    
        }
    
    }

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