先看下面程式碼：

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)   //單例  多例
    @Bean
    @Lazy //是否在用到的時候再初始化
    public Person getPerson(){
        System.out.println("初始化。。");
        return new Person("xu",25);
    }

//    @Autowired
//    private Person person1;
    @Autowired
    @Lazy //是否在用到的時候再注入
    private Person person2;
}
 

@Bean:  Indicates that a method produces a bean to be managed by the Spring container.  把一個方法產生的bean交給spring管理。

@Scope：表明是單例還是多例注入，有兩個值：

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：表示用到的時候初始化，用到的時候再進行注入

測試類：

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);

    }

}