Spring之初识Spring——详述lazy-init作用

 

lazy-init

UserInfo.java

package com.jd.vo;

public class UserInfo {
	
	public UserInfo() {
		System.out.println("构造方法");
	}

}

 

含两个属性值true、false(默认)

1. lazy-init="false",即

application.xml

<?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="userInfo" class="com.jd.vo.UserInfo" lazy-init="false"></bean>
</beans>

 Test.java

package com.jd.test;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test {

	public static void main(String[] args) {
		
		new ClassPathXmlApplicationContext("application.xml");//创建IOC容器，并为Spring配置文件中的配置类创建对象
	}

}

console: 构造方法 

默认在创建IOC容器时自动创建该类的对象

2. lazy-init="true"

application.xml

<?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="userInfo" class="com.jd.vo.UserInfo" lazy-init="true"></bean>
</beans>

 Test.java

（1）

package com.jd.test;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test {

	public static void main(String[] args) {
		
		new ClassPathXmlApplicationContext("application.xml");//创建IOC容器，并为Spring配置文件中的配置类创建对象
	}

}

console：

（2） 

 

package com.jd.test;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test {

	public static void main(String[] args) {

		ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("application.xml");
		applicationContext.getBean("userInfo");
		applicationContext.close();

	}

}

 console: 构造方法 

该属性的值设置为true，则IOC容器创建时便不会创建该类的对象，而是在调用getBean方法时才会创建对象