Spring对bean的初始化

在Spring中，Bean的初始化有两种方式：

1、在配置文档中指定init-method属性来完成。

2、实现org.springframework.beans.factory.InitializingBean接口。

第一种方式：

配置文件如下：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE  beans PUBLIC "-//SPRING//DTD BEAN//EN"
"http://www.springframework.org/dtd/spring-beans.dtd">

<beans>
	<bean id="HelloWorld" class="com.example.demo.test.HelloWorld" init-method="init">
	</bean>
</beans>

bean:

package com.example.demo.test;

public class HelloWorld {

	public String msg;

	public void init() {
		msg = "HelloWorld~";
	}

	public String getMsg() {
		return msg;
	}

	public void setMsg(String msg) {
		this.msg = msg;
	}

}

package com.example.demo.test;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;

public class SpringTest {

	public static void main(String[] args) {
		ApplicationContext actx = new FileSystemXmlApplicationContext("src/config/config.xml");
		HelloWorld h = (HelloWorld) actx.getBean("HelloWorld");
		System.out.println(h.getMsg());

	}
}

第二种方式：

配置文件去掉init-method属性

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE  beans PUBLIC "-//SPRING//DTD BEAN//EN"
"http://www.springframework.org/dtd/spring-beans.dtd">

<beans>
	<bean id="HelloWorld" class="com.example.demo.test.HelloWorld">
	</bean>
</beans>

bean:

package com.example.demo.test;

import org.springframework.beans.factory.InitializingBean;

public class HelloWorld implements InitializingBean {

	public String msg;

	public String getMsg() {
		return msg;
	}

	public void setMsg(String msg) {
		this.msg = msg;
	}

	@Override
	public void afterPropertiesSet() throws Exception {
		msg = "HelloWorld~";
	}

}