Spring中Bean的作用域与生命周期详解

<!-- singleton单实例bean
  1、在容器创建时被创建
  2、只有一个实例
  -->
<bean id="book02" class="com.spring.beans.Book" scope="singleton"></bean>

@Test
public void test09() {
    // 单实例创建时创建的两个bean相等
    Book book03 = (Book)iocContext3.getBean("book02");
    Book book04 = (Book)iocContext3.getBean("book02");
    System.out.println(book03==book04);
}

<!-- prototype多实例bean
1、在容器创建时不会被创建，
2、只有在被调用的时候才会被创建
3、可以存在多个实例
 -->
<bean id="book01" class="com.spring.beans.Book" scope="prototype"></bean>

@Test
public void test09() {
    // 多实例创建时，创建的两个bean对象不相等
    Book book01 = (Book)iocContext3.getBean("book01");
    Book book02 = (Book)iocContext3.getBean("book01");
    System.out.println(book01==book02);
}

package com.spring.beans;
public class Book {
	private String bookName;
	private String author;
	/**
	 * 初始化方法
	 * */
	public void myInit() {
		System.out.println("book bean被创建");
	}
	/**
	 * 销毁时方法
	 * */
	public void myDestory() {
		System.out.println("book bean被销毁");
	}
	public String getBookName() {
		return bookName;
	}
	public void setBookName(String bookName) {
		this.bookName = bookName;
	}
	public String getAuthor() {
		return author;
	}
	public void setAuthor(String author) {
		this.author = author;
	}
	@Override
	public String toString() {
		return "Book [bookName=" + bookName + ", author=" + author + "]";
	}
	
}

<!-- 设置bean的生命周期
destory-method：结束调用的方法
init-method：起始时调用的方法
 -->
<bean id="book01" class="com.spring.beans.Book" destroy-method="myDestory" init-method="myInit"></bean>

package com.spring.beans;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
/**
 * 测试bean的后置处理器
 * 在这里要注意一点是为了出现bean和beanName，而不是arg0、arg1，需要绑定相应的源码jar包
 * */
public class MyBeanPostProcessor implements BeanPostProcessor{
	/**
	 * postProcessBeforeInitialization
	 * 初始化方法执行前执行
	 * Object bean
	 * String beanName xml容器中定义的bean名称
	 * */
	@Override
	public Object postProcessBeforeInitialization(Object bean, String beanName)
			throws BeansException {
		// TODO Auto-generated method stub
		System.out.println("【"+ beanName+"】初始化方法执行前...");
		return bean;
	}
	/**
	 * postProcessAfterInitialization
	 * 初始化方法执行后执行
	 * Object bean
	 * String beanName xml容器中定义的bean名称
	 * */
	@Override
	public Object postProcessAfterInitialization(Object bean, String beanName)
			throws BeansException {
		// TODO Auto-generated method stub
		System.out.println("【"+ beanName+"】初始化方法执行后...");
		return bean;
	}
}

<!-- 测试bean的后置处理器 -->
<bean id="beanPostProcessor" class="com.spring.beans.MyBeanPostProcessor"></bean>

//*************************bean生命周期*****************
//	由于ApplicationContext是一个顶层接口，里面没有销毁方法close，所以需要使用它的子接口进行接收
	ConfigurableApplicationContext iocContext01 = new ClassPathXmlApplicationContext("ioc1.xml");
	@Test
	public void test01() {
		iocContext01.getBean("book01");
		iocContext01.close();
	}