spring的Bean的生命周期

Posted 2020-11-19 北宫乾宇

Bean的生命周期：

　　　定义　　　　就是在xml文件中定义<bean>子标签，定义某个类的对象需要使用bean进行自动管理注入

　　　初始化　　　就是使用获取一个Bean容器context,然后使用context调用start方法进行初始化

　　　使用　　　　就是获取对应bean中的实例

　　　销毁　　　　就是bean不需要在使用的时候对bean相关的资源信息进行销毁

初始化+销毁

　　方法一

　　

　　案例(使用了JUnit4进行测试)

　

package org.bean.example;

public class BeanLifeCycle {
    
    public void start(){
        System.out.println("bean start");
    }
    public void stop(){
        System.out.println("bean stop");
    }
}

package org.bean.example;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.BlockJUnit4ClassRunner;
import org.util.test.UnitTestBase;

@RunWith(BlockJUnit4ClassRunner.class)
public class TestBeanLifeCycle extends UnitTestBase{
    
    public TestBeanLifeCycle() {
        super("classpath*:spring-life.xml");
    }
    
    @Test
    public void test(){
        super.getBean("beanLifeCycle");
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<beans
    xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:p="http://www.springframework.org/schema/p"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd" xmlns:tx="http://www.springframework.org/schema/tx">

    <bean id="beanLifeCycle" class="org.bean.example.BeanLifeCycle" init-method="start" destroy-method="stop"></bean>
</beans>

 

　

 　方法二

　　案例

 

package org.bean.example;

import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;

public class BeanLifeCycle implements InitializingBean,DisposableBean{
    
    /*public void start(){
        System.out.println("bean start");
    }
    public void stop(){
        System.out.println("bean stop");
    }*/
    
    @Override
    public void afterPropertiesSet() throws Exception {
        System.out.println("bean afterPropertiesSet");
    }
    
    @Override
    public void destroy() throws Exception {
        System.out.println("bean destroy");
    }
}

package org.bean.example;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.BlockJUnit4ClassRunner;
import org.util.test.UnitTestBase;

@RunWith(BlockJUnit4ClassRunner.class)
public class TestBeanLifeCycle extends UnitTestBase{
    
    public TestBeanLifeCycle() {
        super("classpath*:spring-life.xml");
    }
    
    @Test
    public void test(){
        super.getBean("beanLifeCycle");
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<beans
    xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:p="http://www.springframework.org/schema/p"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd" 
    xmlns:tx="http://www.springframework.org/schema/tx">

    <bean id="beanLifeCycle" class="org.bean.example.BeanLifeCycle"></bean>
</beans>

方法三：直接在xml文件中的beans头中添加两个属性即可---default-init-method="方法名"，default-destroy-method="方法名"，然后再相应的bean文件中添加属性的定义的方法

<?xml version="1.0" encoding="UTF-8"?>
<beans
    xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:p="http://www.springframework.org/schema/p"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd" 
    xmlns:tx="http://www.springframework.org/schema/tx"
    default-init-method="defaultInit" default-destroy-method="defaultDestroy">

    <bean id="beanLifeCycle" class="org.bean.example.BeanLifeCycle" ></bean>
</beans>

package org.bean.example;

import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;

public class BeanLifeCycle {
    
    public void defaultInit(){
        System.out.println("bean defaultInit");
    }
    public void defaultDestroy(){
        System.out.println("bean defaultDestroy");
    }
}

package org.bean.example;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.BlockJUnit4ClassRunner;
import org.util.test.UnitTestBase;

@RunWith(BlockJUnit4ClassRunner.class)
public class TestBeanLifeCycle extends UnitTestBase{
    
    public TestBeanLifeCycle() {
        super("classpath*:spring-life.xml");
    }
    
    @Test
    public void test(){
        super.getBean("beanLifeCycle");
    }
}

注意：

　　三个方法的使用可以同时存在，其调用优先级从高到低：实现接口、在Bean中设置init-method、destroy-method属性、在Beans标签头部中添加默认初始化属性(如果存在前面任意一种方法，则该方法就不会执行，并且该方法是设置了所有bean的默认初始化方法)