什么时候调用 spring beans 销毁方法？

Question

我在 bean 的“destroy-method”中添加了一条 sysout 语句。当我运行示例代码时，sysout 没有得到输出。这是否意味着销毁方法没有被调用？

测试类：

  package spring.test;

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

  public class InitTest {
    public static void main(String[] args) {
        ApplicationContext ctx = new ClassPathXmlApplicationContext("InitTestContext.xml");
        InitTestBean bean = (InitTestBean)ctx.getBean("InitTestBean");
        bean.display();
    }
  }

豆子

  package spring.test;

  public class InitTestBean {
    private String prop1;
    private String prop2;

    public InitTestBean(String prop1, String prop2) {
        System.out.println("Instantiating InitTestBean");
        this.prop1 = prop1;
        this.prop2 = prop2;
    }

    public void setProp1(String prop1) {
        System.out.println("In setProp1");
        this.prop1 = prop1;
    }

    public void setProp2(String prop2) {
        System.out.println("In setProp2");
        this.prop2 = prop2;
    }

    public String getProp1() {
        return prop1;
    }

    public String getProp2() {
        return prop2;
    }

    public void display() {
        System.out.println("Prop1 is " + prop1);
        System.out.println("Prop2 is " + prop2);
    }

    public void initialize(){
        System.out.println("In initialize");
        this.prop1 = "init-prop1";
        this.prop2 = "init-prop2";
    }

    public void teardown() {
        System.out.println("In teardown");
        this.prop1 = null;
        this.prop2 = null;
    }
  }

配置文件：

<?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:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">

    <bean id="InitTestBean" class="spring.test.InitTestBean" init-method="initialize" destroy-method="teardown">
        <constructor-arg value="Prop1" />
        <constructor-arg value="Prop2" />
        <property name="prop1" value="setProp1"/>
        <property name="prop2" value="setProp2"/>
    </bean>

</beans>

Answer 1

factory.destroySingletons(); 在 bean.display() 之后，因为 destroy-method 在 bean 定义中被赋值。创建 bean 的默认作用域是单例，因此，调用 factory.destroySingletons() 将调用 destroy-method 中提到的方法。

Answer 2

只有当且仅当 bean 是单例实例时才会调用“destroy-method”

查看IOC容器的日志输出

INFO：销毁单例 in org.springframework.beans.factory.support.DefaultListableBeanFactory@1a0ce4c：定义bean [book1]；工厂层次结构的根

Answer 3

您好，您需要将ApplicationContext 更改为AbstractApplicationContext，然后注册到ShutDownhook，这将破坏您的bean 并实现DisposableBean 接口，例如：

  package spring.test;

  import org.springframework.context.ApplicationContext;
  import org.springframework.context.support.ClassPathXmlApplicationContext;
  import org.springframework.context.support.AbstractApplicationContext;
  public class InitTest {
    public static void main(String[] args) {
       AbstractApplicationContext ctx = new ClassPathXmlApplicationContext("InitTestContext.xml");
  ctx.registerShutdownHook();
        InitTestBean bean = (InitTestBean)ctx.getBean("InitTestBean");
        bean.display();
    }
  }

现在实现 DisposableBean 接口

package spring.test;
import org.springframework.beans.factory.DisposableBean;
  public class InitTestBean implements DisposableBean{
    private String prop1;
    private String prop2;
    public InitTestBean(String prop1, String prop2) {
        System.out.println("Instantiating InitTestBean");
        this.prop1 = prop1;
        this.prop2 = prop2;
    }
    public void setProp1(String prop1) {
        System.out.println("In setProp1");
        this.prop1 = prop1;
    }
    public void setProp2(String prop2) {
        System.out.println("In setProp2");
        this.prop2 = prop2;
    }
    public String getProp1() {
        return prop1;
    }
    public String getProp2() {
        return prop2;
    }
    public void display() {
        System.out.println("Prop1 is " + prop1);
        System.out.println("Prop2 is " + prop2);
    }
    public void initialize(){
        System.out.println("In initialize");
        this.prop1 = "init-prop1";
        this.prop2 = "init-prop2";
    }
    public void teardown() {
        System.out.println("In teardown");
        this.prop1 = null;
        this.prop2 = null;
    }
    @Override
    public void destroy() throws Exception {

        System.out.println(" the bean has been destroyed");
    }
  }

Answer 4

//Getting application context
ApplicationContext context = new ClassPathXmlApplicationContext(beansXML); 

//cleaning context
((ClassPathXmlApplicationContext) context).close(); 

Answer 5

对于 OP 来说可能为时已晚，但如果有人还在寻找它...

close 方法是在AbstractApplicationContext 而不是ApplicationContext，还有另一种方法是使用ctx.registerShutdownHook() instead of ctx.close()，原因很明显，在运行Junits 时，您可能想要关闭上下文，但在生产环境，所以让 Spring 决定何时关闭它。

Answer 6

您的示例不起作用，因为您没有关闭 appcontext，您只是让程序终止。

在上下文中调用close()，你会看到bean destroy-methods被调用。