bean的实例化方式

spring中bean的实例化方式有三种，1.构造器实例化，2.实例工厂实例化，3.静态工厂实例化

1.构造器实例化方式

public class bean1 {
    public bean1() {
    }
}
applicatContext.xml中的配置

<bean id="bean1" class="com.itheima.ioc.Constructorbean.bean1"/>
测试

public class consTest {
    public static void main(String[] args) {
        ApplicationContext applicationContext=new ClassPathXmlApplicationContext("applicationContext.xml");
        bean1 bean=(bean1) applicationContext.getBean("bean1");
    }
}

2.静态工厂实例化bean

public class Bean2 {
    public Bean2() {
    }
}

//静态工厂类
public class MyFactoryBean2 {
    public static Bean2 creatBean() {
        return new Bean2();
    }
}

applicatContext.xml中的配置

<bean id="bean2" class="com.itheima.ioc.StaticFactoryshilihuaBean2.MyFactoryBean2"
      factory-method="creatBean"/>
测试:

public class TestFactoryBean {
    public static void main(String[] args) {
        ApplicationContext applicationContext=new ClassPathXmlApplicationContext("applicationContext.xml");
        Bean2 bean2=(Bean2)applicationContext.getBean("bean2");
        System.out.println(bean2);
    }
}
3.实例工厂实例化bean

public class bean3 {
}
实例工厂类

public class MyBeanFactory {
    public MyBeanFactory() {
        System.out.println("这是实例化工厂实例化bean...");
    }

    public bean3 createBeanFactory() {
        return new bean3();
    }
}
applicationContext.xml中的配置

 <bean id="MybeanFactory" class="com.itheima.ioc.shiligongcshilihBean3.MyBeanFactory"/>
  <bean id="bean3" factory-bean="MybeanFactory" factory-method="createBeanFactory"/>
测试

public class shilihuabeanTest {
    public static void main(String[] args) {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
        bean3 bean=(bean3)applicationContext.getBean("bean3");
        System.out.println(bean);
    }
}