bean的實例化方式

spring中bean的實例化方式有三種，1.構造器實例化，2.實例工廠實例化，3.靜態工廠實例化spring

1.構造器實例化方式app

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

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

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

2.靜態工廠實例化bean

public class Bean2 {
    public Bean2() {
    }
}

//靜態工廠類
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"/>
測試:

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.實例工廠實例化bean

public class bean3 {
}
實例工廠類

public class MyBeanFactory {
    public MyBeanFactory() {
        System.out.println("這是實例化工廠實例化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"/>
測試

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);    }}