Bean的实例化

一.构造器实例化

      One.class类：

public class One {
    public void say(){
        System.out.println("我是构造器实例化");
    }
}

　applicationContext.xml:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
                http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">
    <bean id="one" class="cn.chauncey.ioc.One"/>
</beans>

　　Test.class测试类：

public class OneTest {
    public static void main(String[] args) {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
        One one = (One) applicationContext.getBean("one");
        one.say();
    }
}

　　运行结果： 

二.静态工厂方式实例化

Two.class接口：

public interface Two {
     public void say();
}

TwoImp接口的实现类：

public class TwoImpl implements Two {
    @Override
    public void say() {
        System.out.println("我是静态工厂实例化");
    }
}

MyBeanFactory.class类：

public class MyBeanFactory {
    public static TwoImpl createBean(){
        return new TwoImpl();
    }
}

applicationContext.xml:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
                http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">
    <bean id="twoImpl" class="cn.chauncey.ioc.MyBeanFactory" factory-method="createBean"/>
</beans>

TwoTest.class测试类：

public class TwoTest {
    public static void main(String[] args) {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
        TwoImpl two = (TwoImpl) applicationContext.getBean("twoImpl");
        two.say();

    }
}

运行结果：

三.实例工厂方式实例化

Three.class类：

public class Three {
   private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

MyBeanFactory.class类：

public class MyBeanFactory {
    public Three createBean(){
        return new Three();
    }
}

applicationContext.xml:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
                http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">
    <bean id="myBeanFactory" class="cn.chauncey.ioc.MyBeanFactory"/>
    <bean id="three" factory-bean="myBeanFactory" factory-method="createBean">
        <property name="name" value="我是实例工厂方式实例化"/>
    </bean>
</beans>

ThreeTest.class测试类：

public class ThreeTest {
    public static void main(String[] args) {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
        Three three = (Three) applicationContext.getBean("three");
        System.out.println(three.getName());
    }
}

运行效果：