Sping three kinds of ways to instantiate Bean

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Three kinds of ways to instantiate Bean

1. instantiated class constructor (no default parameter)
2. Example of a static factory method (simple factory pattern)
3. Examples of the method of Example plant (factory methods)

Code shows
applicationContext.xml configuration is as follows:

<?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.xsd">
    <!-- Bean实例化三种方式 -->
    <!-- 第一种：.使用类构造器实例化（ 默认无参数） -->
    <bean id="bean1" class="com.shunli.ioc.demo1.Bean1"></bean>
    <!-- 第二种：使用静态工厂方法实例化（简单工厂模式） -->
    <bean id="bean2" class="com.shunli.ioc.demo1.Bean2Factory" factory-method="createBean2"></bean>    
    <!-- 第三种：使用实例工厂方法实例化（工厂方法模式） -->
    <bean id="bean3Factory" class="com.shunli.ioc.demo1.Bean3Factory"></bean> 
    <bean id="bean3" factory-bean="bean3Factory" factory-method="createBean3"></bean>    
</beans>

First: use the instance of the class constructor (no default parameter)

package com.shunli.ioc.demo1;

/**
 * Bean的实例化三中方式：1.使用类构造器实例化（ 默认无参数）
 * @author shunli
 *  
 */
public class Bean1 {
	public Bean1() {
		System.out.println("Bean1被实例化了...");
		
	}
}

demo：

package com.shunli.ioc.demo1;

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

/**
 *  Bean实例化三种方式：1.使用类构造器实例化（ 默认无参数）
 * @author shunli
 *
 */
public class TestMain {
	
	@Test
	public void demo1() {
		//创建工厂
		ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
		//通过工厂获得类的实例
		Bean1 bean1 =  (Bean1)applicationContext.getBean("bean1");
	}
}

The second: using a static factory method to instantiate (simple factory pattern)

package com.shunli.ioc.demo1;

/**
 *  Bean的实例化三中方式：2、使用静态工厂方法实例化（简单工厂模式）
 * @author shunli
 *
 */
public class Bean2 {
	
}

---

package com.shunli.ioc.demo1;

/**
 * Bean2的静态工厂
 * @author shunli
 *
 */
public class Bean2Factory {

	public static Bean2 createBean2() {
		System.out.println("Bean2Factory");
		return new Bean2();
	}
}

---

In the demo:

package com.shunli.ioc.demo1;

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

/**
 *  Bean实例化三种方式：2、使用静态工厂方法实例化（简单工厂模式）
 * @author shunli
 *
 */
public class TestMain {
	@Test
	public void demo2() {
		//创建工厂
		ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
		//通过工厂获得类的实例
		Bean2 bean2 =  (Bean2)applicationContext.getBean("bean2");
	}
}

Third, the method of Example of Example plant (factory methods)

package com.shunli.ioc.demo1;

/**
 * Bean的实例化三中方式：3、使用实例工厂方法实例化（工厂方法模式）
 * @author shunli
 *
 */
public class Bean3 {
	
}

---

package com.shunli.ioc.demo1;

/**
 * Bean3实例工厂
 * @author shunli
 *
 */
public class Bean3Factory {
	public Bean3 createBean3() {
		System.out.println("Bena3工厂被执行了");
		return new Bean3();
		
	}
}

---

package com.shunli.ioc.demo1;

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

/**
 *  Bean实例化三种方式
 * @author shunli
 *
 */
public class TestMain {
	@Test
	public void demo3() {
		//创建工厂
		ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
		//通过工厂获得类的实例
		Bean3 bean3 =  (Bean3)applicationContext.getBean("bean3");
	}

}