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Spring创建对象的几种方式
一 :默认构造方法创建对象
1.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-2.5.xsd">
<bean id="helloWorld" class="com.spring.createobject.method.HelloWord"></bean>
</beans>
2.测试类
package com.spring.createobject.method;
public class HelloWord {
public HelloWord(){
System.out.println("create object");
}
public void hello(){
System.out.println("hello word!");
}
}
3,测试
/**
* 在Spring容器中，默认情况下调用了一个类的默认构造函数创建对象
*/
@Test
public void testCreateObject_Default(){
//启动Spring容器
ApplicationContext context=
new ClassPathXmlApplicationContext("applicationContext.xml");
//根据id把Spring容器中的bean提取出来
HelloWord helloWord = (HelloWord) context.getBean("helloWorld");
helloWord.hello();
}
输出:
create object
hello word!
二:静态工厂创建对象
1.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-2.5.xsd">
<!-- factory-method 指的是静态工厂方法-->
<bean id="helloWord2" class="com.spring.createobject.method.factory.HelloWordFactory"
factory-method="getInstance"></bean>
</beans>
2.测试类
package com.spring.createobject.method;
public class HelloWord {
public HelloWord(){
System.out.println("create object");
}
public void hello(){
System.out.println("hello word!");
}
}
package com.spring.createobject.method.factory;
import com.spring.createobject.method.HelloWord;
//静态工厂方法
public class HelloWordFactory {
public static HelloWord getInstance(){
return new HelloWord();
}
}
3.测试
/**
*
* 利用静态工厂模式创建对象
* <bean id="helloWord2" class="com.spring.createobject.method.factory.HelloWordFactory"
factory-method="getInstance"></bean>
Spring容器内部调用了HelloWordFactory中的getInstance方法创建对象
而具体的new对象的过程由程序员完成的。
*/
@Test
public void testCreateObject_StaticFactory(){
//启动Spring容器
ApplicationContext context=
new ClassPathXmlApplicationContext("applicationContext.xml");
//根据id把Spring容器中的bean提取出来
HelloWord helloWord = (HelloWord) context.getBean("helloWord2");
helloWord.hello();
}
输出:
create object
hello word!
三:实例工厂创建对象
1.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-2.5.xsd">
<bean id="hellowordFactory"
class="com.spring.createobject.method.factory.HelloWordFactory2"></bean>
<!-- factory-bean 是一个工厂bean,会调用hellowordFactory所指向的对象，再调用getInstance创建对象
factory-method 是一个工厂方法
-->
<bean id="helloword3"
factory-bean="hellowordFactory"
factory-method="getInstance"></bean>
</beans>
2.测试类
package com.spring.createobject.method;
public class HelloWord {
public HelloWord(){
System.out.println("create object");
}
public void hello(){
System.out.println("hello word!");
}
}
package com.spring.createobject.method.factory;
import com.spring.createobject.method.HelloWord;
public class HelloWordFactory2 {
public HelloWord getInstance(){
return new HelloWord();
}
}
3.测试
/**
* 实例工厂方法
*/
@Test
public void testCreateObject_instancecFactory(){
//启动Spring容器
ApplicationContext context=
new ClassPathXmlApplicationContext("applicationContext.xml");
//根据id把Spring容器中的bean提取出来
HelloWord helloWord = (HelloWord) context.getBean("helloword3");
helloWord.hello();
}
输出:
create object
hello word!
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原文地址：http://www.cnblogs.com/thinkpad/p/4928274.html
