- 无参数构造
对于这种方式,注意Bean类中必须提供无参数构造。
创建bean类
package com.itcast.bean;
public class Bean1 {
public Bean1(){
System.out.println("bean1的无参构造");
}
public void show(){
System.out.println("bean1 show...");
}
}
在applicationContext.xml配置文件中添加属性
<bean id="bean1" class="com.itcast.bean.Bean1">
测试:
三种方式均可获得bean实例
注意:FileSystemXmlApplicationContext相比ClassPathXmlApplicationContext加载配置文件时要添加src路径
public class BeanTest {
@Test
public void test1() {
//使用beanFactory获取bean1实例
Resource resource = new ClassPathResource("applicationContext.xml");
BeanFactory factory = new XmlBeanFactory(resource);
Bean1 bean1 = (Bean1) factory.getBean("bean1");
bean1.show();
}
@Test
public void Test2() {
//使用ApplicationContext 获取bean1实例
ApplicationContext ApplicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
Bean1 bean1 = (Bean1) ApplicationContext.getBean("bean1");
bean1.show();
}
@Test
public void test3() {
ApplicationContext ApplicationContext = new FileSystemXmlApplicationContext("src/applicationContext.xml");
Bean1 bean1 = (Bean1) ApplicationContext.getBean("bean1");
bean1.show();
}
}
- 静态工厂方法
需要创建一个工厂类,在工厂类中提供一个static返回bean对象的方法就可以。
创建bean2类
package com.itcast.bean2;
public class Bean2 {
public void show(){
System.out.println("hello bean2....");
}
}
创建bean2Factory类
package com.itcast.bean2;
public class Bean2Factory {
public static Bean2 createBean2(){
return new Bean2();
}
}
在applicationContext.xml配置文件中添加属性
<bean id="Bean2Factory" class="com.itcast.bean2.Bean2Factory" factory-method="createBean2"></bean>
测试:
@Test
public void test4(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
Bean2 Bean2 = (Bean2) applicationContext.getBean("Bean2Factory");
Bean2.show();
}
- 实例工厂方法
需要创建一个工厂类,在工厂类中提供一个非static的创建bean对象的方法,在配置文件中需要将工厂配置,还需要配置bean
创建bean3类
package com.itcast.bean3;
public class Bean3 {
public void show(){
System.out.println("hello bean3...");
}
}
创建Bean3Factory类
package com.itcast.bean3;
public class Bean3Factory {
public Bean3 createBean3(){
return new Bean3();
}
}
在applicationContext.xml配置文件中添加属性
<bean name="Bean3Factory" class="com.itcast.bean3.Bean3Factory"></bean>
<bean name="Bean3" factory-bean="Bean3Factory" factory-method="createBean3"></bean>
测试:
@Test
public void test5(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
Bean3 bean3 = (Bean3) applicationContext.getBean("Bean3");
bean3.show();
}