创建对象的几种方式

1. 调用无参数构造器
2. 调用有参数构造器
3. 工厂
   静态方法
   <bean id=”’ class=”” factory-method=””/>
   非静态方法
   <bean id=”factory” class=”..”>
   <bean id=”” factory-bean=” factory” factory-method=”实例方法” />
   4. 反射

案例

1. beam.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.xsd">
        
    <!-- 调用无参构造器
    <bean id="user" class="com.xxjqr.spring01.create_obj.User"></bean>
     -->   
    
    
    <!-- 调用有参构造器
    <bean id="user" class="com.xxjqr.spring01.create_obj.User">
        <constructor-arg index="2" type="int" value="22"></constructor-arg>
        <constructor-arg index="0" type="String" value="丁昌江"></constructor-arg>
        <constructor-arg index="1" type="String" value="男"></constructor-arg>
    </bean>
    --> 
    
    
    <!-- 工厂模式-静态方法
        <bean id="user" class="com.xxjqr.spring01.create_obj.UserFactory" factory-method="getStaticInstance"></bean>
     -->
   
    <!-- 工厂模式-非静态方法 -->
    <bean id="factory"  class="com.xxjqr.spring01.create_obj.UserFactory"></bean>
    <bean id="user" factory-bean="factory" class="com.xxjqr.spring01.create_obj.User" factory-method="getInstance"></bean>
  
    
</beans>

类

@Data
@AllArgsConstructor
public class User {
    private String name;
    private String sex;
    private int age;
}

public class UserFactory {
    public static User getStaticInstance(){
        return new User("单身汉","男",20);
    }
    
    public User getInstance(){
        return new User("单身汉","男",20);
    }
}

测试类

public class App {
    private ApplicationContext ac = new ClassPathXmlApplicationContext("bean.xml",App.class);
    
    @Test
    public void testUser() {
        User user = (User) ac.getBean("user");
        System.out.println(user);
    }

}