spring 创建对象 demo

Posted 2020-10-15

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:p="http://www.springframework.org/schema/p"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">
    
    <!-- ###############对象创建############### -->
    
    <!-- 1. 默认无参数构造器 
    <bean id="user1" class="cn.itcast.b_create_obj.User"></bean>
    -->
    
    <!-- 2. 带参数构造器 -->
    <bean id="user2" class="cn.itcast.b_create_obj.User">
        <constructor-arg index="0" type="int" value="100"></constructor-arg>
        <constructor-arg index="1" type="java.lang.String" value="Jack"></constructor-arg>
    </bean>
    
    <!-- 定义一个字符串，值是"Jack" ;  String s = new String("jack")-->
    <bean id="str" class="java.lang.String">
        <constructor-arg value="Jacks"></constructor-arg>
    </bean>
    <bean id="user3" class="cn.itcast.b_create_obj.User">
        <constructor-arg index="0" type="int" value="100"></constructor-arg>
        <constructor-arg index="1" type="java.lang.String" ref="str"></constructor-arg>
    </bean>
    
    
    <!-- 3. 工厂类创建对象 -->
    <!-- # 3.1 工厂类，实例方法 -->
    <!-- 先创建工厂 -->
    <bean id="factory" class="cn.itcast.b_create_obj.ObjectFactory"></bean>
    <!-- 在创建user对象，用factory方的实例方法 -->
    <bean id="user4" factory-bean="factory" factory-method="getInstance"></bean>
    
    
    <!-- # 3.2 工厂类： 静态方法 -->
    <!-- 
        class 指定的就是工厂类型
        factory-method  一定是工厂里面的“静态方法”
     -->
    <bean id="user" class="cn.itcast.b_create_obj.ObjectFactory" factory-method="getStaticInstance"></bean>
    
    
    <!-- 对象写法 -->
    <!-- 
    问题：spring配置文件中，bean节点的id与name属性的区别?
        id 不能有特殊符号, 且唯一，且不能以数字开始
        name 可以有特殊符号
     -->
    <bean id="test" name="1test"  class="cn.itcast.b_create_obj.User"></bean>
</beans>      

 

 

 

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:p="http://www.springframework.org/schema/p"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">
    

     
    <bean id="user" class="cn.itcast.cproperty.user">    
    <constructor-arg value="100"></constructor-arg>
    <constructor-arg  value="tom"></constructor-arg>
    </bean>

public class app {
private ApplicationContext ac= new ClassPathXmlApplicationContext("cn/itcast/cproperty/bean.xml");

@Test
public void testset() throws Exception{
    user user=(user)ac.getBean("user");
    System.out.println(user);
}

}