Bean的装配方式---XML---构造注入

朱雀 2023-06-07 08:06 66阅读 0赞

User实体类

package com.student.assemble;
    
    import java.util.List;
    
    public class User {
    	private String username;
    	private Integer password;
    	private List <String> list;
    	//Source + Generate Constructor using Fields 自动生成构造方法
    	public User(String username, Integer password, List<String> list) {
    		super();
    		this.username = username;
    		this.password = password;
    		this.list = list;
    	}
    	@Override
    	public String toString() {
    		return "User [username=" + username + ", password=" + password + ", list=" + list + "]";
    	}
    	
    }

bean5配置文件

<?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 id="user1" class="com.student.assemble.User">
    		<constructor-arg index = "0" value = "tom"></constructor-arg>
    		<constructor-arg index = "1" value = "123456"></constructor-arg>
    		<constructor-arg index = "2" >
    			<list>
    				<value>"我爱你"</value>
    				<value>"我也爱你"</value>
    			</list>
    		</constructor-arg>
    	</bean>
    </beans>

XmlBeanAssembleTest：测试类

package com.student.assemble;
    
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    import com.student.instance.constructor.Bean1;
    
    public class XmlBeanAssembleTest {
    
    	public static void main(String[] args) {
    		String xmlPath = "com/student/assemble/bean5.xml";
    		ApplicationContext applicationContext =new ClassPathXmlApplicationContext(xmlPath);
    		User user =(User)applicationContext.getBean("user1");
    		System.out.println(user);
    
    	}
    
    }

运行结果：

十月 13, 2019 6:15:06 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
    信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@46f7f36a: startup date [Sun Oct 13 18:15:06 CST 2019]; root of context hierarchy
    十月 13, 2019 6:15:06 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
    信息: Loading XML bean definitions from class path resource [com/student/assemble/bean5.xml]
    User [username=tom, password=123456, list=["我爱你", "我也爱你"]]

理解：测试类在实例化Bean的时候，配置文件的constructor-arg 会通过User的构造方法将User类的属性附上值（这个过程叫做为User装配）。