Java框架spring Boot学习笔记：基于构造函数的依赖注入

Posted 2020-10-13 pyqb

编写User.java

 1 package com.example.spring;
 2 
 3 public class User {
 4     private String name;
 5     private Integer age;
 6     private String country;
 7 
 8     public User(String name, Integer age, String country) {
 9         this.name = name;
10         this.age = age;
11         this.country = country;
12     }
13 
14     public String toString() {
15         return name + " is " + age + " years old, living in " + country;
16     }
17 }

 

编写Beans.xml

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <beans xmlns="http://www.springframework.org/schema/beans"
 3        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
 5 
 6     <bean id="user" class="com.example.spring.User" >
 7         <constructor-arg name="name" type="java.lang.String" value="Jacky" />
 8         <constructor-arg name="age" type="java.lang.Integer" value="22"/>
 9         <constructor-arg name="country" type="java.lang.String" value="China"/>
10     </bean>
11 
12 </beans>

 

编写Application.java

package com.example.spring;

import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Application {
    public static void main(String[] args) {
        //bean配置文件所在位置 D:\\IdeaProjects\\spring\\src\\Beans.xml
        //使用AbstractApplicationContext容器
        AbstractApplicationContext context = new ClassPathXmlApplicationContext("file:D:\\IdeaProjects\\spring\\src\\Beans.xml");
        User user = (User)context.getBean("user");
        System.out.println(user);
    }
}

 

运行输出

Jacky is 22 years old, living in China