Spring02：构造器注入

目的：使用spring得到一个已经注入属性的对象

1. 导入依赖

   
       org.springframework
       spring-context
       5.3.9
   
   
   
   
       junit
       junit
       4.13.1
       test
   
   

2. 写实体类

   package com.xxx.pojo;
   
   public class Dog {
       String name;
       int age;
   
       public Dog(String name, int age) {
           this.name = name;
           this.age = age;
       }
   
       @Override
       public String toString() {
           return "Dog{" +
                   "name='" + name + ''' +
                   ", age=" + age +
                   '}';
       }
   }
   
   

3. 写xml文件

   constructor-arg标签可以使用三种方式

   name/type/index

   也就是名字，参数类型，索引

   当然如果参数类型一样则玩不转了

4. 写测试类

   import com.xxx.pojo.Dog;
   import org.junit.Test;
   import org.springframework.context.support.ClassPathXmlApplicationContext;
   
   public class MyTest {
       @Test
       public void test01() {
           ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("bean.xml");
           Dog dog = context.getBean("dog", Dog.class);
           System.out.println(dog);
       }
   }