Spring IOC创建对象的两种方式

public class User {
  private String name;

  public User() {
    System.out.println("执行了User类的无参构造方法~");
  }

  public User(String name){
    this.name = name;
    System.out.println("执行了User类的有参构造方法");
  }

  //使用无参构造方法时，必须要设置set方法，因为注入时 需要通过set方法注入
  public void setName(String name) {
    this.name = name;
  }

  @Override
  public String toString() {
    return "User{" +
        "name='" + name + '\'' +
        '}';
  }
}

<?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
    https://www.springframework.org/schema/beans/spring-beans.xsd">

  <bean id="user" class="com.test.pojo.User">
    <property name="name" value="gyp"/>
  </bean>

</beans>

public class MyTest {
  public static void main(String[] args) {
    ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
    User user = context.getBean("user", User.class);
    System.out.println(user);
  }
}

	<bean id="user" class="com.test.pojo.User">
    <constructor-arg index="0" value="gyp"/>
  </bean>

  <bean id="user" class="com.test.pojo.User">
    <constructor-arg name="name" value="gyp"/>
  </bean>

	<bean id="user" class="com.test.pojo.User">
    <constructor-arg type="java.lang.String" value="gyp"/>
  </bean>