Spring学习——IOC

Posted 2021-03-23 geekshawn

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Spring的bean管理（注解方式）

1. 示例准备

（1）导入jar包

技术图片

（2）创建类和方法

1 public class User {
2     public void fun() {
3         System.out.println("function");
4     }
5 }

（3）创建spring配置文件并引入约束

在beans约束的基础上，引入context约束。

<?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: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"> 
</beans>

（4）开启注解扫描

<?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: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">
        <!-- 开启注解扫描 -->
            <!-- 到base-package指示的包当中，扫描类、方法、属性上面是否有注解 -->
        <context:component-scan base-package="cn.itcast"></context:component-scan>
</beans>

2. 注解创建对象

1 import org.springframework.stereotype.Component;
2 
3 @Component(value = "user")
4 public class User {
5     public void fun() {
6         System.out.println("function");
7     }
8 }

 1 import org.junit.Test;
 2 import org.springframework.context.ApplicationContext;
 3 import org.springframework.context.support.ClassPathXmlApplicationContext;
 4 
 5 public class TestAnno {
 6     @Test
 7     public void testUser() {
 8         ApplicationContext context = new ClassPathXmlApplicationContext("bean.xml");
 9         User user = (User) context.getBean("user");
10         System.out.println(user);
11         user.fun();
12     }
13 }