Spring快速入门

1、引入核心约束

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>cn.kgc</groupId>
    <artifactId>springDemo01_helloworld</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
<!--        引入Spring最核心的依赖-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.0.2.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
    </dependencies>
</project>

2、创建Spring配置文件

　　

<?xml version="1.0" encoding="UTF-8"?>
<!--引入bean的名称空间
    dtd:mybatis
    schema:spring
    http://www.springframework.org/schema/beans/spring-beans.xsd      引入约束-->
<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">
<!--    scope=""单双例的属性    name 属性可以代替id-->
    <bean id="userDao" class="cn.kgc.daoImpl.userDaoImpl" scope="singleton"></bean>
</beans>

3、创建接口

public interface UserDao {
}

4、创建接口实现类

public class userDaoImpl implements UserDao {
    public userDaoImpl(){
        System.out.println("userDao里的空参构造");
    }

5、创建测试类

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

public class TestSpring {
    public static void main(String[] args) {
        // 创建springIOC容器
        ApplicationContext ac = new ClassPathXmlApplicationContext("beans.xml");
        //  获取对象
        Object bean = ac.getBean("userDao");
        System.out.println(bean);
    }
}