Spring实现简单IoC

使用Spring框架的​​IoC​​可以通过配置xml和反射机制实现。

下载springframework

​​https://repo.spring.io/ui/repos/tree/Builds/libs-release-local/org/springframework/spring/5.2.9.RELEASE/spring-5.2.9.RELEASE-dist.zip​​​ 或
https://repo.spring.io/ui/native/libs-release-local/org/springframework/spring/5.3.9/

定义接口和实现类

public interface IHello {
    public String sayHello(String name);
}

public class HelloChina implements IHello {
    @Override
    public String sayHello(String name) {
        return "你好， " + name + "先生";
    }
}

public class HelloEnglish implements IHello{
    @Override
    public String sayHello(String name) {
        return "How are you " + name;
    }
}

使用XML配置Bean

在resources目录下新建​​bean.xml​​：

<?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 http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="helloBean" class="HelloChina"></bean>
</beans>

通过实例IoC容器读取Bean

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

public class One {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
        IHello hi = (IHello) context.getBean("helloBean");
        String hello = hi.sayHello("Kitty");
        System.out.printf(hello);
    }
}

配置bean为：​​<bean id="helloBean" class="HelloEnglish"></bean>​​：