2-形象理解SpringIOC（控制反转）

package org.ks.newinstance;

public interface ICourse {
    void learn();        //学习。。。。
}

package org.ks.newinstance;

public class JavaCourse implements ICourse {

    @Override
    public void learn() {
        System.out.println("学习Java");
    }
    
}

package org.ks.newinstance;

public class HtmlCourse implements ICourse {

    @Override
    public void learn() {
        System.out.println("学习HTML");
    }
    
}

package org.ks.entity;

import org.ks.factory.CourseFactory;
import org.ks.newinstance.HtmlCourse;
import org.ks.newinstance.ICourse;
import org.ks.newinstance.JavaCourse;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Student {
    private int stuNo;
    private String stuName;
    private int stuAge;
    public int getStuNo() {
        return stuNo;
    }
    public void setStuNo(int stuNo) {
        this.stuNo = stuNo;
    }
    public String getStuName() {
        return stuName;
    }
    public void setStuName(String stuName) {
        this.stuName = stuName;
    }
    public int getStuAge() {
        return stuAge;
    }
    public void setStuAge(int stuAge) {
        this.stuAge = stuAge;
    }
    @Override
    public String toString() {
        return this.stuName + "," + this.stuAge + "," + this.stuNo;
        }
    
    //学习所有课程
    public void learn(String name)
    {
        /*
        //方式2.
            //从自己编写的简单工厂中国获取课程
        ICourse course = CourseFactory.getCourse(name);//course就是根据name拿到的相应课程
        course.learn();
        */

        //方式3.
        //直接从IOC容器中获取
        //从SpringIOC提供的超级工厂中获取课程（前提：之前设置过Bean）
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        ICourse course = (ICourse)context.getBean(name);
        course.learn();
        
    }
    
    //方式1.
    public void learnjava() {         //学习Java课程
        ICourse course = new JavaCourse();
        course.learn();
    }
    
    //学习HTML课程
    public void learnhtml() {
        ICourse course = new HtmlCourse();
        course.learn();
    }
}

package org.ks.factory;

import org.ks.newinstance.HtmlCourse;
import org.ks.newinstance.ICourse;
import org.ks.newinstance.JavaCourse;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

//课程工厂（用于产生课程）
public class CourseFactory {
    public static ICourse getCourse(String name)//getCourse声明为静态方法，可以通过类名直接调用
    {
        
        //方式2.
        if(name.equals("java"))
        {
            return (ICourse)new JavaCourse();
        
        }else
        {
            return (ICourse)new HtmlCourse();
        }
        
        
        
        /*
        //方式3.
        //获取IOC容器
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        if(name.equals("java"))
        {
            return (ICourse)context.getBean("JavaCourse");     // new -> 从 IOC获取
        }
        else if(name.equals("html"))
        {
            return (ICourse)context.getBean("HtmlCourse");      // new -> 从 IOC获取
        }
        */
    }
}

<?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">

    <!-- 该文件中所产生的所有对象，被spring放入了一个称之为spring IOC 容器的地方 -->
    <!-- id:唯一标识符  class：指定类型 -->
    <bean id = "student" class = "org.ks.entity.Student">  <!-- 相当于：Student stu = new Student() -->
        <!-- property:该class代表的类的属性
            name:属性名
            value:属性值
         -->
        <property name="stuName" value = "李四"></property>
        <property name="stuAge" value = "20"></property>
        <property name="stuNo" value = "13"></property>
    </bean>
    
    <bean id = "JavaCourse" class = "org.ks.newinstance.JavaCourse">
        
    </bean>
    
    <bean id = "HtmlCourse" class = "org.ks.newinstance.HtmlCourse">
        
    </bean>
</beans>

package org.ks.test;

import org.ks.entity.Student;
import org.ks.factory.CourseFactory;
import org.ks.newinstance.ICourse;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class test2 {
    //方式1.
    public static void learnCourse()
    {
        Student stu = new Student();
        stu.learnjava();
        stu.learnhtml();
    }
    
    //方式2.
    public static void learnCourseWithFactory()
    {
        Student stu = new Student();
        stu.learn("html");
    }
    
    //方式3.
    public static void learnCourseWithIOC()
    {
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        //执行从springioc容器中获取一个id为student的对象
        Student stu = (Student)context.getBean("student");  //new Student() 变成  从IOC获取student
        stu.learn("HtmlCourse");
    }
    
    public static void main(String[] args) 
    {
        //learnCourse();           //方式1.直接通过创建Student对象的方式
        //learnCourseWithFactory();         //方式2.自己设置建档工厂的方式
        learnCourseWithIOC();          //方式3.通过SpringIOC(超级工厂)的方式
    } 
}