spring - spring框架基本原理

原文链接：https://blog.csdn.net/kingyxfly/article/details/79826333

1.spring: 创建Bean和维护Bean之间的关系
IOC（控制反转/依赖注入）、AOP（面向切面编程）

2.AOP:
这种在运行时，动态的将代码切入到类的指定方法、指定位置的编程思想。

3.反射：在spring-config.xml中的id->class，找到文件类

4.

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以下为链接内容：

小汽车类Car

package com.example;

public class Car {
    private String name;
    private double price;

    // 省略getter，setter

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

    public void carInfo() {
        System.out.println("i have this car: " + name);
    }
}

汽车拥有者类:Person

package com.example;

public class Person {
    private String name;
    private int age;
    private Car car;

     // 省略getter，setter

    @Override
    public String toString() {
        return "Person{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", car=" + car +
                '}';
    }
}

Spring配置文件spring-config.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="car" class="com.example.Car">
        <property name="name" value="hongqi"/>
        <property name="price" value="1000000.0"/>
    </bean>

    <bean id="person" class="com.example.Person">
        <property name="name" value="zhaangsan"/>
        <property name="age" value="27"/>
        <property name="car" ref="car"/>
    </bean>
</beans>

测试类SpringMain

package com.example;

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

public class SpringMain {
    public static void main(String[] args) {
        // 创建IOC容器
        ApplicationContext context = new ClassPathXmlApplicationContext("spring-config.xml");
        // 通过getBean获取Car的实例，这里利用了反射
        Car car = (Car) context.getBean("car");
        car.carInfo();

        System.out.println(car.toString());
        Person person = (Person) context.getBean("person");
        System.out.println(person.toString());
    }
}

执行结果：

i have this car: hongqi
Car{name='hongqi', price=1000000.0}
Person{name='zhaangsan', age=27, car=Car{name='hongqi', price=1000000.0}}