day03-02 Spring IoC学习

作者: 黑桃_06ea | 来源:发表于2019-03-05 10:51 被阅读0次

1、了解IoC

IoC（Inversion of Control，控制反转）容器是Spring框架中非常重要的核心组件，可以说它是伴随Spring的诞生和成长的组件。Spring通过IoC容器来管理所有的Java对象（也称bean）及其相互间的依赖关系。

2、依赖注入和控制反转

依赖注入(Dependency Injection)是对“控制反转”的不同说法，本质是一回事。

3、IoC容器和bean

Spring通过IoC容器来管理所有Java对象及其相互之间的依赖关系。
IoC容器在创建bean的时候，会注入其依赖项。
IoC的应用有以下两种设计模式：

反射：在运行状态中，根据提供的类的路径或类名，通过反射来动态获取该类的所有属性和方法。
工厂模式：把IoC容器当做一个工厂，在配置文件或注解中给出定义，然后利用反射技术，根据给出的类名生成相应的对象。对象生成的代码及对象之间的依赖关系在配置文件中定义，实现了解耦。
Spring IoC容器的核心基础包：
org.springframework.beans
org.springframework.context

4、配置和使用

配置方式有:

xml形式

<bean id = "..." class="...">
   <!-- 放置这个bean的协作者和配置 -->
</bean>

注解形式

@Configuration
public class AppConfig{
    @Bean
    public MyService myService(){
          return new MyServiceImpl();
   }
}

5、注入方式

构造器注入
setter注入

6、依赖注入练习

接口和实现类

public interface MessageService {
    String getMessage();
}

public class MessageServiceImpl implements MessageService {
    private String username;
    private int age;

    public MessageServiceImpl(String username, int age) {
        this.username = username;
        this.age = age;
    }
    @Override
    public String getMessage() {
        return "Hello World!"+username+",age is"+age ;
    }
}

print类

public class MessagePrinter {
    final private MessageService service;
    public MessagePrinter(MessageService service){
        this.service=service;
    }
    public void printMessage(){
        System.out.println(this.service.getMessage());
    }
}

配置bean

<!--定义bean-->
    <bean id="messageServiceImpl" class="com.spring.IoC.MessageServiceImpl">
        <constructor-arg name="username" value="WangJie"/>
        <constructor-arg name="age" value="21"/>
    </bean>
    <bean id="messagePrinter" class="com.spring.IoC.MessagePrinter">
        <constructor-arg name="service" ref="messageServiceImpl"/>
    </bean>

主类

public class MessageApp {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("/beans.xml");
        MessagePrinter messagePrinter = context.getBean(MessagePrinter.class);
        messagePrinter.printMessage();
    }
}

运行结果

7、综合练习

*Car类

public class Car {
    private String brand;
    private String color;
    private String parameter;

    public Car(String brand, String color, String parameter) {
        this.brand = brand;
        this.color = color;
        this.parameter = parameter;
    }

    public String getBrand() {
        return brand;
    }

    public void setBrand(String brand) {
        this.brand = brand;
    }

    public String getColor() {
        return color;
    }

    public void setColor(String color) {
        this.color = color;
    }

    public String getParameter() {
        return parameter;
    }

    public void setParameter(String parameter) {
        this.parameter = parameter;
    }

    @Override
    public String toString() {
        return "Car{" +
                "brand='" + brand + '\'' +
                ", color='" + color + '\'' +
                ", parameter='" + parameter + '\'' +
                '}';
    }
}

Boss类

public class Boss {
    private String name;
    private String company;
    private Car car;
    private List<String> hobby;

    public Boss(String name, String company, Car car, List<String> hobby) {
        this.name = name;
        this.company = company;
        this.car = car;
        this.hobby = hobby;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getCompany() {
        return company;
    }

    public void setCompany(String company) {
        this.company = company;
    }

    public Car getCar() {
        return car;
    }

    public void setCar(Car car) {
        this.car = car;
    }

    public List<String> getHobby() {
        return hobby;
    }

    public void setHobby(List<String> hobby) {
        this.hobby = hobby;
    }

    @Override
    public String toString() {
        return "Boss{" +
                "name='" + name + '\'' +
                ", company='" + company + '\'' +
                ", car=" + car +
                ", hobby=" + hobby +
                '}';
    }
}

Meeting类

import java.util.List;

/**
 * Created by Administrator on 2019/3/4.
 */
public class Meeting {
    private String theme;
    private List<Boss> bosses;

    public Meeting(String theme, List<Boss> bosses) {
        this.theme = theme;
        this.bosses = bosses;
    }

    public String getTheme() {
        return theme;
    }

    public void setTheme(String theme) {
        this.theme = theme;
    }

    public List<Boss> getBosses() {
        return bosses;
    }

    public void setBosses(List<Boss> bosses) {
        this.bosses = bosses;
    }

    @Override
    public String toString() {
        return "Meeting{" +
                "theme='" + theme + '\'' +
                ", bosses=" + bosses +
                '}';
    }
}

配置bean

<bean id="car1" class="com.spring.IoC.Car">
        <constructor-arg name="brand" value="奔驰"/>
        <constructor-arg name="color" value="白色"/>
        <constructor-arg name="parameter" value="6.8T"/>
    </bean>
    <bean id="car2" class="com.spring.IoC.Car">
        <constructor-arg name="brand" value="宝马"/>
        <constructor-arg name="color" value="黑色"/>
        <constructor-arg name="parameter" value="5.0T"/>
    </bean>
    <bean id="car3" class="com.spring.IoC.Car">
        <constructor-arg name="brand" value="劳斯莱斯"/>
        <constructor-arg name="color" value="蓝色"/>
        <constructor-arg name="parameter" value="6.8T"/>
    </bean>
    <bean id="boss1" class="com.spring.IoC.Boss">
        <constructor-arg name="name" value="马化腾"/>
        <constructor-arg name="company" value="腾讯"/>
        <constructor-arg name="car" ref="car1"/>
        <constructor-arg name="hobby">
            <list>
                <value>游戏</value>
                <value>高尔夫</value>
            </list>
        </constructor-arg>
    </bean>
    <bean id="boss2" class="com.spring.IoC.Boss">
        <constructor-arg name="name" value="马云"/>
        <constructor-arg name="company" value="阿里巴巴"/>
        <constructor-arg name="car" ref="car2"/>
        <constructor-arg name="hobby">
            <list>
                <value>唱歌</value>
                <value>演讲</value>
            </list>
        </constructor-arg>
    </bean>
    <bean id="boss3" class="com.spring.IoC.Boss">
        <constructor-arg name="name" value="雷军"/>
        <constructor-arg name="company" value="小米"/>
        <constructor-arg name="car" ref="car3"/>
        <constructor-arg name="hobby">
            <list>
                <value>写作</value>
                <value>阅读</value>
            </list>
        </constructor-arg>
    </bean>
    <bean id="meeting" class="com.spring.IoC.Meeting">
        <constructor-arg name="theme" value="2019互联网分会"/>
        <constructor-arg name="bosses">
            <list>
                <ref bean="boss1"/>
                <ref bean="boss2"/>
                <ref bean="boss3"/>
            </list>
        </constructor-arg>
   </bean>

MeetingApp类

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

/**
 * Created by Administrator on 2019/3/4.
 */
public class MeetingApp{
    public static void main(String[] args) {
        ApplicationContext context=new ClassPathXmlApplicationContext("beans.xml");
        Meeting meeting=context.getBean(Meeting.class);
        System.out.println(meeting);
    }
}

运行结果

day03-12.png

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